Merge pull request #2426 from WenmuZhou/android_demo

add Android demo

.gitignore

@@ -25,3 +25,7 @@ output/
 build/
 dist/
 paddleocr.egg-info/
+/deploy/android_demo/app/OpenCV/
+/deploy/android_demo/app/PaddleLite/
+/deploy/android_demo/app/.cxx/
+/deploy/android_demo/app/cache/

deploy/android_demo/.gitignore

+*.iml
+.gradle
+/local.properties
+/.idea/*
+.DS_Store
+/build
+/captures
+.externalNativeBuild
+

deploy/android_demo/README.md

+# 如何快速测试
+### 1. 安装最新版本的Android Studio
+可以从 https://developer.android.com/studio 下载。本Demo使用是4.0版本Android Studio编写。
+
+### 2. 按照NDK 20 以上版本
+Demo测试的时候使用的是NDK 20b版本，20版本以上均可以支持编译成功。
+
+如果您是初学者，可以用以下方式安装和测试NDK编译环境。
+点击 File -> New ->New Project，  新建  "Native C++" project
+
+### 3. 导入项目
+点击 File->New->Import Project...， 然后跟着Android Studio的引导导入
+
+
+# 获得更多支持
+前往[端计算模型生成平台EasyEdge](https://ai.baidu.com/easyedge/app/open_source_demo?referrerUrl=paddlelite)，获得更多开发支持：
+
+- Demo APP：可使用手机扫码安装，方便手机端快速体验文字识别
+- SDK：模型被封装为适配不同芯片硬件和操作系统SDK，包括完善的接口，方便进行二次开发

deploy/android_demo/app/.gitignore

+/build

deploy/android_demo/app/build.gradle

+import java.security.MessageDigest
+
+apply plugin: 'com.android.application'
+
+android {
+    compileSdkVersion 29
+    defaultConfig {
+        applicationId "com.baidu.paddle.lite.demo.ocr"
+        minSdkVersion 23
+        targetSdkVersion 29
+        versionCode 1
+        versionName "1.0"
+        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
+        externalNativeBuild {
+            cmake {
+                cppFlags "-std=c++11 -frtti -fexceptions -Wno-format"
+                arguments '-DANDROID_PLATFORM=android-23', '-DANDROID_STL=c++_shared' ,"-DANDROID_ARM_NEON=TRUE"
+            }
+        }
+        ndk {
+            // abiFilters "arm64-v8a", "armeabi-v7a"
+            abiFilters   "arm64-v8a", "armeabi-v7a"
+            ldLibs "jnigraphics"
+        }
+    }
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+        }
+    }
+    externalNativeBuild {
+        cmake {
+            path "src/main/cpp/CMakeLists.txt"
+            version "3.10.2"
+        }
+    }
+}
+
+dependencies {
+    implementation fileTree(include: ['*.jar'], dir: 'libs')
+    implementation 'androidx.appcompat:appcompat:1.1.0'
+    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
+    testImplementation 'junit:junit:4.12'
+    androidTestImplementation 'com.android.support.test:runner:1.0.2'
+    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
+}
+
+def archives = [
+        [
+                'src' : 'https://paddleocr.bj.bcebos.com/dygraph_v2.0/lite/paddle_lite_libs_v2_9_0.tar.gz',
+                'dest': 'PaddleLite'
+        ],
+        [
+                'src' : 'https://paddlelite-demo.bj.bcebos.com/libs/android/opencv-4.2.0-android-sdk.tar.gz',
+                'dest': 'OpenCV'
+        ],
+        [
+                'src' : 'https://paddleocr.bj.bcebos.com/dygraph_v2.0/lite/ocr_v2_for_cpu.tar.gz',
+                'dest' : 'src/main/assets/models'
+        ],
+        [
+                'src' : 'https://paddleocr.bj.bcebos.com/dygraph_v2.0/lite/ch_dict.tar.gz',
+                'dest' : 'src/main/assets/labels'
+        ]
+]
+
+task downloadAndExtractArchives(type: DefaultTask) {
+    doFirst {
+        println "Downloading and extracting archives including libs and models"
+    }
+    doLast {
+        // Prepare cache folder for archives
+        String cachePath = "cache"
+        if (!file("${cachePath}").exists()) {
+            mkdir "${cachePath}"
+        }
+        archives.eachWithIndex { archive, index ->
+            MessageDigest messageDigest = MessageDigest.getInstance('MD5')
+            messageDigest.update(archive.src.bytes)
+            String cacheName = new BigInteger(1, messageDigest.digest()).toString(32)
+            // Download the target archive if not exists
+            boolean copyFiles = !file("${archive.dest}").exists()
+            if (!file("${cachePath}/${cacheName}.tar.gz").exists()) {
+                ant.get(src: archive.src, dest: file("${cachePath}/${cacheName}.tar.gz"))
+                copyFiles = true; // force to copy files from the latest archive files
+            }
+            // Extract the target archive if its dest path does not exists
+            if (copyFiles) {
+                copy {
+                    from tarTree("${cachePath}/${cacheName}.tar.gz")
+                    into "${archive.dest}"
+                }
+            }
+        }
+    }
+}
+preBuild.dependsOn downloadAndExtractArchives
\ No newline at end of file

deploy/android_demo/app/proguard-rules.pro

+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

deploy/android_demo/app/src/androidTest/java/com/baidu/paddle/lite/demo/ocr/ExampleInstrumentedTest.java

+package com.baidu.paddle.lite.demo.ocr;
+
+import android.content.Context;
+import android.support.test.InstrumentationRegistry;
+import android.support.test.runner.AndroidJUnit4;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import static org.junit.Assert.*;
+
+/**
+ * Instrumented test, which will execute on an Android device.
+ *
+ * @see <a href="http://d.android.com/tools/testing">Testing documentation</a>
+ */
+@RunWith(AndroidJUnit4.class)
+public class ExampleInstrumentedTest {
+    @Test
+    public void useAppContext() {
+        // Context of the app under test.
+        Context appContext = InstrumentationRegistry.getTargetContext();
+
+        assertEquals("com.baidu.paddle.lite.demo", appContext.getPackageName());
+    }
+}

deploy/android_demo/app/src/main/AndroidManifest.xml

+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+          package="com.baidu.paddle.lite.demo.ocr">
+
+    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
+    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
+    <uses-permission android:name="android.permission.CAMERA"/>
+
+
+    <application
+            android:allowBackup="true"
+            android:icon="@mipmap/ic_launcher"
+            android:label="@string/app_name"
+            android:roundIcon="@mipmap/ic_launcher_round"
+            android:supportsRtl="true"
+            android:theme="@style/AppTheme">
+        <!-- to test MiniActivity, change this to com.baidu.paddle.lite.demo.ocr.MiniActivity -->
+        <activity android:name="com.baidu.paddle.lite.demo.ocr.MainActivity">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN"/>
+                <category android:name="android.intent.category.LAUNCHER"/>
+            </intent-filter>
+        </activity>
+        <activity
+                android:name="com.baidu.paddle.lite.demo.ocr.SettingsActivity"
+                android:label="Settings">
+        </activity>
+        <provider
+            android:name="androidx.core.content.FileProvider"
+            android:authorities="com.baidu.paddle.lite.demo.ocr.fileprovider"
+            android:exported="false"
+            android:grantUriPermissions="true">
+            <meta-data
+                android:name="android.support.FILE_PROVIDER_PATHS"
+                android:resource="@xml/file_paths"></meta-data>
+        </provider>
+    </application>
+
+</manifest>
\ No newline at end of file

deploy/android_demo/app/src/main/cpp/CMakeLists.txt

+# For more information about using CMake with Android Studio, read the
+# documentation: https://d.android.com/studio/projects/add-native-code.html
+
+# Sets the minimum version of CMake required to build the native library.
+
+cmake_minimum_required(VERSION 3.4.1)
+
+# Creates and names a library, sets it as either STATIC or SHARED, and provides
+# the relative paths to its source code. You can define multiple libraries, and
+# CMake builds them for you. Gradle automatically packages shared libraries with
+# your APK.
+
+set(PaddleLite_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../../../PaddleLite")
+include_directories(${PaddleLite_DIR}/cxx/include)
+
+set(OpenCV_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../../../OpenCV/sdk/native/jni")
+message(STATUS "opencv dir: ${OpenCV_DIR}")
+find_package(OpenCV REQUIRED)
+message(STATUS "OpenCV libraries: ${OpenCV_LIBS}")
+include_directories(${OpenCV_INCLUDE_DIRS})
+aux_source_directory(. SOURCES)
+set(CMAKE_CXX_FLAGS
+        "${CMAKE_CXX_FLAGS} -ffast-math -Ofast -Os"
+        )
+set(CMAKE_CXX_FLAGS
+        "${CMAKE_CXX_FLAGS} -fvisibility=hidden -fvisibility-inlines-hidden -fdata-sections -ffunction-sections"
+        )
+set(CMAKE_SHARED_LINKER_FLAGS
+        "${CMAKE_SHARED_LINKER_FLAGS} -Wl,--gc-sections -Wl,-z,nocopyreloc")
+
+add_library(
+        # Sets the name of the library.
+        Native
+        # Sets the library as a shared library.
+        SHARED
+        # Provides a relative path to your source file(s).
+        ${SOURCES})
+
+find_library(
+        # Sets the name of the path variable.
+        log-lib
+        # Specifies the name of the NDK library that you want CMake to locate.
+        log)
+
+add_library(
+        # Sets the name of the library.
+        paddle_light_api_shared
+        # Sets the library as a shared library.
+        SHARED
+        # Provides a relative path to your source file(s).
+        IMPORTED)
+
+set_target_properties(
+        # Specifies the target library.
+        paddle_light_api_shared
+        # Specifies the parameter you want to define.
+        PROPERTIES
+        IMPORTED_LOCATION
+        ${PaddleLite_DIR}/cxx/libs/${ANDROID_ABI}/libpaddle_light_api_shared.so
+        # Provides the path to the library you want to import.
+)
+
+
+# Specifies libraries CMake should link to your target library. You can link
+# multiple libraries, such as libraries you define in this build script,
+# prebuilt third-party libraries, or system libraries.
+
+target_link_libraries(
+        # Specifies the target library.
+        Native
+        paddle_light_api_shared
+        ${OpenCV_LIBS}
+        GLESv2
+        EGL
+        jnigraphics
+        ${log-lib}
+)
+
+add_custom_command(
+        TARGET Native
+        POST_BUILD
+        COMMAND
+        ${CMAKE_COMMAND} -E copy
+        ${PaddleLite_DIR}/cxx/libs/${ANDROID_ABI}/libc++_shared.so
+        ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/libc++_shared.so)
+
+add_custom_command(
+        TARGET Native
+        POST_BUILD
+        COMMAND
+        ${CMAKE_COMMAND} -E copy
+        ${PaddleLite_DIR}/cxx/libs/${ANDROID_ABI}/libpaddle_light_api_shared.so
+        ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/libpaddle_light_api_shared.so)
+
+add_custom_command(
+        TARGET Native
+        POST_BUILD
+        COMMAND
+        ${CMAKE_COMMAND} -E copy
+        ${PaddleLite_DIR}/cxx/libs/${ANDROID_ABI}/libhiai.so
+        ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/libhiai.so)
+
+add_custom_command(
+        TARGET Native
+        POST_BUILD
+        COMMAND
+        ${CMAKE_COMMAND} -E copy
+        ${PaddleLite_DIR}/cxx/libs/${ANDROID_ABI}/libhiai_ir.so
+        ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/libhiai_ir.so)
+
+add_custom_command(
+        TARGET Native
+        POST_BUILD
+        COMMAND
+        ${CMAKE_COMMAND} -E copy
+        ${PaddleLite_DIR}/cxx/libs/${ANDROID_ABI}/libhiai_ir_build.so
+        ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/libhiai_ir_build.so)
\ No newline at end of file

deploy/android_demo/app/src/main/cpp/common.h

+//
+// Created by fu on 4/25/18.
+//
+
+#pragma once
+#import <numeric>
+#import <vector>
+
+#ifdef __ANDROID__
+
+#include <android/log.h>
+
+#define LOG_TAG "OCR_NDK"
+
+#define LOGI(...) __android_log_print(ANDROID_LOG_INFO, LOG_TAG, __VA_ARGS__)
+#define LOGW(...) __android_log_print(ANDROID_LOG_WARN, LOG_TAG, __VA_ARGS__)
+#define LOGE(...) __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, __VA_ARGS__)
+#else
+#include <stdio.h>
+#define LOGI(format, ...)                                                      \
+  fprintf(stdout, "[" LOG_TAG "]" format "\n", ##__VA_ARGS__)
+#define LOGW(format, ...)                                                      \
+  fprintf(stdout, "[" LOG_TAG "]" format "\n", ##__VA_ARGS__)
+#define LOGE(format, ...)                                                      \
+  fprintf(stderr, "[" LOG_TAG "]Error: " format "\n", ##__VA_ARGS__)
+#endif
+
+enum RETURN_CODE { RETURN_OK = 0 };
+
+enum NET_TYPE { NET_OCR = 900100, NET_OCR_INTERNAL = 991008 };
+
+template <typename T> inline T product(const std::vector<T> &vec) {
+  if (vec.empty()) {
+    return 0;
+  }
+  return std::accumulate(vec.begin(), vec.end(), 1, std::multiplies<T>());
+}

deploy/android_demo/app/src/main/cpp/native.cpp

+//
+// Created by fujiayi on 2020/7/5.
+//
+
+#include "native.h"
+#include "ocr_ppredictor.h"
+#include <algorithm>
+#include <paddle_api.h>
+#include <string>
+
+static paddle::lite_api::PowerMode str_to_cpu_mode(const std::string &cpu_mode);
+
+extern "C" JNIEXPORT jlong JNICALL
+Java_com_baidu_paddle_lite_demo_ocr_OCRPredictorNative_init(
+    JNIEnv *env, jobject thiz, jstring j_det_model_path,
+    jstring j_rec_model_path, jstring j_cls_model_path, jint j_thread_num,
+    jstring j_cpu_mode) {
+  std::string det_model_path = jstring_to_cpp_string(env, j_det_model_path);
+  std::string rec_model_path = jstring_to_cpp_string(env, j_rec_model_path);
+  std::string cls_model_path = jstring_to_cpp_string(env, j_cls_model_path);
+  int thread_num = j_thread_num;
+  std::string cpu_mode = jstring_to_cpp_string(env, j_cpu_mode);
+  ppredictor::OCR_Config conf;
+  conf.thread_num = thread_num;
+  conf.mode = str_to_cpu_mode(cpu_mode);
+  ppredictor::OCR_PPredictor *orc_predictor =
+      new ppredictor::OCR_PPredictor{conf};
+  orc_predictor->init_from_file(det_model_path, rec_model_path, cls_model_path);
+  return reinterpret_cast<jlong>(orc_predictor);
+}
+
+/**
+ * "LITE_POWER_HIGH" convert to paddle::lite_api::LITE_POWER_HIGH
+ * @param cpu_mode
+ * @return
+ */
+static paddle::lite_api::PowerMode
+str_to_cpu_mode(const std::string &cpu_mode) {
+  static std::map<std::string, paddle::lite_api::PowerMode> cpu_mode_map{
+      {"LITE_POWER_HIGH", paddle::lite_api::LITE_POWER_HIGH},
+      {"LITE_POWER_LOW", paddle::lite_api::LITE_POWER_HIGH},
+      {"LITE_POWER_FULL", paddle::lite_api::LITE_POWER_FULL},
+      {"LITE_POWER_NO_BIND", paddle::lite_api::LITE_POWER_NO_BIND},
+      {"LITE_POWER_RAND_HIGH", paddle::lite_api::LITE_POWER_RAND_HIGH},
+      {"LITE_POWER_RAND_LOW", paddle::lite_api::LITE_POWER_RAND_LOW}};
+  std::string upper_key;
+  std::transform(cpu_mode.cbegin(), cpu_mode.cend(), upper_key.begin(),
+                 ::toupper);
+  auto index = cpu_mode_map.find(upper_key);
+  if (index == cpu_mode_map.end()) {
+    LOGE("cpu_mode not found %s", upper_key.c_str());
+    return paddle::lite_api::LITE_POWER_HIGH;
+  } else {
+    return index->second;
+  }
+}
+
+extern "C" JNIEXPORT jfloatArray JNICALL
+Java_com_baidu_paddle_lite_demo_ocr_OCRPredictorNative_forward(
+    JNIEnv *env, jobject thiz, jlong java_pointer, jfloatArray buf,
+    jfloatArray ddims, jobject original_image) {
+  LOGI("begin to run native forward");
+  if (java_pointer == 0) {
+    LOGE("JAVA pointer is NULL");
+    return cpp_array_to_jfloatarray(env, nullptr, 0);
+  }
+  cv::Mat origin = bitmap_to_cv_mat(env, original_image);
+  if (origin.size == 0) {
+    LOGE("origin bitmap cannot convert to CV Mat");
+    return cpp_array_to_jfloatarray(env, nullptr, 0);
+  }
+  ppredictor::OCR_PPredictor *ppredictor =
+      (ppredictor::OCR_PPredictor *)java_pointer;
+  std::vector<float> dims_float_arr = jfloatarray_to_float_vector(env, ddims);
+  std::vector<int64_t> dims_arr;
+  dims_arr.resize(dims_float_arr.size());
+  std::copy(dims_float_arr.cbegin(), dims_float_arr.cend(), dims_arr.begin());
+
+  // 这里值有点大，就不调用jfloatarray_to_float_vector了
+  int64_t buf_len = (int64_t)env->GetArrayLength(buf);
+  jfloat *buf_data = env->GetFloatArrayElements(buf, JNI_FALSE);
+  float *data = (jfloat *)buf_data;
+  std::vector<ppredictor::OCRPredictResult> results =
+      ppredictor->infer_ocr(dims_arr, data, buf_len, NET_OCR, origin);
+  LOGI("infer_ocr finished with boxes %ld", results.size());
+  // 这里将std::vector<ppredictor::OCRPredictResult> 序列化成
+  // float数组，传输到java层再反序列化
+  std::vector<float> float_arr;
+  for (const ppredictor::OCRPredictResult &r : results) {
+    float_arr.push_back(r.points.size());
+    float_arr.push_back(r.word_index.size());
+    float_arr.push_back(r.score);
+    for (const std::vector<int> &point : r.points) {
+      float_arr.push_back(point.at(0));
+      float_arr.push_back(point.at(1));
+    }
+    for (int index : r.word_index) {
+      float_arr.push_back(index);
+    }
+  }
+  return cpp_array_to_jfloatarray(env, float_arr.data(), float_arr.size());
+}
+
+extern "C" JNIEXPORT void JNICALL
+Java_com_baidu_paddle_lite_demo_ocr_OCRPredictorNative_release(
+    JNIEnv *env, jobject thiz, jlong java_pointer) {
+  if (java_pointer == 0) {
+    LOGE("JAVA pointer is NULL");
+    return;
+  }
+  ppredictor::OCR_PPredictor *ppredictor =
+      (ppredictor::OCR_PPredictor *)java_pointer;
+  delete ppredictor;
+}
\ No newline at end of file

deploy/android_demo/app/src/main/cpp/native.h

+//
+// Created by fujiayi on 2020/7/5.
+//
+
+#pragma once
+
+#include "common.h"
+#include <android/bitmap.h>
+#include <jni.h>
+#include <opencv2/opencv.hpp>
+#include <string>
+#include <vector>
+
+inline std::string jstring_to_cpp_string(JNIEnv *env, jstring jstr) {
+  // In java, a unicode char will be encoded using 2 bytes (utf16).
+  // so jstring will contain characters utf16. std::string in c++ is
+  // essentially a string of bytes, not characters, so if we want to
+  // pass jstring from JNI to c++, we have convert utf16 to bytes.
+  if (!jstr) {
+    return "";
+  }
+  const jclass stringClass = env->GetObjectClass(jstr);
+  const jmethodID getBytes =
+      env->GetMethodID(stringClass, "getBytes", "(Ljava/lang/String;)[B");
+  const jbyteArray stringJbytes = (jbyteArray)env->CallObjectMethod(
+      jstr, getBytes, env->NewStringUTF("UTF-8"));
+
+  size_t length = (size_t)env->GetArrayLength(stringJbytes);
+  jbyte *pBytes = env->GetByteArrayElements(stringJbytes, NULL);
+
+  std::string ret = std::string(reinterpret_cast<char *>(pBytes), length);
+  env->ReleaseByteArrayElements(stringJbytes, pBytes, JNI_ABORT);
+
+  env->DeleteLocalRef(stringJbytes);
+  env->DeleteLocalRef(stringClass);
+  return ret;
+}
+
+inline jstring cpp_string_to_jstring(JNIEnv *env, std::string str) {
+  auto *data = str.c_str();
+  jclass strClass = env->FindClass("java/lang/String");
+  jmethodID strClassInitMethodID =
+      env->GetMethodID(strClass, "<init>", "([BLjava/lang/String;)V");
+
+  jbyteArray bytes = env->NewByteArray(strlen(data));
+  env->SetByteArrayRegion(bytes, 0, strlen(data),
+                          reinterpret_cast<const jbyte *>(data));
+
+  jstring encoding = env->NewStringUTF("UTF-8");
+  jstring res = (jstring)(
+      env->NewObject(strClass, strClassInitMethodID, bytes, encoding));
+
+  env->DeleteLocalRef(strClass);
+  env->DeleteLocalRef(encoding);
+  env->DeleteLocalRef(bytes);
+
+  return res;
+}
+
+inline jfloatArray cpp_array_to_jfloatarray(JNIEnv *env, const float *buf,
+                                            int64_t len) {
+  if (len == 0) {
+    return env->NewFloatArray(0);
+  }
+  jfloatArray result = env->NewFloatArray(len);
+  env->SetFloatArrayRegion(result, 0, len, buf);
+  return result;
+}
+
+inline jintArray cpp_array_to_jintarray(JNIEnv *env, const int *buf,
+                                        int64_t len) {
+  jintArray result = env->NewIntArray(len);
+  env->SetIntArrayRegion(result, 0, len, buf);
+  return result;
+}
+
+inline jbyteArray cpp_array_to_jbytearray(JNIEnv *env, const int8_t *buf,
+                                          int64_t len) {
+  jbyteArray result = env->NewByteArray(len);
+  env->SetByteArrayRegion(result, 0, len, buf);
+  return result;
+}
+
+inline jlongArray int64_vector_to_jlongarray(JNIEnv *env,
+                                             const std::vector<int64_t> &vec) {
+  jlongArray result = env->NewLongArray(vec.size());
+  jlong *buf = new jlong[vec.size()];
+  for (size_t i = 0; i < vec.size(); ++i) {
+    buf[i] = (jlong)vec[i];
+  }
+  env->SetLongArrayRegion(result, 0, vec.size(), buf);
+  delete[] buf;
+  return result;
+}
+
+inline std::vector<int64_t> jlongarray_to_int64_vector(JNIEnv *env,
+                                                       jlongArray data) {
+  int data_size = env->GetArrayLength(data);
+  jlong *data_ptr = env->GetLongArrayElements(data, nullptr);
+  std::vector<int64_t> data_vec(data_ptr, data_ptr + data_size);
+  env->ReleaseLongArrayElements(data, data_ptr, 0);
+  return data_vec;
+}
+
+inline std::vector<float> jfloatarray_to_float_vector(JNIEnv *env,
+                                                      jfloatArray data) {
+  int data_size = env->GetArrayLength(data);
+  jfloat *data_ptr = env->GetFloatArrayElements(data, nullptr);
+  std::vector<float> data_vec(data_ptr, data_ptr + data_size);
+  env->ReleaseFloatArrayElements(data, data_ptr, 0);
+  return data_vec;
+}
+
+inline cv::Mat bitmap_to_cv_mat(JNIEnv *env, jobject bitmap) {
+  AndroidBitmapInfo info;
+  int result = AndroidBitmap_getInfo(env, bitmap, &info);
+  if (result != ANDROID_BITMAP_RESULT_SUCCESS) {
+    LOGE("AndroidBitmap_getInfo failed, result: %d", result);
+    return cv::Mat{};
+  }
+  if (info.format != ANDROID_BITMAP_FORMAT_RGBA_8888) {
+    LOGE("Bitmap format is not RGBA_8888 !");
+    return cv::Mat{};
+  }
+  unsigned char *srcData = NULL;
+  AndroidBitmap_lockPixels(env, bitmap, (void **)&srcData);
+  cv::Mat mat = cv::Mat::zeros(info.height, info.width, CV_8UC4);
+  memcpy(mat.data, srcData, info.height * info.width * 4);
+  AndroidBitmap_unlockPixels(env, bitmap);
+  cv::cvtColor(mat, mat, cv::COLOR_RGBA2BGR);
+  /**
+  if (!cv::imwrite("/sdcard/1/copy.jpg", mat)){
+      LOGE("Write image failed " );
+  }
+   */
+  return mat;
+}

deploy/android_demo/app/src/main/cpp/ocr_clipper.cpp

+/*******************************************************************************
+*                                                                              *
+* Author    :  Angus Johnson                                                   *
+* Version   :  6.4.2                                                           *
+* Date      :  27 February 2017                                                *
+* Website   :  http://www.angusj.com                                           *
+* Copyright :  Angus Johnson 2010-2017                                         *
+*                                                                              *
+* License:                                                                     *
+* Use, modification & distribution is subject to Boost Software License Ver 1. *
+* http://www.boost.org/LICENSE_1_0.txt                                         *
+*                                                                              *
+* Attributions:                                                                *
+* The code in this library is an extension of Bala Vatti's clipping algorithm: *
+* "A generic solution to polygon clipping"                                     *
+* Communications of the ACM, Vol 35, Issue 7 (July 1992) pp 56-63.             *
+* http://portal.acm.org/citation.cfm?id=129906                                 *
+*                                                                              *
+* Computer graphics and geometric modeling: implementation and algorithms      *
+* By Max K. Agoston                                                            *
+* Springer; 1 edition (January 4, 2005)                                        *
+* http://books.google.com/books?q=vatti+clipping+agoston                       *
+*                                                                              *
+* See also:                                                                    *
+* "Polygon Offsetting by Computing Winding Numbers"                            *
+* Paper no. DETC2005-85513 pp. 565-575                                         *
+* ASME 2005 International Design Engineering Technical Conferences             *
+* and Computers and Information in Engineering Conference (IDETC/CIE2005)      *
+* September 24-28, 2005 , Long Beach, California, USA                          *
+* http://www.me.berkeley.edu/~mcmains/pubs/DAC05OffsetPolygon.pdf              *
+*                                                                              *
+*******************************************************************************/
+
+/*******************************************************************************
+*                                                                              *
+* This is a translation of the Delphi Clipper library and the naming style     *
+* used has retained a Delphi flavour.                                          *
+*                                                                              *
+*******************************************************************************/
+
+#include "ocr_clipper.hpp"
+#include <algorithm>
+#include <cmath>
+#include <cstdlib>
+#include <cstring>
+#include <functional>
+#include <ostream>
+#include <stdexcept>
+#include <vector>
+
+namespace ClipperLib {
+
+static double const pi = 3.141592653589793238;
+static double const two_pi = pi * 2;
+static double const def_arc_tolerance = 0.25;
+
+enum Direction { dRightToLeft, dLeftToRight };
+
+static int const Unassigned = -1; // edge not currently 'owning' a solution
+static int const Skip = -2;       // edge that would otherwise close a path
+
+#define HORIZONTAL (-1.0E+40)
+#define TOLERANCE (1.0e-20)
+#define NEAR_ZERO(val) (((val) > -TOLERANCE) && ((val) < TOLERANCE))
+
+struct TEdge {
+  IntPoint Bot;
+  IntPoint Curr; // current (updated for every new scanbeam)
+  IntPoint Top;
+  double Dx;
+  PolyType PolyTyp;
+  EdgeSide Side; // side only refers to current side of solution poly
+  int WindDelta; // 1 or -1 depending on winding direction
+  int WindCnt;
+  int WindCnt2; // winding count of the opposite polytype
+  int OutIdx;
+  TEdge *Next;
+  TEdge *Prev;
+  TEdge *NextInLML;
+  TEdge *NextInAEL;
+  TEdge *PrevInAEL;
+  TEdge *NextInSEL;
+  TEdge *PrevInSEL;
+};
+
+struct IntersectNode {
+  TEdge *Edge1;
+  TEdge *Edge2;
+  IntPoint Pt;
+};
+
+struct LocalMinimum {
+  cInt Y;
+  TEdge *LeftBound;
+  TEdge *RightBound;
+};
+
+struct OutPt;
+
+// OutRec: contains a path in the clipping solution. Edges in the AEL will
+// carry a pointer to an OutRec when they are part of the clipping solution.
+struct OutRec {
+  int Idx;
+  bool IsHole;
+  bool IsOpen;
+  OutRec *FirstLeft; // see comments in clipper.pas
+  PolyNode *PolyNd;
+  OutPt *Pts;
+  OutPt *BottomPt;
+};
+
+struct OutPt {
+  int Idx;
+  IntPoint Pt;
+  OutPt *Next;
+  OutPt *Prev;
+};
+
+struct Join {
+  OutPt *OutPt1;
+  OutPt *OutPt2;
+  IntPoint OffPt;
+};
+
+struct LocMinSorter {
+  inline bool operator()(const LocalMinimum &locMin1,
+                         const LocalMinimum &locMin2) {
+    return locMin2.Y < locMin1.Y;
+  }
+};
+
+//------------------------------------------------------------------------------
+//------------------------------------------------------------------------------
+
+inline cInt Round(double val) {
+  if ((val < 0))
+    return static_cast<cInt>(val - 0.5);
+  else
+    return static_cast<cInt>(val + 0.5);
+}
+//------------------------------------------------------------------------------
+
+inline cInt Abs(cInt val) { return val < 0 ? -val : val; }
+
+//------------------------------------------------------------------------------
+// PolyTree methods ...
+//------------------------------------------------------------------------------
+
+void PolyTree::Clear() {
+  for (PolyNodes::size_type i = 0; i < AllNodes.size(); ++i)
+    delete AllNodes[i];
+  AllNodes.resize(0);
+  Childs.resize(0);
+}
+//------------------------------------------------------------------------------
+
+PolyNode *PolyTree::GetFirst() const {
+  if (!Childs.empty())
+    return Childs[0];
+  else
+    return 0;
+}
+//------------------------------------------------------------------------------
+
+int PolyTree::Total() const {
+  int result = (int)AllNodes.size();
+  // with negative offsets, ignore the hidden outer polygon ...
+  if (result > 0 && Childs[0] != AllNodes[0])
+    result--;
+  return result;
+}
+
+//------------------------------------------------------------------------------
+// PolyNode methods ...
+//------------------------------------------------------------------------------
+
+PolyNode::PolyNode() : Parent(0), Index(0), m_IsOpen(false) {}
+//------------------------------------------------------------------------------
+
+int PolyNode::ChildCount() const { return (int)Childs.size(); }
+//------------------------------------------------------------------------------
+
+void PolyNode::AddChild(PolyNode &child) {
+  unsigned cnt = (unsigned)Childs.size();
+  Childs.push_back(&child);
+  child.Parent = this;
+  child.Index = cnt;
+}
+//------------------------------------------------------------------------------
+
+PolyNode *PolyNode::GetNext() const {
+  if (!Childs.empty())
+    return Childs[0];
+  else
+    return GetNextSiblingUp();
+}
+//------------------------------------------------------------------------------
+
+PolyNode *PolyNode::GetNextSiblingUp() const {
+  if (!Parent) // protects against PolyTree.GetNextSiblingUp()
+    return 0;
+  else if (Index == Parent->Childs.size() - 1)
+    return Parent->GetNextSiblingUp();
+  else
+    return Parent->Childs[Index + 1];
+}
+//------------------------------------------------------------------------------
+
+bool PolyNode::IsHole() const {
+  bool result = true;
+  PolyNode *node = Parent;
+  while (node) {
+    result = !result;
+    node = node->Parent;
+  }
+  return result;
+}
+//------------------------------------------------------------------------------
+
+bool PolyNode::IsOpen() const { return m_IsOpen; }
+//------------------------------------------------------------------------------
+
+#ifndef use_int32
+
+//------------------------------------------------------------------------------
+// Int128 class (enables safe math on signed 64bit integers)
+// eg Int128 val1((long64)9223372036854775807); //ie 2^63 -1
+//    Int128 val2((long64)9223372036854775807);
+//    Int128 val3 = val1 * val2;
+//    val3.AsString => "85070591730234615847396907784232501249" (8.5e+37)
+//------------------------------------------------------------------------------
+
+class Int128 {
+public:
+  ulong64 lo;
+  long64 hi;
+
+  Int128(long64 _lo = 0) {
+    lo = (ulong64)_lo;
+    if (_lo < 0)
+      hi = -1;
+    else
+      hi = 0;
+  }
+
+  Int128(const Int128 &val) : lo(val.lo), hi(val.hi) {}
+
+  Int128(const long64 &_hi, const ulong64 &_lo) : lo(_lo), hi(_hi) {}
+
+  Int128 &operator=(const long64 &val) {
+    lo = (ulong64)val;
+    if (val < 0)
+      hi = -1;
+    else
+      hi = 0;
+    return *this;
+  }
+
+  bool operator==(const Int128 &val) const {
+    return (hi == val.hi && lo == val.lo);
+  }
+
+  bool operator!=(const Int128 &val) const { return !(*this == val); }
+
+  bool operator>(const Int128 &val) const {
+    if (hi != val.hi)
+      return hi > val.hi;
+    else
+      return lo > val.lo;
+  }
+
+  bool operator<(const Int128 &val) const {
+    if (hi != val.hi)
+      return hi < val.hi;
+    else
+      return lo < val.lo;
+  }
+
+  bool operator>=(const Int128 &val) const { return !(*this < val); }
+
+  bool operator<=(const Int128 &val) const { return !(*this > val); }
+
+  Int128 &operator+=(const Int128 &rhs) {
+    hi += rhs.hi;
+    lo += rhs.lo;
+    if (lo < rhs.lo)
+      hi++;
+    return *this;
+  }
+
+  Int128 operator+(const Int128 &rhs) const {
+    Int128 result(*this);
+    result += rhs;
+    return result;
+  }
+
+  Int128 &operator-=(const Int128 &rhs) {
+    *this += -rhs;
+    return *this;
+  }
+
+  Int128 operator-(const Int128 &rhs) const {
+    Int128 result(*this);
+    result -= rhs;
+    return result;
+  }
+
+  Int128 operator-() const // unary negation
+  {
+    if (lo == 0)
+      return Int128(-hi, 0);
+    else
+      return Int128(~hi, ~lo + 1);
+  }
+
+  operator double() const {
+    const double shift64 = 18446744073709551616.0; // 2^64
+    if (hi < 0) {
+      if (lo == 0)
+        return (double)hi * shift64;
+      else
+        return -(double)(~lo + ~hi * shift64);
+    } else
+      return (double)(lo + hi * shift64);
+  }
+};
+//------------------------------------------------------------------------------
+
+Int128 Int128Mul(long64 lhs, long64 rhs) {
+  bool negate = (lhs < 0) != (rhs < 0);
+
+  if (lhs < 0)
+    lhs = -lhs;
+  ulong64 int1Hi = ulong64(lhs) >> 32;
+  ulong64 int1Lo = ulong64(lhs & 0xFFFFFFFF);
+
+  if (rhs < 0)
+    rhs = -rhs;
+  ulong64 int2Hi = ulong64(rhs) >> 32;
+  ulong64 int2Lo = ulong64(rhs & 0xFFFFFFFF);
+
+  // nb: see comments in clipper.pas
+  ulong64 a = int1Hi * int2Hi;
+  ulong64 b = int1Lo * int2Lo;
+  ulong64 c = int1Hi * int2Lo + int1Lo * int2Hi;
+
+  Int128 tmp;
+  tmp.hi = long64(a + (c >> 32));
+  tmp.lo = long64(c << 32);
+  tmp.lo += long64(b);
+  if (tmp.lo < b)
+    tmp.hi++;
+  if (negate)
+    tmp = -tmp;
+  return tmp;
+};
+#endif
+
+//------------------------------------------------------------------------------
+// Miscellaneous global functions
+//------------------------------------------------------------------------------
+
+bool Orientation(const Path &poly) { return Area(poly) >= 0; }
+//------------------------------------------------------------------------------
+
+double Area(const Path &poly) {
+  int size = (int)poly.size();
+  if (size < 3)
+    return 0;
+
+  double a = 0;
+  for (int i = 0, j = size - 1; i < size; ++i) {
+    a += ((double)poly[j].X + poly[i].X) * ((double)poly[j].Y - poly[i].Y);
+    j = i;
+  }
+  return -a * 0.5;
+}
+//------------------------------------------------------------------------------
+
+double Area(const OutPt *op) {
+  const OutPt *startOp = op;
+  if (!op)
+    return 0;
+  double a = 0;
+  do {
+    a += (double)(op->Prev->Pt.X + op->Pt.X) *
+         (double)(op->Prev->Pt.Y - op->Pt.Y);
+    op = op->Next;
+  } while (op != startOp);
+  return a * 0.5;
+}
+//------------------------------------------------------------------------------
+
+double Area(const OutRec &outRec) { return Area(outRec.Pts); }
+//------------------------------------------------------------------------------
+
+bool PointIsVertex(const IntPoint &Pt, OutPt *pp) {
+  OutPt *pp2 = pp;
+  do {
+    if (pp2->Pt == Pt)
+      return true;
+    pp2 = pp2->Next;
+  } while (pp2 != pp);
+  return false;
+}
+//------------------------------------------------------------------------------
+
+// See "The Point in Polygon Problem for Arbitrary Polygons" by Hormann &
+// Agathos
+// http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.88.5498&rep=rep1&type=pdf
+int PointInPolygon(const IntPoint &pt, const Path &path) {
+  // returns 0 if false, +1 if true, -1 if pt ON polygon boundary
+  int result = 0;
+  size_t cnt = path.size();
+  if (cnt < 3)
+    return 0;
+  IntPoint ip = path[0];
+  for (size_t i = 1; i <= cnt; ++i) {
+    IntPoint ipNext = (i == cnt ? path[0] : path[i]);
+    if (ipNext.Y == pt.Y) {
+      if ((ipNext.X == pt.X) ||
+          (ip.Y == pt.Y && ((ipNext.X > pt.X) == (ip.X < pt.X))))
+        return -1;
+    }
+    if ((ip.Y < pt.Y) != (ipNext.Y < pt.Y)) {
+      if (ip.X >= pt.X) {
+        if (ipNext.X > pt.X)
+          result = 1 - result;
+        else {
+          double d = (double)(ip.X - pt.X) * (ipNext.Y - pt.Y) -
+                     (double)(ipNext.X - pt.X) * (ip.Y - pt.Y);
+          if (!d)
+            return -1;
+          if ((d > 0) == (ipNext.Y > ip.Y))
+            result = 1 - result;
+        }
+      } else {
+        if (ipNext.X > pt.X) {
+          double d = (double)(ip.X - pt.X) * (ipNext.Y - pt.Y) -
+                     (double)(ipNext.X - pt.X) * (ip.Y - pt.Y);
+          if (!d)
+            return -1;
+          if ((d > 0) == (ipNext.Y > ip.Y))
+            result = 1 - result;
+        }
+      }
+    }
+    ip = ipNext;
+  }
+  return result;
+}
+//------------------------------------------------------------------------------
+
+int PointInPolygon(const IntPoint &pt, OutPt *op) {
+  // returns 0 if false, +1 if true, -1 if pt ON polygon boundary
+  int result = 0;
+  OutPt *startOp = op;
+  for (;;) {
+    if (op->Next->Pt.Y == pt.Y) {
+      if ((op->Next->Pt.X == pt.X) ||
+          (op->Pt.Y == pt.Y && ((op->Next->Pt.X > pt.X) == (op->Pt.X < pt.X))))
+        return -1;
+    }
+    if ((op->Pt.Y < pt.Y) != (op->Next->Pt.Y < pt.Y)) {
+      if (op->Pt.X >= pt.X) {
+        if (op->Next->Pt.X > pt.X)
+          result = 1 - result;
+        else {
+          double d = (double)(op->Pt.X - pt.X) * (op->Next->Pt.Y - pt.Y) -
+                     (double)(op->Next->Pt.X - pt.X) * (op->Pt.Y - pt.Y);
+          if (!d)
+            return -1;
+          if ((d > 0) == (op->Next->Pt.Y > op->Pt.Y))
+            result = 1 - result;
+        }
+      } else {
+        if (op->Next->Pt.X > pt.X) {
+          double d = (double)(op->Pt.X - pt.X) * (op->Next->Pt.Y - pt.Y) -
+                     (double)(op->Next->Pt.X - pt.X) * (op->Pt.Y - pt.Y);
+          if (!d)
+            return -1;
+          if ((d > 0) == (op->Next->Pt.Y > op->Pt.Y))
+            result = 1 - result;
+        }
+      }
+    }
+    op = op->Next;
+    if (startOp == op)
+      break;
+  }
+  return result;
+}
+//------------------------------------------------------------------------------
+
+bool Poly2ContainsPoly1(OutPt *OutPt1, OutPt *OutPt2) {
+  OutPt *op = OutPt1;
+  do {
+    // nb: PointInPolygon returns 0 if false, +1 if true, -1 if pt on polygon
+    int res = PointInPolygon(op->Pt, OutPt2);
+    if (res >= 0)
+      return res > 0;
+    op = op->Next;
+  } while (op != OutPt1);
+  return true;
+}
+//----------------------------------------------------------------------
+
+bool SlopesEqual(const TEdge &e1, const TEdge &e2, bool UseFullInt64Range) {
+#ifndef use_int32
+  if (UseFullInt64Range)
+    return Int128Mul(e1.Top.Y - e1.Bot.Y, e2.Top.X - e2.Bot.X) ==
+           Int128Mul(e1.Top.X - e1.Bot.X, e2.Top.Y - e2.Bot.Y);
+  else
+#endif
+    return (e1.Top.Y - e1.Bot.Y) * (e2.Top.X - e2.Bot.X) ==
+           (e1.Top.X - e1.Bot.X) * (e2.Top.Y - e2.Bot.Y);
+}
+//------------------------------------------------------------------------------
+
+bool SlopesEqual(const IntPoint pt1, const IntPoint pt2, const IntPoint pt3,
+                 bool UseFullInt64Range) {
+#ifndef use_int32
+  if (UseFullInt64Range)
+    return Int128Mul(pt1.Y - pt2.Y, pt2.X - pt3.X) ==
+           Int128Mul(pt1.X - pt2.X, pt2.Y - pt3.Y);
+  else
+#endif
+    return (pt1.Y - pt2.Y) * (pt2.X - pt3.X) ==
+           (pt1.X - pt2.X) * (pt2.Y - pt3.Y);
+}
+//------------------------------------------------------------------------------
+
+bool SlopesEqual(const IntPoint pt1, const IntPoint pt2, const IntPoint pt3,
+                 const IntPoint pt4, bool UseFullInt64Range) {
+#ifndef use_int32
+  if (UseFullInt64Range)
+    return Int128Mul(pt1.Y - pt2.Y, pt3.X - pt4.X) ==
+           Int128Mul(pt1.X - pt2.X, pt3.Y - pt4.Y);
+  else
+#endif
+    return (pt1.Y - pt2.Y) * (pt3.X - pt4.X) ==
+           (pt1.X - pt2.X) * (pt3.Y - pt4.Y);
+}
+//------------------------------------------------------------------------------
+
+inline bool IsHorizontal(TEdge &e) { return e.Dx == HORIZONTAL; }
+//------------------------------------------------------------------------------
+
+inline double GetDx(const IntPoint pt1, const IntPoint pt2) {
+  return (pt1.Y == pt2.Y) ? HORIZONTAL
+                          : (double)(pt2.X - pt1.X) / (pt2.Y - pt1.Y);
+}
+//---------------------------------------------------------------------------
+
+inline void SetDx(TEdge &e) {
+  cInt dy = (e.Top.Y - e.Bot.Y);
+  if (dy == 0)
+    e.Dx = HORIZONTAL;
+  else
+    e.Dx = (double)(e.Top.X - e.Bot.X) / dy;
+}
+//---------------------------------------------------------------------------
+
+inline void SwapSides(TEdge &Edge1, TEdge &Edge2) {
+  EdgeSide Side = Edge1.Side;
+  Edge1.Side = Edge2.Side;
+  Edge2.Side = Side;
+}
+//------------------------------------------------------------------------------
+
+inline void SwapPolyIndexes(TEdge &Edge1, TEdge &Edge2) {
+  int OutIdx = Edge1.OutIdx;
+  Edge1.OutIdx = Edge2.OutIdx;
+  Edge2.OutIdx = OutIdx;
+}
+//------------------------------------------------------------------------------
+
+inline cInt TopX(TEdge &edge, const cInt currentY) {
+  return (currentY == edge.Top.Y)
+             ? edge.Top.X
+             : edge.Bot.X + Round(edge.Dx * (currentY - edge.Bot.Y));
+}
+//------------------------------------------------------------------------------
+
+void IntersectPoint(TEdge &Edge1, TEdge &Edge2, IntPoint &ip) {
+#ifdef use_xyz
+  ip.Z = 0;
+#endif
+
+  double b1, b2;
+  if (Edge1.Dx == Edge2.Dx) {
+    ip.Y = Edge1.Curr.Y;
+    ip.X = TopX(Edge1, ip.Y);
+    return;
+  } else if (Edge1.Dx == 0) {
+    ip.X = Edge1.Bot.X;
+    if (IsHorizontal(Edge2))
+      ip.Y = Edge2.Bot.Y;
+    else {
+      b2 = Edge2.Bot.Y - (Edge2.Bot.X / Edge2.Dx);
+      ip.Y = Round(ip.X / Edge2.Dx + b2);
+    }
+  } else if (Edge2.Dx == 0) {
+    ip.X = Edge2.Bot.X;
+    if (IsHorizontal(Edge1))
+      ip.Y = Edge1.Bot.Y;
+    else {
+      b1 = Edge1.Bot.Y - (Edge1.Bot.X / Edge1.Dx);
+      ip.Y = Round(ip.X / Edge1.Dx + b1);
+    }
+  } else {
+    b1 = Edge1.Bot.X - Edge1.Bot.Y * Edge1.Dx;
+    b2 = Edge2.Bot.X - Edge2.Bot.Y * Edge2.Dx;
+    double q = (b2 - b1) / (Edge1.Dx - Edge2.Dx);
+    ip.Y = Round(q);
+    if (std::fabs(Edge1.Dx) < std::fabs(Edge2.Dx))
+      ip.X = Round(Edge1.Dx * q + b1);
+    else
+      ip.X = Round(Edge2.Dx * q + b2);
+  }
+
+  if (ip.Y < Edge1.Top.Y || ip.Y < Edge2.Top.Y) {
+    if (Edge1.Top.Y > Edge2.Top.Y)
+      ip.Y = Edge1.Top.Y;
+    else
+      ip.Y = Edge2.Top.Y;
+    if (std::fabs(Edge1.Dx) < std::fabs(Edge2.Dx))
+      ip.X = TopX(Edge1, ip.Y);
+    else
+      ip.X = TopX(Edge2, ip.Y);
+  }
+  // finally, don't allow 'ip' to be BELOW curr.Y (ie bottom of scanbeam) ...
+  if (ip.Y > Edge1.Curr.Y) {
+    ip.Y = Edge1.Curr.Y;
+    // use the more vertical edge to derive X ...
+    if (std::fabs(Edge1.Dx) > std::fabs(Edge2.Dx))
+      ip.X = TopX(Edge2, ip.Y);
+    else
+      ip.X = TopX(Edge1, ip.Y);
+  }
+}
+//------------------------------------------------------------------------------
+
+void ReversePolyPtLinks(OutPt *pp) {
+  if (!pp)
+    return;
+  OutPt *pp1, *pp2;
+  pp1 = pp;
+  do {
+    pp2 = pp1->Next;
+    pp1->Next = pp1->Prev;
+    pp1->Prev = pp2;
+    pp1 = pp2;
+  } while (pp1 != pp);
+}
+//------------------------------------------------------------------------------
+
+void DisposeOutPts(OutPt *&pp) {
+  if (pp == 0)
+    return;
+  pp->Prev->Next = 0;
+  while (pp) {
+    OutPt *tmpPp = pp;
+    pp = pp->Next;
+    delete tmpPp;
+  }
+}
+//------------------------------------------------------------------------------
+
+inline void InitEdge(TEdge *e, TEdge *eNext, TEdge *ePrev, const IntPoint &Pt) {
+  std::memset(e, 0, sizeof(TEdge));
+  e->Next = eNext;
+  e->Prev = ePrev;
+  e->Curr = Pt;
+  e->OutIdx = Unassigned;
+}
+//------------------------------------------------------------------------------
+
+void InitEdge2(TEdge &e, PolyType Pt) {
+  if (e.Curr.Y >= e.Next->Curr.Y) {
+    e.Bot = e.Curr;
+    e.Top = e.Next->Curr;
+  } else {
+    e.Top = e.Curr;
+    e.Bot = e.Next->Curr;
+  }
+  SetDx(e);
+  e.PolyTyp = Pt;
+}
+//------------------------------------------------------------------------------
+
+TEdge *RemoveEdge(TEdge *e) {
+  // removes e from double_linked_list (but without removing from memory)
+  e->Prev->Next = e->Next;
+  e->Next->Prev = e->Prev;
+  TEdge *result = e->Next;
+  e->Prev = 0; // flag as removed (see ClipperBase.Clear)
+  return result;
+}
+//------------------------------------------------------------------------------
+
+inline void ReverseHorizontal(TEdge &e) {
+  // swap horizontal edges' Top and Bottom x's so they follow the natural
+  // progression of the bounds - ie so their xbots will align with the
+  // adjoining lower edge. [Helpful in the ProcessHorizontal() method.]
+  std::swap(e.Top.X, e.Bot.X);
+#ifdef use_xyz
+  std::swap(e.Top.Z, e.Bot.Z);
+#endif
+}
+//------------------------------------------------------------------------------
+
+void SwapPoints(IntPoint &pt1, IntPoint &pt2) {
+  IntPoint tmp = pt1;
+  pt1 = pt2;
+  pt2 = tmp;
+}
+//------------------------------------------------------------------------------
+
+bool GetOverlapSegment(IntPoint pt1a, IntPoint pt1b, IntPoint pt2a,
+                       IntPoint pt2b, IntPoint &pt1, IntPoint &pt2) {
+  // precondition: segments are Collinear.
+  if (Abs(pt1a.X - pt1b.X) > Abs(pt1a.Y - pt1b.Y)) {
+    if (pt1a.X > pt1b.X)
+      SwapPoints(pt1a, pt1b);
+    if (pt2a.X > pt2b.X)
+      SwapPoints(pt2a, pt2b);
+    if (pt1a.X > pt2a.X)
+      pt1 = pt1a;
+    else
+      pt1 = pt2a;
+    if (pt1b.X < pt2b.X)
+      pt2 = pt1b;
+    else
+      pt2 = pt2b;
+    return pt1.X < pt2.X;
+  } else {
+    if (pt1a.Y < pt1b.Y)
+      SwapPoints(pt1a, pt1b);
+    if (pt2a.Y < pt2b.Y)
+      SwapPoints(pt2a, pt2b);
+    if (pt1a.Y < pt2a.Y)
+      pt1 = pt1a;
+    else
+      pt1 = pt2a;
+    if (pt1b.Y > pt2b.Y)
+      pt2 = pt1b;
+    else
+      pt2 = pt2b;
+    return pt1.Y > pt2.Y;
+  }
+}
+//------------------------------------------------------------------------------
+
+bool FirstIsBottomPt(const OutPt *btmPt1, const OutPt *btmPt2) {
+  OutPt *p = btmPt1->Prev;
+  while ((p->Pt == btmPt1->Pt) && (p != btmPt1))
+    p = p->Prev;
+  double dx1p = std::fabs(GetDx(btmPt1->Pt, p->Pt));
+  p = btmPt1->Next;
+  while ((p->Pt == btmPt1->Pt) && (p != btmPt1))
+    p = p->Next;
+  double dx1n = std::fabs(GetDx(btmPt1->Pt, p->Pt));
+
+  p = btmPt2->Prev;
+  while ((p->Pt == btmPt2->Pt) && (p != btmPt2))
+    p = p->Prev;
+  double dx2p = std::fabs(GetDx(btmPt2->Pt, p->Pt));
+  p = btmPt2->Next;
+  while ((p->Pt == btmPt2->Pt) && (p != btmPt2))
+    p = p->Next;
+  double dx2n = std::fabs(GetDx(btmPt2->Pt, p->Pt));
+
+  if (std::max(dx1p, dx1n) == std::max(dx2p, dx2n) &&
+      std::min(dx1p, dx1n) == std::min(dx2p, dx2n))
+    return Area(btmPt1) > 0; // if otherwise identical use orientation
+  else
+    return (dx1p >= dx2p && dx1p >= dx2n) || (dx1n >= dx2p && dx1n >= dx2n);
+}
+//------------------------------------------------------------------------------
+
+OutPt *GetBottomPt(OutPt *pp) {
+  OutPt *dups = 0;
+  OutPt *p = pp->Next;
+  while (p != pp) {
+    if (p->Pt.Y > pp->Pt.Y) {
+      pp = p;
+      dups = 0;
+    } else if (p->Pt.Y == pp->Pt.Y && p->Pt.X <= pp->Pt.X) {
+      if (p->Pt.X < pp->Pt.X) {
+        dups = 0;
+        pp = p;
+      } else {
+        if (p->Next != pp && p->Prev != pp)
+          dups = p;
+      }
+    }
+    p = p->Next;
+  }
+  if (dups) {
+    // there appears to be at least 2 vertices at BottomPt so ...
+    while (dups != p) {
+      if (!FirstIsBottomPt(p, dups))
+        pp = dups;
+      dups = dups->Next;
+      while (dups->Pt != pp->Pt)
+        dups = dups->Next;
+    }
+  }
+  return pp;
+}
+//------------------------------------------------------------------------------
+
+bool Pt2IsBetweenPt1AndPt3(const IntPoint pt1, const IntPoint pt2,
+                           const IntPoint pt3) {
+  if ((pt1 == pt3) || (pt1 == pt2) || (pt3 == pt2))
+    return false;
+  else if (pt1.X != pt3.X)
+    return (pt2.X > pt1.X) == (pt2.X < pt3.X);
+  else
+    return (pt2.Y > pt1.Y) == (pt2.Y < pt3.Y);
+}
+//------------------------------------------------------------------------------
+
+bool HorzSegmentsOverlap(cInt seg1a, cInt seg1b, cInt seg2a, cInt seg2b) {
+  if (seg1a > seg1b)
+    std::swap(seg1a, seg1b);
+  if (seg2a > seg2b)
+    std::swap(seg2a, seg2b);
+  return (seg1a < seg2b) && (seg2a < seg1b);
+}
+
+//------------------------------------------------------------------------------
+// ClipperBase class methods ...
+//------------------------------------------------------------------------------
+
+ClipperBase::ClipperBase() // constructor
+{
+  m_CurrentLM = m_MinimaList.begin(); // begin() == end() here
+  m_UseFullRange = false;
+}
+//------------------------------------------------------------------------------
+
+ClipperBase::~ClipperBase() // destructor
+{
+  Clear();
+}
+//------------------------------------------------------------------------------
+
+void RangeTest(const IntPoint &Pt, bool &useFullRange) {
+  if (useFullRange) {
+    if (Pt.X > hiRange || Pt.Y > hiRange || -Pt.X > hiRange || -Pt.Y > hiRange)
+      throw clipperException("Coordinate outside allowed range");
+  } else if (Pt.X > loRange || Pt.Y > loRange || -Pt.X > loRange ||
+             -Pt.Y > loRange) {
+    useFullRange = true;
+    RangeTest(Pt, useFullRange);
+  }
+}
+//------------------------------------------------------------------------------
+
+TEdge *FindNextLocMin(TEdge *E) {
+  for (;;) {
+    while (E->Bot != E->Prev->Bot || E->Curr == E->Top)
+      E = E->Next;
+    if (!IsHorizontal(*E) && !IsHorizontal(*E->Prev))
+      break;
+    while (IsHorizontal(*E->Prev))
+      E = E->Prev;
+    TEdge *E2 = E;
+    while (IsHorizontal(*E))
+      E = E->Next;
+    if (E->Top.Y == E->Prev->Bot.Y)
+      continue; // ie just an intermediate horz.
+    if (E2->Prev->Bot.X < E->Bot.X)
+      E = E2;
+    break;
+  }
+  return E;
+}
+//------------------------------------------------------------------------------
+
+TEdge *ClipperBase::ProcessBound(TEdge *E, bool NextIsForward) {
+  TEdge *Result = E;
+  TEdge *Horz = 0;
+
+  if (E->OutIdx == Skip) {
+    // if edges still remain in the current bound beyond the skip edge then
+    // create another LocMin and call ProcessBound once more
+    if (NextIsForward) {
+      while (E->Top.Y == E->Next->Bot.Y)
+        E = E->Next;
+      // don't include top horizontals when parsing a bound a second time,
+      // they will be contained in the opposite bound ...
+      while (E != Result && IsHorizontal(*E))
+        E = E->Prev;
+    } else {
+      while (E->Top.Y == E->Prev->Bot.Y)
+        E = E->Prev;
+      while (E != Result && IsHorizontal(*E))
+        E = E->Next;
+    }
+
+    if (E == Result) {
+      if (NextIsForward)
+        Result = E->Next;
+      else
+        Result = E->Prev;
+    } else {
+      // there are more edges in the bound beyond result starting with E
+      if (NextIsForward)
+        E = Result->Next;
+      else
+        E = Result->Prev;
+      MinimaList::value_type locMin;
+      locMin.Y = E->Bot.Y;
+      locMin.LeftBound = 0;
+      locMin.RightBound = E;
+      E->WindDelta = 0;
+      Result = ProcessBound(E, NextIsForward);
+      m_MinimaList.push_back(locMin);
+    }
+    return Result;
+  }
+
+  TEdge *EStart;
+
+  if (IsHorizontal(*E)) {
+    // We need to be careful with open paths because this may not be a
+    // true local minima (ie E may be following a skip edge).
+    // Also, consecutive horz. edges may start heading left before going right.
+    if (NextIsForward)
+      EStart = E->Prev;
+    else
+      EStart = E->Next;
+    if (IsHorizontal(*EStart)) // ie an adjoining horizontal skip edge
+    {
+      if (EStart->Bot.X != E->Bot.X && EStart->Top.X != E->Bot.X)
+        ReverseHorizontal(*E);
+    } else if (EStart->Bot.X != E->Bot.X)
+      ReverseHorizontal(*E);
+  }
+
+  EStart = E;
+  if (NextIsForward) {
+    while (Result->Top.Y == Result->Next->Bot.Y && Result->Next->OutIdx != Skip)
+      Result = Result->Next;
+    if (IsHorizontal(*Result) && Result->Next->OutIdx != Skip) {
+      // nb: at the top of a bound, horizontals are added to the bound
+      // only when the preceding edge attaches to the horizontal's left vertex
+      // unless a Skip edge is encountered when that becomes the top divide
+      Horz = Result;
+      while (IsHorizontal(*Horz->Prev))
+        Horz = Horz->Prev;
+      if (Horz->Prev->Top.X > Result->Next->Top.X)
+        Result = Horz->Prev;
+    }
+    while (E != Result) {
+      E->NextInLML = E->Next;
+      if (IsHorizontal(*E) && E != EStart && E->Bot.X != E->Prev->Top.X)
+        ReverseHorizontal(*E);
+      E = E->Next;
+    }
+    if (IsHorizontal(*E) && E != EStart && E->Bot.X != E->Prev->Top.X)
+      ReverseHorizontal(*E);
+    Result = Result->Next; // move to the edge just beyond current bound
+  } else {
+    while (Result->Top.Y == Result->Prev->Bot.Y && Result->Prev->OutIdx != Skip)
+      Result = Result->Prev;
+    if (IsHorizontal(*Result) && Result->Prev->OutIdx != Skip) {
+      Horz = Result;
+      while (IsHorizontal(*Horz->Next))
+        Horz = Horz->Next;
+      if (Horz->Next->Top.X == Result->Prev->Top.X ||
+          Horz->Next->Top.X > Result->Prev->Top.X)
+        Result = Horz->Next;
+    }
+
+    while (E != Result) {
+      E->NextInLML = E->Prev;
+      if (IsHorizontal(*E) && E != EStart && E->Bot.X != E->Next->Top.X)
+        ReverseHorizontal(*E);
+      E = E->Prev;
+    }
+    if (IsHorizontal(*E) && E != EStart && E->Bot.X != E->Next->Top.X)
+      ReverseHorizontal(*E);
+    Result = Result->Prev; // move to the edge just beyond current bound
+  }
+
+  return Result;
+}
+//------------------------------------------------------------------------------
+
+bool ClipperBase::AddPath(const Path &pg, PolyType PolyTyp, bool Closed) {
+#ifdef use_lines
+  if (!Closed && PolyTyp == ptClip)
+    throw clipperException("AddPath: Open paths must be subject.");
+#else
+  if (!Closed)
+    throw clipperException("AddPath: Open paths have been disabled.");
+#endif
+
+  int highI = (int)pg.size() - 1;
+  if (Closed)
+    while (highI > 0 && (pg[highI] == pg[0]))
+      --highI;
+  while (highI > 0 && (pg[highI] == pg[highI - 1]))
+    --highI;
+  if ((Closed && highI < 2) || (!Closed && highI < 1))
+    return false;
+
+  // create a new edge array ...
+  TEdge *edges = new TEdge[highI + 1];
+
+  bool IsFlat = true;
+  // 1. Basic (first) edge initialization ...
+  try {
+    edges[1].Curr = pg[1];
+    RangeTest(pg[0], m_UseFullRange);
+    RangeTest(pg[highI], m_UseFullRange);
+    InitEdge(&edges[0], &edges[1], &edges[highI], pg[0]);
+    InitEdge(&edges[highI], &edges[0], &edges[highI - 1], pg[highI]);
+    for (int i = highI - 1; i >= 1; --i) {
+      RangeTest(pg[i], m_UseFullRange);
+      InitEdge(&edges[i], &edges[i + 1], &edges[i - 1], pg[i]);
+    }
+  } catch (...) {
+    delete[] edges;
+    throw; // range test fails
+  }
+  TEdge *eStart = &edges[0];
+
+  // 2. Remove duplicate vertices, and (when closed) collinear edges ...
+  TEdge *E = eStart, *eLoopStop = eStart;
+  for (;;) {
+    // nb: allows matching start and end points when not Closed ...
+    if (E->Curr == E->Next->Curr && (Closed || E->Next != eStart)) {
+      if (E == E->Next)
+        break;
+      if (E == eStart)
+        eStart = E->Next;
+      E = RemoveEdge(E);
+      eLoopStop = E;
+      continue;
+    }
+    if (E->Prev == E->Next)
+      break; // only two vertices
+    else if (Closed && SlopesEqual(E->Prev->Curr, E->Curr, E->Next->Curr,
+                                   m_UseFullRange) &&
+             (!m_PreserveCollinear ||
+              !Pt2IsBetweenPt1AndPt3(E->Prev->Curr, E->Curr, E->Next->Curr))) {
+      // Collinear edges are allowed for open paths but in closed paths
+      // the default is to merge adjacent collinear edges into a single edge.
+      // However, if the PreserveCollinear property is enabled, only overlapping
+      // collinear edges (ie spikes) will be removed from closed paths.
+      if (E == eStart)
+        eStart = E->Next;
+      E = RemoveEdge(E);
+      E = E->Prev;
+      eLoopStop = E;
+      continue;
+    }
+    E = E->Next;
+    if ((E == eLoopStop) || (!Closed && E->Next == eStart))
+      break;
+  }
+
+  if ((!Closed && (E == E->Next)) || (Closed && (E->Prev == E->Next))) {
+    delete[] edges;
+    return false;
+  }
+
+  if (!Closed) {
+    m_HasOpenPaths = true;
+    eStart->Prev->OutIdx = Skip;
+  }
+
+  // 3. Do second stage of edge initialization ...
+  E = eStart;
+  do {
+    InitEdge2(*E, PolyTyp);
+    E = E->Next;
+    if (IsFlat && E->Curr.Y != eStart->Curr.Y)
+      IsFlat = false;
+  } while (E != eStart);
+
+  // 4. Finally, add edge bounds to LocalMinima list ...
+
+  // Totally flat paths must be handled differently when adding them
+  // to LocalMinima list to avoid endless loops etc ...
+  if (IsFlat) {
+    if (Closed) {
+      delete[] edges;
+      return false;
+    }
+    E->Prev->OutIdx = Skip;
+    MinimaList::value_type locMin;
+    locMin.Y = E->Bot.Y;
+    locMin.LeftBound = 0;
+    locMin.RightBound = E;
+    locMin.RightBound->Side = esRight;
+    locMin.RightBound->WindDelta = 0;
+    for (;;) {
+      if (E->Bot.X != E->Prev->Top.X)
+        ReverseHorizontal(*E);
+      if (E->Next->OutIdx == Skip)
+        break;
+      E->NextInLML = E->Next;
+      E = E->Next;
+    }
+    m_MinimaList.push_back(locMin);
+    m_edges.push_back(edges);
+    return true;
+  }
+
+  m_edges.push_back(edges);
+  bool leftBoundIsForward;
+  TEdge *EMin = 0;
+
+  // workaround to avoid an endless loop in the while loop below when
+  // open paths have matching start and end points ...
+  if (E->Prev->Bot == E->Prev->Top)
+    E = E->Next;
+
+  for (;;) {
+    E = FindNextLocMin(E);
+    if (E == EMin)
+      break;
+    else if (!EMin)
+      EMin = E;
+
+    // E and E.Prev now share a local minima (left aligned if horizontal).
+    // Compare their slopes to find which starts which bound ...
+    MinimaList::value_type locMin;
+    locMin.Y = E->Bot.Y;
+    if (E->Dx < E->Prev->Dx) {
+      locMin.LeftBound = E->Prev;
+      locMin.RightBound = E;
+      leftBoundIsForward = false; // Q.nextInLML = Q.prev
+    } else {
+      locMin.LeftBound = E;
+      locMin.RightBound = E->Prev;
+      leftBoundIsForward = true; // Q.nextInLML = Q.next
+    }
+
+    if (!Closed)
+      locMin.LeftBound->WindDelta = 0;
+    else if (locMin.LeftBound->Next == locMin.RightBound)
+      locMin.LeftBound->WindDelta = -1;
+    else
+      locMin.LeftBound->WindDelta = 1;
+    locMin.RightBound->WindDelta = -locMin.LeftBound->WindDelta;
+
+    E = ProcessBound(locMin.LeftBound, leftBoundIsForward);
+    if (E->OutIdx == Skip)
+      E = ProcessBound(E, leftBoundIsForward);
+
+    TEdge *E2 = ProcessBound(locMin.RightBound, !leftBoundIsForward);
+    if (E2->OutIdx == Skip)
+      E2 = ProcessBound(E2, !leftBoundIsForward);
+
+    if (locMin.LeftBound->OutIdx == Skip)
+      locMin.LeftBound = 0;
+    else if (locMin.RightBound->OutIdx == Skip)
+      locMin.RightBound = 0;
+    m_MinimaList.push_back(locMin);
+    if (!leftBoundIsForward)
+      E = E2;
+  }
+  return true;
+}
+//------------------------------------------------------------------------------
+
+bool ClipperBase::AddPaths(const Paths &ppg, PolyType PolyTyp, bool Closed) {
+  bool result = false;
+  for (Paths::size_type i = 0; i < ppg.size(); ++i)
+    if (AddPath(ppg[i], PolyTyp, Closed))
+      result = true;
+  return result;
+}
+//------------------------------------------------------------------------------
+
+void ClipperBase::Clear() {
+  DisposeLocalMinimaList();
+  for (EdgeList::size_type i = 0; i < m_edges.size(); ++i) {
+    TEdge *edges = m_edges[i];
+    delete[] edges;
+  }
+  m_edges.clear();
+  m_UseFullRange = false;
+  m_HasOpenPaths = false;
+}
+//------------------------------------------------------------------------------
+
+void ClipperBase::Reset() {
+  m_CurrentLM = m_MinimaList.begin();
+  if (m_CurrentLM == m_MinimaList.end())
+    return; // ie nothing to process
+  std::sort(m_MinimaList.begin(), m_MinimaList.end(), LocMinSorter());
+
+  m_Scanbeam = ScanbeamList(); // clears/resets priority_queue
+  // reset all edges ...
+  for (MinimaList::iterator lm = m_MinimaList.begin(); lm != m_MinimaList.end();
+       ++lm) {
+    InsertScanbeam(lm->Y);
+    TEdge *e = lm->LeftBound;
+    if (e) {
+      e->Curr = e->Bot;
+      e->Side = esLeft;
+      e->OutIdx = Unassigned;
+    }
+
+    e = lm->RightBound;
+    if (e) {
+      e->Curr = e->Bot;
+      e->Side = esRight;
+      e->OutIdx = Unassigned;
+    }
+  }
+  m_ActiveEdges = 0;
+  m_CurrentLM = m_MinimaList.begin();
+}
+//------------------------------------------------------------------------------
+
+void ClipperBase::DisposeLocalMinimaList() {
+  m_MinimaList.clear();
+  m_CurrentLM = m_MinimaList.begin();
+}
+//------------------------------------------------------------------------------
+
+bool ClipperBase::PopLocalMinima(cInt Y, const LocalMinimum *&locMin) {
+  if (m_CurrentLM == m_MinimaList.end() || (*m_CurrentLM).Y != Y)
+    return false;
+  locMin = &(*m_CurrentLM);
+  ++m_CurrentLM;
+  return true;
+}
+//------------------------------------------------------------------------------
+
+IntRect ClipperBase::GetBounds() {
+  IntRect result;
+  MinimaList::iterator lm = m_MinimaList.begin();
+  if (lm == m_MinimaList.end()) {
+    result.left = result.top = result.right = result.bottom = 0;
+    return result;
+  }
+  result.left = lm->LeftBound->Bot.X;
+  result.top = lm->LeftBound->Bot.Y;
+  result.right = lm->LeftBound->Bot.X;
+  result.bottom = lm->LeftBound->Bot.Y;
+  while (lm != m_MinimaList.end()) {
+    // todo - needs fixing for open paths
+    result.bottom = std::max(result.bottom, lm->LeftBound->Bot.Y);
+    TEdge *e = lm->LeftBound;
+    for (;;) {
+      TEdge *bottomE = e;
+      while (e->NextInLML) {
+        if (e->Bot.X < result.left)
+          result.left = e->Bot.X;
+        if (e->Bot.X > result.right)
+          result.right = e->Bot.X;
+        e = e->NextInLML;
+      }
+      result.left = std::min(result.left, e->Bot.X);
+      result.right = std::max(result.right, e->Bot.X);
+      result.left = std::min(result.left, e->Top.X);
+      result.right = std::max(result.right, e->Top.X);
+      result.top = std::min(result.top, e->Top.Y);
+      if (bottomE == lm->LeftBound)
+        e = lm->RightBound;
+      else
+        break;
+    }
+    ++lm;
+  }
+  return result;
+}
+//------------------------------------------------------------------------------
+
+void ClipperBase::InsertScanbeam(const cInt Y) { m_Scanbeam.push(Y); }
+//------------------------------------------------------------------------------
+
+bool ClipperBase::PopScanbeam(cInt &Y) {
+  if (m_Scanbeam.empty())
+    return false;
+  Y = m_Scanbeam.top();
+  m_Scanbeam.pop();
+  while (!m_Scanbeam.empty() && Y == m_Scanbeam.top()) {
+    m_Scanbeam.pop();
+  } // Pop duplicates.
+  return true;
+}
+//------------------------------------------------------------------------------
+
+void ClipperBase::DisposeAllOutRecs() {
+  for (PolyOutList::size_type i = 0; i < m_PolyOuts.size(); ++i)
+    DisposeOutRec(i);
+  m_PolyOuts.clear();
+}
+//------------------------------------------------------------------------------
+
+void ClipperBase::DisposeOutRec(PolyOutList::size_type index) {
+  OutRec *outRec = m_PolyOuts[index];
+  if (outRec->Pts)
+    DisposeOutPts(outRec->Pts);
+  delete outRec;
+  m_PolyOuts[index] = 0;
+}
+//------------------------------------------------------------------------------
+
+void ClipperBase::DeleteFromAEL(TEdge *e) {
+  TEdge *AelPrev = e->PrevInAEL;
+  TEdge *AelNext = e->NextInAEL;
+  if (!AelPrev && !AelNext && (e != m_ActiveEdges))
+    return; // already deleted
+  if (AelPrev)
+    AelPrev->NextInAEL = AelNext;
+  else
+    m_ActiveEdges = AelNext;
+  if (AelNext)
+    AelNext->PrevInAEL = AelPrev;
+  e->NextInAEL = 0;
+  e->PrevInAEL = 0;
+}
+//------------------------------------------------------------------------------
+
+OutRec *ClipperBase::CreateOutRec() {
+  OutRec *result = new OutRec;
+  result->IsHole = false;
+  result->IsOpen = false;
+  result->FirstLeft = 0;
+  result->Pts = 0;
+  result->BottomPt = 0;
+  result->PolyNd = 0;
+  m_PolyOuts.push_back(result);
+  result->Idx = (int)m_PolyOuts.size() - 1;
+  return result;
+}
+//------------------------------------------------------------------------------
+
+void ClipperBase::SwapPositionsInAEL(TEdge *Edge1, TEdge *Edge2) {
+  // check that one or other edge hasn't already been removed from AEL ...
+  if (Edge1->NextInAEL == Edge1->PrevInAEL ||
+      Edge2->NextInAEL == Edge2->PrevInAEL)
+    return;
+
+  if (Edge1->NextInAEL == Edge2) {
+    TEdge *Next = Edge2->NextInAEL;
+    if (Next)
+      Next->PrevInAEL = Edge1;
+    TEdge *Prev = Edge1->PrevInAEL;
+    if (Prev)
+      Prev->NextInAEL = Edge2;
+    Edge2->PrevInAEL = Prev;
+    Edge2->NextInAEL = Edge1;
+    Edge1->PrevInAEL = Edge2;
+    Edge1->NextInAEL = Next;
+  } else if (Edge2->NextInAEL == Edge1) {
+    TEdge *Next = Edge1->NextInAEL;
+    if (Next)
+      Next->PrevInAEL = Edge2;
+    TEdge *Prev = Edge2->PrevInAEL;
+    if (Prev)
+      Prev->NextInAEL = Edge1;
+    Edge1->PrevInAEL = Prev;
+    Edge1->NextInAEL = Edge2;
+    Edge2->PrevInAEL = Edge1;
+    Edge2->NextInAEL = Next;
+  } else {
+    TEdge *Next = Edge1->NextInAEL;
+    TEdge *Prev = Edge1->PrevInAEL;
+    Edge1->NextInAEL = Edge2->NextInAEL;
+    if (Edge1->NextInAEL)
+      Edge1->NextInAEL->PrevInAEL = Edge1;
+    Edge1->PrevInAEL = Edge2->PrevInAEL;
+    if (Edge1->PrevInAEL)
+      Edge1->PrevInAEL->NextInAEL = Edge1;
+    Edge2->NextInAEL = Next;
+    if (Edge2->NextInAEL)
+      Edge2->NextInAEL->PrevInAEL = Edge2;
+    Edge2->PrevInAEL = Prev;
+    if (Edge2->PrevInAEL)
+      Edge2->PrevInAEL->NextInAEL = Edge2;
+  }
+
+  if (!Edge1->PrevInAEL)
+    m_ActiveEdges = Edge1;
+  else if (!Edge2->PrevInAEL)
+    m_ActiveEdges = Edge2;
+}
+//------------------------------------------------------------------------------
+
+void ClipperBase::UpdateEdgeIntoAEL(TEdge *&e) {
+  if (!e->NextInLML)
+    throw clipperException("UpdateEdgeIntoAEL: invalid call");
+
+  e->NextInLML->OutIdx = e->OutIdx;
+  TEdge *AelPrev = e->PrevInAEL;
+  TEdge *AelNext = e->NextInAEL;
+  if (AelPrev)
+    AelPrev->NextInAEL = e->NextInLML;
+  else
+    m_ActiveEdges = e->NextInLML;
+  if (AelNext)
+    AelNext->PrevInAEL = e->NextInLML;
+  e->NextInLML->Side = e->Side;
+  e->NextInLML->WindDelta = e->WindDelta;
+  e->NextInLML->WindCnt = e->WindCnt;
+  e->NextInLML->WindCnt2 = e->WindCnt2;
+  e = e->NextInLML;
+  e->Curr = e->Bot;
+  e->PrevInAEL = AelPrev;
+  e->NextInAEL = AelNext;
+  if (!IsHorizontal(*e))
+    InsertScanbeam(e->Top.Y);
+}
+//------------------------------------------------------------------------------
+
+bool ClipperBase::LocalMinimaPending() {
+  return (m_CurrentLM != m_MinimaList.end());
+}
+
+//------------------------------------------------------------------------------
+// TClipper methods ...
+//------------------------------------------------------------------------------
+
+Clipper::Clipper(int initOptions)
+    : ClipperBase() // constructor
+{
+  m_ExecuteLocked = false;
+  m_UseFullRange = false;
+  m_ReverseOutput = ((initOptions & ioReverseSolution) != 0);
+  m_StrictSimple = ((initOptions & ioStrictlySimple) != 0);
+  m_PreserveCollinear = ((initOptions & ioPreserveCollinear) != 0);
+  m_HasOpenPaths = false;
+#ifdef use_xyz
+  m_ZFill = 0;
+#endif
+}
+//------------------------------------------------------------------------------
+
+#ifdef use_xyz
+void Clipper::ZFillFunction(ZFillCallback zFillFunc) { m_ZFill = zFillFunc; }
+//------------------------------------------------------------------------------
+#endif
+
+bool Clipper::Execute(ClipType clipType, Paths &solution,
+                      PolyFillType fillType) {
+  return Execute(clipType, solution, fillType, fillType);
+}
+//------------------------------------------------------------------------------
+
+bool Clipper::Execute(ClipType clipType, PolyTree &polytree,
+                      PolyFillType fillType) {
+  return Execute(clipType, polytree, fillType, fillType);
+}
+//------------------------------------------------------------------------------
+
+bool Clipper::Execute(ClipType clipType, Paths &solution,
+                      PolyFillType subjFillType, PolyFillType clipFillType) {
+  if (m_ExecuteLocked)
+    return false;
+  if (m_HasOpenPaths)
+    throw clipperException(
+        "Error: PolyTree struct is needed for open path clipping.");
+  m_ExecuteLocked = true;
+  solution.resize(0);
+  m_SubjFillType = subjFillType;
+  m_ClipFillType = clipFillType;
+  m_ClipType = clipType;
+  m_UsingPolyTree = false;
+  bool succeeded = ExecuteInternal();
+  if (succeeded)
+    BuildResult(solution);
+  DisposeAllOutRecs();
+  m_ExecuteLocked = false;
+  return succeeded;
+}
+//------------------------------------------------------------------------------
+
+bool Clipper::Execute(ClipType clipType, PolyTree &polytree,
+                      PolyFillType subjFillType, PolyFillType clipFillType) {
+  if (m_ExecuteLocked)
+    return false;
+  m_ExecuteLocked = true;
+  m_SubjFillType = subjFillType;
+  m_ClipFillType = clipFillType;
+  m_ClipType = clipType;
+  m_UsingPolyTree = true;
+  bool succeeded = ExecuteInternal();
+  if (succeeded)
+    BuildResult2(polytree);
+  DisposeAllOutRecs();
+  m_ExecuteLocked = false;
+  return succeeded;
+}
+//------------------------------------------------------------------------------
+
+void Clipper::FixHoleLinkage(OutRec &outrec) {
+  // skip OutRecs that (a) contain outermost polygons or
+  //(b) already have the correct owner/child linkage ...
+  if (!outrec.FirstLeft ||
+      (outrec.IsHole != outrec.FirstLeft->IsHole && outrec.FirstLeft->Pts))
+    return;
+
+  OutRec *orfl = outrec.FirstLeft;
+  while (orfl && ((orfl->IsHole == outrec.IsHole) || !orfl->Pts))
+    orfl = orfl->FirstLeft;
+  outrec.FirstLeft = orfl;
+}
+//------------------------------------------------------------------------------
+
+bool Clipper::ExecuteInternal() {
+  bool succeeded = true;
+  try {
+    Reset();
+    m_Maxima = MaximaList();
+    m_SortedEdges = 0;
+
+    succeeded = true;
+    cInt botY, topY;
+    if (!PopScanbeam(botY))
+      return false;
+    InsertLocalMinimaIntoAEL(botY);
+    while (PopScanbeam(topY) || LocalMinimaPending()) {
+      ProcessHorizontals();
+      ClearGhostJoins();
+      if (!ProcessIntersections(topY)) {
+        succeeded = false;
+        break;
+      }
+      ProcessEdgesAtTopOfScanbeam(topY);
+      botY = topY;
+      InsertLocalMinimaIntoAEL(botY);
+    }
+  } catch (...) {
+    succeeded = false;
+  }
+
+  if (succeeded) {
+    // fix orientations ...
+    for (PolyOutList::size_type i = 0; i < m_PolyOuts.size(); ++i) {
+      OutRec *outRec = m_PolyOuts[i];
+      if (!outRec->Pts || outRec->IsOpen)
+        continue;
+      if ((outRec->IsHole ^ m_ReverseOutput) == (Area(*outRec) > 0))
+        ReversePolyPtLinks(outRec->Pts);
+    }
+
+    if (!m_Joins.empty())
+      JoinCommonEdges();
+
+    // unfortunately FixupOutPolygon() must be done after JoinCommonEdges()
+    for (PolyOutList::size_type i = 0; i < m_PolyOuts.size(); ++i) {
+      OutRec *outRec = m_PolyOuts[i];
+      if (!outRec->Pts)
+        continue;
+      if (outRec->IsOpen)
+        FixupOutPolyline(*outRec);
+      else
+        FixupOutPolygon(*outRec);
+    }
+
+    if (m_StrictSimple)
+      DoSimplePolygons();
+  }
+
+  ClearJoins();
+  ClearGhostJoins();
+  return succeeded;
+}
+//------------------------------------------------------------------------------
+
+void Clipper::SetWindingCount(TEdge &edge) {
+  TEdge *e = edge.PrevInAEL;
+  // find the edge of the same polytype that immediately preceeds 'edge' in AEL
+  while (e && ((e->PolyTyp != edge.PolyTyp) || (e->WindDelta == 0)))
+    e = e->PrevInAEL;
+  if (!e) {
+    if (edge.WindDelta == 0) {
+      PolyFillType pft =
+          (edge.PolyTyp == ptSubject ? m_SubjFillType : m_ClipFillType);
+      edge.WindCnt = (pft == pftNegative ? -1 : 1);
+    } else
+      edge.WindCnt = edge.WindDelta;
+    edge.WindCnt2 = 0;
+    e = m_ActiveEdges; // ie get ready to calc WindCnt2
+  } else if (edge.WindDelta == 0 && m_ClipType != ctUnion) {
+    edge.WindCnt = 1;
+    edge.WindCnt2 = e->WindCnt2;
+    e = e->NextInAEL; // ie get ready to calc WindCnt2
+  } else if (IsEvenOddFillType(edge)) {
+    // EvenOdd filling ...
+    if (edge.WindDelta == 0) {
+      // are we inside a subj polygon ...
+      bool Inside = true;
+      TEdge *e2 = e->PrevInAEL;
+      while (e2) {
+        if (e2->PolyTyp == e->PolyTyp && e2->WindDelta != 0)
+          Inside = !Inside;
+        e2 = e2->PrevInAEL;
+      }
+      edge.WindCnt = (Inside ? 0 : 1);
+    } else {
+      edge.WindCnt = edge.WindDelta;
+    }
+    edge.WindCnt2 = e->WindCnt2;
+    e = e->NextInAEL; // ie get ready to calc WindCnt2
+  } else {
+    // nonZero, Positive or Negative filling ...
+    if (e->WindCnt * e->WindDelta < 0) {
+      // prev edge is 'decreasing' WindCount (WC) toward zero
+      // so we're outside the previous polygon ...
+      if (Abs(e->WindCnt) > 1) {
+        // outside prev poly but still inside another.
+        // when reversing direction of prev poly use the same WC
+        if (e->WindDelta * edge.WindDelta < 0)
+          edge.WindCnt = e->WindCnt;
+        // otherwise continue to 'decrease' WC ...
+        else
+          edge.WindCnt = e->WindCnt + edge.WindDelta;
+      } else
+        // now outside all polys of same polytype so set own WC ...
+        edge.WindCnt = (edge.WindDelta == 0 ? 1 : edge.WindDelta);
+    } else {
+      // prev edge is 'increasing' WindCount (WC) away from zero
+      // so we're inside the previous polygon ...
+      if (edge.WindDelta == 0)
+        edge.WindCnt = (e->WindCnt < 0 ? e->WindCnt - 1 : e->WindCnt + 1);
+      // if wind direction is reversing prev then use same WC
+      else if (e->WindDelta * edge.WindDelta < 0)
+        edge.WindCnt = e->WindCnt;
+      // otherwise add to WC ...
+      else
+        edge.WindCnt = e->WindCnt + edge.WindDelta;
+    }
+    edge.WindCnt2 = e->WindCnt2;
+    e = e->NextInAEL; // ie get ready to calc WindCnt2
+  }
+
+  // update WindCnt2 ...
+  if (IsEvenOddAltFillType(edge)) {
+    // EvenOdd filling ...
+    while (e != &edge) {
+      if (e->WindDelta != 0)
+        edge.WindCnt2 = (edge.WindCnt2 == 0 ? 1 : 0);
+      e = e->NextInAEL;
+    }
+  } else {
+    // nonZero, Positive or Negative filling ...
+    while (e != &edge) {
+      edge.WindCnt2 += e->WindDelta;
+      e = e->NextInAEL;
+    }
+  }
+}
+//------------------------------------------------------------------------------
+
+bool Clipper::IsEvenOddFillType(const TEdge &edge) const {
+  if (edge.PolyTyp == ptSubject)
+    return m_SubjFillType == pftEvenOdd;
+  else
+    return m_ClipFillType == pftEvenOdd;
+}
+//------------------------------------------------------------------------------
+
+bool Clipper::IsEvenOddAltFillType(const TEdge &edge) const {
+  if (edge.PolyTyp == ptSubject)
+    return m_ClipFillType == pftEvenOdd;
+  else
+    return m_SubjFillType == pftEvenOdd;
+}
+//------------------------------------------------------------------------------
+
+bool Clipper::IsContributing(const TEdge &edge) const {
+  PolyFillType pft, pft2;
+  if (edge.PolyTyp == ptSubject) {
+    pft = m_SubjFillType;
+    pft2 = m_ClipFillType;
+  } else {
+    pft = m_ClipFillType;
+    pft2 = m_SubjFillType;
+  }
+
+  switch (pft) {
+  case pftEvenOdd:
+    // return false if a subj line has been flagged as inside a subj polygon
+    if (edge.WindDelta == 0 && edge.WindCnt != 1)
+      return false;
+    break;
+  case pftNonZero:
+    if (Abs(edge.WindCnt) != 1)
+      return false;
+    break;
+  case pftPositive:
+    if (edge.WindCnt != 1)
+      return false;
+    break;
+  default: // pftNegative
+    if (edge.WindCnt != -1)
+      return false;
+  }
+
+  switch (m_ClipType) {
+  case ctIntersection:
+    switch (pft2) {
+    case pftEvenOdd:
+    case pftNonZero:
+      return (edge.WindCnt2 != 0);
+    case pftPositive:
+      return (edge.WindCnt2 > 0);
+    default:
+      return (edge.WindCnt2 < 0);
+    }
+    break;
+  case ctUnion:
+    switch (pft2) {
+    case pftEvenOdd:
+    case pftNonZero:
+      return (edge.WindCnt2 == 0);
+    case pftPositive:
+      return (edge.WindCnt2 <= 0);
+    default:
+      return (edge.WindCnt2 >= 0);
+    }
+    break;
+  case ctDifference:
+    if (edge.PolyTyp == ptSubject)
+      switch (pft2) {
+      case pftEvenOdd:
+      case pftNonZero:
+        return (edge.WindCnt2 == 0);
+      case pftPositive:
+        return (edge.WindCnt2 <= 0);
+      default:
+        return (edge.WindCnt2 >= 0);
+      }
+    else
+      switch (pft2) {
+      case pftEvenOdd:
+      case pftNonZero:
+        return (edge.WindCnt2 != 0);
+      case pftPositive:
+        return (edge.WindCnt2 > 0);
+      default:
+        return (edge.WindCnt2 < 0);
+      }
+    break;
+  case ctXor:
+    if (edge.WindDelta == 0) // XOr always contributing unless open
+      switch (pft2) {
+      case pftEvenOdd:
+      case pftNonZero:
+        return (edge.WindCnt2 == 0);
+      case pftPositive:
+        return (edge.WindCnt2 <= 0);
+      default:
+        return (edge.WindCnt2 >= 0);
+      }
+    else
+      return true;
+    break;
+  default:
+    return true;
+  }
+}
+//------------------------------------------------------------------------------
+
+OutPt *Clipper::AddLocalMinPoly(TEdge *e1, TEdge *e2, const IntPoint &Pt) {
+  OutPt *result;
+  TEdge *e, *prevE;
+  if (IsHorizontal(*e2) || (e1->Dx > e2->Dx)) {
+    result = AddOutPt(e1, Pt);
+    e2->OutIdx = e1->OutIdx;
+    e1->Side = esLeft;
+    e2->Side = esRight;
+    e = e1;
+    if (e->PrevInAEL == e2)
+      prevE = e2->PrevInAEL;
+    else
+      prevE = e->PrevInAEL;
+  } else {
+    result = AddOutPt(e2, Pt);
+    e1->OutIdx = e2->OutIdx;
+    e1->Side = esRight;
+    e2->Side = esLeft;
+    e = e2;
+    if (e->PrevInAEL == e1)
+      prevE = e1->PrevInAEL;
+    else
+      prevE = e->PrevInAEL;
+  }
+
+  if (prevE && prevE->OutIdx >= 0 && prevE->Top.Y < Pt.Y && e->Top.Y < Pt.Y) {
+    cInt xPrev = TopX(*prevE, Pt.Y);
+    cInt xE = TopX(*e, Pt.Y);
+    if (xPrev == xE && (e->WindDelta != 0) && (prevE->WindDelta != 0) &&
+        SlopesEqual(IntPoint(xPrev, Pt.Y), prevE->Top, IntPoint(xE, Pt.Y),
+                    e->Top, m_UseFullRange)) {
+      OutPt *outPt = AddOutPt(prevE, Pt);
+      AddJoin(result, outPt, e->Top);
+    }
+  }
+  return result;
+}
+//------------------------------------------------------------------------------
+
+void Clipper::AddLocalMaxPoly(TEdge *e1, TEdge *e2, const IntPoint &Pt) {
+  AddOutPt(e1, Pt);
+  if (e2->WindDelta == 0)
+    AddOutPt(e2, Pt);
+  if (e1->OutIdx == e2->OutIdx) {
+    e1->OutIdx = Unassigned;
+    e2->OutIdx = Unassigned;
+  } else if (e1->OutIdx < e2->OutIdx)
+    AppendPolygon(e1, e2);
+  else
+    AppendPolygon(e2, e1);
+}
+//------------------------------------------------------------------------------
+
+void Clipper::AddEdgeToSEL(TEdge *edge) {
+  // SEL pointers in PEdge are reused to build a list of horizontal edges.
+  // However, we don't need to worry about order with horizontal edge
+  // processing.
+  if (!m_SortedEdges) {
+    m_SortedEdges = edge;
+    edge->PrevInSEL = 0;
+    edge->NextInSEL = 0;
+  } else {
+    edge->NextInSEL = m_SortedEdges;
+    edge->PrevInSEL = 0;
+    m_SortedEdges->PrevInSEL = edge;
+    m_SortedEdges = edge;
+  }
+}
+//------------------------------------------------------------------------------
+
+bool Clipper::PopEdgeFromSEL(TEdge *&edge) {
+  if (!m_SortedEdges)
+    return false;
+  edge = m_SortedEdges;
+  DeleteFromSEL(m_SortedEdges);
+  return true;
+}
+//------------------------------------------------------------------------------
+
+void Clipper::CopyAELToSEL() {
+  TEdge *e = m_ActiveEdges;
+  m_SortedEdges = e;
+  while (e) {
+    e->PrevInSEL = e->PrevInAEL;
+    e->NextInSEL = e->NextInAEL;
+    e = e->NextInAEL;
+  }
+}
+//------------------------------------------------------------------------------
+
+void Clipper::AddJoin(OutPt *op1, OutPt *op2, const IntPoint OffPt) {
+  Join *j = new Join;
+  j->OutPt1 = op1;
+  j->OutPt2 = op2;
+  j->OffPt = OffPt;
+  m_Joins.push_back(j);
+}
+//------------------------------------------------------------------------------
+
+void Clipper::ClearJoins() {
+  for (JoinList::size_type i = 0; i < m_Joins.size(); i++)
+    delete m_Joins[i];
+  m_Joins.resize(0);
+}
+//------------------------------------------------------------------------------
+
+void Clipper::ClearGhostJoins() {
+  for (JoinList::size_type i = 0; i < m_GhostJoins.size(); i++)
+    delete m_GhostJoins[i];
+  m_GhostJoins.resize(0);
+}
+//------------------------------------------------------------------------------
+
+void Clipper::AddGhostJoin(OutPt *op, const IntPoint OffPt) {
+  Join *j = new Join;
+  j->OutPt1 = op;
+  j->OutPt2 = 0;
+  j->OffPt = OffPt;
+  m_GhostJoins.push_back(j);
+}
+//------------------------------------------------------------------------------
+
+void Clipper::InsertLocalMinimaIntoAEL(const cInt botY) {
+  const LocalMinimum *lm;
+  while (PopLocalMinima(botY, lm)) {
+    TEdge *lb = lm->LeftBound;
+    TEdge *rb = lm->RightBound;
+
+    OutPt *Op1 = 0;
+    if (!lb) {
+      // nb: don't insert LB into either AEL or SEL
+      InsertEdgeIntoAEL(rb, 0);
+      SetWindingCount(*rb);
+      if (IsContributing(*rb))
+        Op1 = AddOutPt(rb, rb->Bot);
+    } else if (!rb) {
+      InsertEdgeIntoAEL(lb, 0);
+      SetWindingCount(*lb);
+      if (IsContributing(*lb))
+        Op1 = AddOutPt(lb, lb->Bot);
+      InsertScanbeam(lb->Top.Y);
+    } else {
+      InsertEdgeIntoAEL(lb, 0);
+      InsertEdgeIntoAEL(rb, lb);
+      SetWindingCount(*lb);
+      rb->WindCnt = lb->WindCnt;
+      rb->WindCnt2 = lb->WindCnt2;
+      if (IsContributing(*lb))
+        Op1 = AddLocalMinPoly(lb, rb, lb->Bot);
+      InsertScanbeam(lb->Top.Y);
+    }
+
+    if (rb) {
+      if (IsHorizontal(*rb)) {
+        AddEdgeToSEL(rb);
+        if (rb->NextInLML)
+          InsertScanbeam(rb->NextInLML->Top.Y);
+      } else
+        InsertScanbeam(rb->Top.Y);
+    }
+
+    if (!lb || !rb)
+      continue;
+
+    // if any output polygons share an edge, they'll need joining later ...
+    if (Op1 && IsHorizontal(*rb) && m_GhostJoins.size() > 0 &&
+        (rb->WindDelta != 0)) {
+      for (JoinList::size_type i = 0; i < m_GhostJoins.size(); ++i) {
+        Join *jr = m_GhostJoins[i];
+        // if the horizontal Rb and a 'ghost' horizontal overlap, then convert
+        // the 'ghost' join to a real join ready for later ...
+        if (HorzSegmentsOverlap(jr->OutPt1->Pt.X, jr->OffPt.X, rb->Bot.X,
+                                rb->Top.X))
+          AddJoin(jr->OutPt1, Op1, jr->OffPt);
+      }
+    }
+
+    if (lb->OutIdx >= 0 && lb->PrevInAEL &&
+        lb->PrevInAEL->Curr.X == lb->Bot.X && lb->PrevInAEL->OutIdx >= 0 &&
+        SlopesEqual(lb->PrevInAEL->Bot, lb->PrevInAEL->Top, lb->Curr, lb->Top,
+                    m_UseFullRange) &&
+        (lb->WindDelta != 0) && (lb->PrevInAEL->WindDelta != 0)) {
+      OutPt *Op2 = AddOutPt(lb->PrevInAEL, lb->Bot);
+      AddJoin(Op1, Op2, lb->Top);
+    }
+
+    if (lb->NextInAEL != rb) {
+
+      if (rb->OutIdx >= 0 && rb->PrevInAEL->OutIdx >= 0 &&
+          SlopesEqual(rb->PrevInAEL->Curr, rb->PrevInAEL->Top, rb->Curr,
+                      rb->Top, m_UseFullRange) &&
+          (rb->WindDelta != 0) && (rb->PrevInAEL->WindDelta != 0)) {
+        OutPt *Op2 = AddOutPt(rb->PrevInAEL, rb->Bot);
+        AddJoin(Op1, Op2, rb->Top);
+      }
+
+      TEdge *e = lb->NextInAEL;
+      if (e) {
+        while (e != rb) {
+          // nb: For calculating winding counts etc, IntersectEdges() assumes
+          // that param1 will be to the Right of param2 ABOVE the intersection
+          // ...
+          IntersectEdges(rb, e, lb->Curr); // order important here
+          e = e->NextInAEL;
+        }
+      }
+    }
+  }
+}
+//------------------------------------------------------------------------------
+
+void Clipper::DeleteFromSEL(TEdge *e) {
+  TEdge *SelPrev = e->PrevInSEL;
+  TEdge *SelNext = e->NextInSEL;
+  if (!SelPrev && !SelNext && (e != m_SortedEdges))
+    return; // already deleted
+  if (SelPrev)
+    SelPrev->NextInSEL = SelNext;
+  else
+    m_SortedEdges = SelNext;
+  if (SelNext)
+    SelNext->PrevInSEL = SelPrev;
+  e->NextInSEL = 0;
+  e->PrevInSEL = 0;
+}
+//------------------------------------------------------------------------------
+
+#ifdef use_xyz
+void Clipper::SetZ(IntPoint &pt, TEdge &e1, TEdge &e2) {
+  if (pt.Z != 0 || !m_ZFill)
+    return;
+  else if (pt == e1.Bot)
+    pt.Z = e1.Bot.Z;
+  else if (pt == e1.Top)
+    pt.Z = e1.Top.Z;
+  else if (pt == e2.Bot)
+    pt.Z = e2.Bot.Z;
+  else if (pt == e2.Top)
+    pt.Z = e2.Top.Z;
+  else
+    (*m_ZFill)(e1.Bot, e1.Top, e2.Bot, e2.Top, pt);
+}
+//------------------------------------------------------------------------------
+#endif
+
+void Clipper::IntersectEdges(TEdge *e1, TEdge *e2, IntPoint &Pt) {
+  bool e1Contributing = (e1->OutIdx >= 0);
+  bool e2Contributing = (e2->OutIdx >= 0);
+
+#ifdef use_xyz
+  SetZ(Pt, *e1, *e2);
+#endif
+
+#ifdef use_lines
+  // if either edge is on an OPEN path ...
+  if (e1->WindDelta == 0 || e2->WindDelta == 0) {
+    // ignore subject-subject open path intersections UNLESS they
+    // are both open paths, AND they are both 'contributing maximas' ...
+    if (e1->WindDelta == 0 && e2->WindDelta == 0)
+      return;
+
+    // if intersecting a subj line with a subj poly ...
+    else if (e1->PolyTyp == e2->PolyTyp && e1->WindDelta != e2->WindDelta &&
+             m_ClipType == ctUnion) {
+      if (e1->WindDelta == 0) {
+        if (e2Contributing) {
+          AddOutPt(e1, Pt);
+          if (e1Contributing)
+            e1->OutIdx = Unassigned;
+        }
+      } else {
+        if (e1Contributing) {
+          AddOutPt(e2, Pt);
+          if (e2Contributing)
+            e2->OutIdx = Unassigned;
+        }
+      }
+    } else if (e1->PolyTyp != e2->PolyTyp) {
+      // toggle subj open path OutIdx on/off when Abs(clip.WndCnt) == 1 ...
+      if ((e1->WindDelta == 0) && abs(e2->WindCnt) == 1 &&
+          (m_ClipType != ctUnion || e2->WindCnt2 == 0)) {
+        AddOutPt(e1, Pt);
+        if (e1Contributing)
+          e1->OutIdx = Unassigned;
+      } else if ((e2->WindDelta == 0) && (abs(e1->WindCnt) == 1) &&
+                 (m_ClipType != ctUnion || e1->WindCnt2 == 0)) {
+        AddOutPt(e2, Pt);
+        if (e2Contributing)
+          e2->OutIdx = Unassigned;
+      }
+    }
+    return;
+  }
+#endif
+
+  // update winding counts...
+  // assumes that e1 will be to the Right of e2 ABOVE the intersection
+  if (e1->PolyTyp == e2->PolyTyp) {
+    if (IsEvenOddFillType(*e1)) {
+      int oldE1WindCnt = e1->WindCnt;
+      e1->WindCnt = e2->WindCnt;
+      e2->WindCnt = oldE1WindCnt;
+    } else {
+      if (e1->WindCnt + e2->WindDelta == 0)
+        e1->WindCnt = -e1->WindCnt;
+      else
+        e1->WindCnt += e2->WindDelta;
+      if (e2->WindCnt - e1->WindDelta == 0)
+        e2->WindCnt = -e2->WindCnt;
+      else
+        e2->WindCnt -= e1->WindDelta;
+    }
+  } else {
+    if (!IsEvenOddFillType(*e2))
+      e1->WindCnt2 += e2->WindDelta;
+    else
+      e1->WindCnt2 = (e1->WindCnt2 == 0) ? 1 : 0;
+    if (!IsEvenOddFillType(*e1))
+      e2->WindCnt2 -= e1->WindDelta;
+    else
+      e2->WindCnt2 = (e2->WindCnt2 == 0) ? 1 : 0;
+  }
+
+  PolyFillType e1FillType, e2FillType, e1FillType2, e2FillType2;
+  if (e1->PolyTyp == ptSubject) {
+    e1FillType = m_SubjFillType;
+    e1FillType2 = m_ClipFillType;
+  } else {
+    e1FillType = m_ClipFillType;
+    e1FillType2 = m_SubjFillType;
+  }
+  if (e2->PolyTyp == ptSubject) {
+    e2FillType = m_SubjFillType;
+    e2FillType2 = m_ClipFillType;
+  } else {
+    e2FillType = m_ClipFillType;
+    e2FillType2 = m_SubjFillType;
+  }
+
+  cInt e1Wc, e2Wc;
+  switch (e1FillType) {
+  case pftPositive:
+    e1Wc = e1->WindCnt;
+    break;
+  case pftNegative:
+    e1Wc = -e1->WindCnt;
+    break;
+  default:
+    e1Wc = Abs(e1->WindCnt);
+  }
+  switch (e2FillType) {
+  case pftPositive:
+    e2Wc = e2->WindCnt;
+    break;
+  case pftNegative:
+    e2Wc = -e2->WindCnt;
+    break;
+  default:
+    e2Wc = Abs(e2->WindCnt);
+  }
+
+  if (e1Contributing && e2Contributing) {
+    if ((e1Wc != 0 && e1Wc != 1) || (e2Wc != 0 && e2Wc != 1) ||
+        (e1->PolyTyp != e2->PolyTyp && m_ClipType != ctXor)) {
+      AddLocalMaxPoly(e1, e2, Pt);
+    } else {
+      AddOutPt(e1, Pt);
+      AddOutPt(e2, Pt);
+      SwapSides(*e1, *e2);
+      SwapPolyIndexes(*e1, *e2);
+    }
+  } else if (e1Contributing) {
+    if (e2Wc == 0 || e2Wc == 1) {
+      AddOutPt(e1, Pt);
+      SwapSides(*e1, *e2);
+      SwapPolyIndexes(*e1, *e2);
+    }
+  } else if (e2Contributing) {
+    if (e1Wc == 0 || e1Wc == 1) {
+      AddOutPt(e2, Pt);
+      SwapSides(*e1, *e2);
+      SwapPolyIndexes(*e1, *e2);
+    }
+  } else if ((e1Wc == 0 || e1Wc == 1) && (e2Wc == 0 || e2Wc == 1)) {
+    // neither edge is currently contributing ...
+
+    cInt e1Wc2, e2Wc2;
+    switch (e1FillType2) {
+    case pftPositive:
+      e1Wc2 = e1->WindCnt2;
+      break;
+    case pftNegative:
+      e1Wc2 = -e1->WindCnt2;
+      break;
+    default:
+      e1Wc2 = Abs(e1->WindCnt2);
+    }
+    switch (e2FillType2) {
+    case pftPositive:
+      e2Wc2 = e2->WindCnt2;
+      break;
+    case pftNegative:
+      e2Wc2 = -e2->WindCnt2;
+      break;
+    default:
+      e2Wc2 = Abs(e2->WindCnt2);
+    }
+
+    if (e1->PolyTyp != e2->PolyTyp) {
+      AddLocalMinPoly(e1, e2, Pt);
+    } else if (e1Wc == 1 && e2Wc == 1)
+      switch (m_ClipType) {
+      case ctIntersection:
+        if (e1Wc2 > 0 && e2Wc2 > 0)
+          AddLocalMinPoly(e1, e2, Pt);
+        break;
+      case ctUnion:
+        if (e1Wc2 <= 0 && e2Wc2 <= 0)
+          AddLocalMinPoly(e1, e2, Pt);
+        break;
+      case ctDifference:
+        if (((e1->PolyTyp == ptClip) && (e1Wc2 > 0) && (e2Wc2 > 0)) ||
+            ((e1->PolyTyp == ptSubject) && (e1Wc2 <= 0) && (e2Wc2 <= 0)))
+          AddLocalMinPoly(e1, e2, Pt);
+        break;
+      case ctXor:
+        AddLocalMinPoly(e1, e2, Pt);
+      }
+    else
+      SwapSides(*e1, *e2);
+  }
+}
+//------------------------------------------------------------------------------
+
+void Clipper::SetHoleState(TEdge *e, OutRec *outrec) {
+  TEdge *e2 = e->PrevInAEL;
+  TEdge *eTmp = 0;
+  while (e2) {
+    if (e2->OutIdx >= 0 && e2->WindDelta != 0) {
+      if (!eTmp)
+        eTmp = e2;
+      else if (eTmp->OutIdx == e2->OutIdx)
+        eTmp = 0;
+    }
+    e2 = e2->PrevInAEL;
+  }
+  if (!eTmp) {
+    outrec->FirstLeft = 0;
+    outrec->IsHole = false;
+  } else {
+    outrec->FirstLeft = m_PolyOuts[eTmp->OutIdx];
+    outrec->IsHole = !outrec->FirstLeft->IsHole;
+  }
+}
+//------------------------------------------------------------------------------
+
+OutRec *GetLowermostRec(OutRec *outRec1, OutRec *outRec2) {
+  // work out which polygon fragment has the correct hole state ...
+  if (!outRec1->BottomPt)
+    outRec1->BottomPt = GetBottomPt(outRec1->Pts);
+  if (!outRec2->BottomPt)
+    outRec2->BottomPt = GetBottomPt(outRec2->Pts);
+  OutPt *OutPt1 = outRec1->BottomPt;
+  OutPt *OutPt2 = outRec2->BottomPt;
+  if (OutPt1->Pt.Y > OutPt2->Pt.Y)
+    return outRec1;
+  else if (OutPt1->Pt.Y < OutPt2->Pt.Y)
+    return outRec2;
+  else if (OutPt1->Pt.X < OutPt2->Pt.X)
+    return outRec1;
+  else if (OutPt1->Pt.X > OutPt2->Pt.X)
+    return outRec2;
+  else if (OutPt1->Next == OutPt1)
+    return outRec2;
+  else if (OutPt2->Next == OutPt2)
+    return outRec1;
+  else if (FirstIsBottomPt(OutPt1, OutPt2))
+    return outRec1;
+  else
+    return outRec2;
+}
+//------------------------------------------------------------------------------
+
+bool OutRec1RightOfOutRec2(OutRec *outRec1, OutRec *outRec2) {
+  do {
+    outRec1 = outRec1->FirstLeft;
+    if (outRec1 == outRec2)
+      return true;
+  } while (outRec1);
+  return false;
+}
+//------------------------------------------------------------------------------
+
+OutRec *Clipper::GetOutRec(int Idx) {
+  OutRec *outrec = m_PolyOuts[Idx];
+  while (outrec != m_PolyOuts[outrec->Idx])
+    outrec = m_PolyOuts[outrec->Idx];
+  return outrec;
+}
+//------------------------------------------------------------------------------
+
+void Clipper::AppendPolygon(TEdge *e1, TEdge *e2) {
+  // get the start and ends of both output polygons ...
+  OutRec *outRec1 = m_PolyOuts[e1->OutIdx];
+  OutRec *outRec2 = m_PolyOuts[e2->OutIdx];
+
+  OutRec *holeStateRec;
+  if (OutRec1RightOfOutRec2(outRec1, outRec2))
+    holeStateRec = outRec2;
+  else if (OutRec1RightOfOutRec2(outRec2, outRec1))
+    holeStateRec = outRec1;
+  else
+    holeStateRec = GetLowermostRec(outRec1, outRec2);
+
+  // get the start and ends of both output polygons and
+  // join e2 poly onto e1 poly and delete pointers to e2 ...
+
+  OutPt *p1_lft = outRec1->Pts;
+  OutPt *p1_rt = p1_lft->Prev;
+  OutPt *p2_lft = outRec2->Pts;
+  OutPt *p2_rt = p2_lft->Prev;
+
+  // join e2 poly onto e1 poly and delete pointers to e2 ...
+  if (e1->Side == esLeft) {
+    if (e2->Side == esLeft) {
+      // z y x a b c
+      ReversePolyPtLinks(p2_lft);
+      p2_lft->Next = p1_lft;
+      p1_lft->Prev = p2_lft;
+      p1_rt->Next = p2_rt;
+      p2_rt->Prev = p1_rt;
+      outRec1->Pts = p2_rt;
+    } else {
+      // x y z a b c
+      p2_rt->Next = p1_lft;
+      p1_lft->Prev = p2_rt;
+      p2_lft->Prev = p1_rt;
+      p1_rt->Next = p2_lft;
+      outRec1->Pts = p2_lft;
+    }
+  } else {
+    if (e2->Side == esRight) {
+      // a b c z y x
+      ReversePolyPtLinks(p2_lft);
+      p1_rt->Next = p2_rt;
+      p2_rt->Prev = p1_rt;
+      p2_lft->Next = p1_lft;
+      p1_lft->Prev = p2_lft;
+    } else {
+      // a b c x y z
+      p1_rt->Next = p2_lft;
+      p2_lft->Prev = p1_rt;
+      p1_lft->Prev = p2_rt;
+      p2_rt->Next = p1_lft;
+    }
+  }
+
+  outRec1->BottomPt = 0;
+  if (holeStateRec == outRec2) {
+    if (outRec2->FirstLeft != outRec1)
+      outRec1->FirstLeft = outRec2->FirstLeft;
+    outRec1->IsHole = outRec2->IsHole;
+  }
+  outRec2->Pts = 0;
+  outRec2->BottomPt = 0;
+  outRec2->FirstLeft = outRec1;
+
+  int OKIdx = e1->OutIdx;
+  int ObsoleteIdx = e2->OutIdx;
+
+  e1->OutIdx =
+      Unassigned; // nb: safe because we only get here via AddLocalMaxPoly
+  e2->OutIdx = Unassigned;
+
+  TEdge *e = m_ActiveEdges;
+  while (e) {
+    if (e->OutIdx == ObsoleteIdx) {
+      e->OutIdx = OKIdx;
+      e->Side = e1->Side;
+      break;
+    }
+    e = e->NextInAEL;
+  }
+
+  outRec2->Idx = outRec1->Idx;
+}
+//------------------------------------------------------------------------------
+
+OutPt *Clipper::AddOutPt(TEdge *e, const IntPoint &pt) {
+  if (e->OutIdx < 0) {
+    OutRec *outRec = CreateOutRec();
+    outRec->IsOpen = (e->WindDelta == 0);
+    OutPt *newOp = new OutPt;
+    outRec->Pts = newOp;
+    newOp->Idx = outRec->Idx;
+    newOp->Pt = pt;
+    newOp->Next = newOp;
+    newOp->Prev = newOp;
+    if (!outRec->IsOpen)
+      SetHoleState(e, outRec);
+    e->OutIdx = outRec->Idx;
+    return newOp;
+  } else {
+    OutRec *outRec = m_PolyOuts[e->OutIdx];
+    // OutRec.Pts is the 'Left-most' point & OutRec.Pts.Prev is the 'Right-most'
+    OutPt *op = outRec->Pts;
+
+    bool ToFront = (e->Side == esLeft);
+    if (ToFront && (pt == op->Pt))
+      return op;
+    else if (!ToFront && (pt == op->Prev->Pt))
+      return op->Prev;
+
+    OutPt *newOp = new OutPt;
+    newOp->Idx = outRec->Idx;
+    newOp->Pt = pt;
+    newOp->Next = op;
+    newOp->Prev = op->Prev;
+    newOp->Prev->Next = newOp;
+    op->Prev = newOp;
+    if (ToFront)
+      outRec->Pts = newOp;
+    return newOp;
+  }
+}
+//------------------------------------------------------------------------------
+
+OutPt *Clipper::GetLastOutPt(TEdge *e) {
+  OutRec *outRec = m_PolyOuts[e->OutIdx];
+  if (e->Side == esLeft)
+    return outRec->Pts;
+  else
+    return outRec->Pts->Prev;
+}
+//------------------------------------------------------------------------------
+
+void Clipper::ProcessHorizontals() {
+  TEdge *horzEdge;
+  while (PopEdgeFromSEL(horzEdge))
+    ProcessHorizontal(horzEdge);
+}
+//------------------------------------------------------------------------------
+
+inline bool IsMinima(TEdge *e) {
+  return e && (e->Prev->NextInLML != e) && (e->Next->NextInLML != e);
+}
+//------------------------------------------------------------------------------
+
+inline bool IsMaxima(TEdge *e, const cInt Y) {
+  return e && e->Top.Y == Y && !e->NextInLML;
+}
+//------------------------------------------------------------------------------
+
+inline bool IsIntermediate(TEdge *e, const cInt Y) {
+  return e->Top.Y == Y && e->NextInLML;
+}
+//------------------------------------------------------------------------------
+
+TEdge *GetMaximaPair(TEdge *e) {
+  if ((e->Next->Top == e->Top) && !e->Next->NextInLML)
+    return e->Next;
+  else if ((e->Prev->Top == e->Top) && !e->Prev->NextInLML)
+    return e->Prev;
+  else
+    return 0;
+}
+//------------------------------------------------------------------------------
+
+TEdge *GetMaximaPairEx(TEdge *e) {
+  // as GetMaximaPair() but returns 0 if MaxPair isn't in AEL (unless it's
+  // horizontal)
+  TEdge *result = GetMaximaPair(e);
+  if (result &&
+      (result->OutIdx == Skip ||
+       (result->NextInAEL == result->PrevInAEL && !IsHorizontal(*result))))
+    return 0;
+  return result;
+}
+//------------------------------------------------------------------------------
+
+void Clipper::SwapPositionsInSEL(TEdge *Edge1, TEdge *Edge2) {
+  if (!(Edge1->NextInSEL) && !(Edge1->PrevInSEL))
+    return;
+  if (!(Edge2->NextInSEL) && !(Edge2->PrevInSEL))
+    return;
+
+  if (Edge1->NextInSEL == Edge2) {
+    TEdge *Next = Edge2->NextInSEL;
+    if (Next)
+      Next->PrevInSEL = Edge1;
+    TEdge *Prev = Edge1->PrevInSEL;
+    if (Prev)
+      Prev->NextInSEL = Edge2;
+    Edge2->PrevInSEL = Prev;
+    Edge2->NextInSEL = Edge1;
+    Edge1->PrevInSEL = Edge2;
+    Edge1->NextInSEL = Next;
+  } else if (Edge2->NextInSEL == Edge1) {
+    TEdge *Next = Edge1->NextInSEL;
+    if (Next)
+      Next->PrevInSEL = Edge2;
+    TEdge *Prev = Edge2->PrevInSEL;
+    if (Prev)
+      Prev->NextInSEL = Edge1;
+    Edge1->PrevInSEL = Prev;
+    Edge1->NextInSEL = Edge2;
+    Edge2->PrevInSEL = Edge1;
+    Edge2->NextInSEL = Next;
+  } else {
+    TEdge *Next = Edge1->NextInSEL;
+    TEdge *Prev = Edge1->PrevInSEL;
+    Edge1->NextInSEL = Edge2->NextInSEL;
+    if (Edge1->NextInSEL)
+      Edge1->NextInSEL->PrevInSEL = Edge1;
+    Edge1->PrevInSEL = Edge2->PrevInSEL;
+    if (Edge1->PrevInSEL)
+      Edge1->PrevInSEL->NextInSEL = Edge1;
+    Edge2->NextInSEL = Next;
+    if (Edge2->NextInSEL)
+      Edge2->NextInSEL->PrevInSEL = Edge2;
+    Edge2->PrevInSEL = Prev;
+    if (Edge2->PrevInSEL)
+      Edge2->PrevInSEL->NextInSEL = Edge2;
+  }
+
+  if (!Edge1->PrevInSEL)
+    m_SortedEdges = Edge1;
+  else if (!Edge2->PrevInSEL)
+    m_SortedEdges = Edge2;
+}
+//------------------------------------------------------------------------------
+
+TEdge *GetNextInAEL(TEdge *e, Direction dir) {
+  return dir == dLeftToRight ? e->NextInAEL : e->PrevInAEL;
+}
+//------------------------------------------------------------------------------
+
+void GetHorzDirection(TEdge &HorzEdge, Direction &Dir, cInt &Left,
+                      cInt &Right) {
+  if (HorzEdge.Bot.X < HorzEdge.Top.X) {
+    Left = HorzEdge.Bot.X;
+    Right = HorzEdge.Top.X;
+    Dir = dLeftToRight;
+  } else {
+    Left = HorzEdge.Top.X;
+    Right = HorzEdge.Bot.X;
+    Dir = dRightToLeft;
+  }
+}
+//------------------------------------------------------------------------
+
+/*******************************************************************************
+* Notes: Horizontal edges (HEs) at scanline intersections (ie at the Top or    *
+* Bottom of a scanbeam) are processed as if layered. The order in which HEs    *
+* are processed doesn't matter. HEs intersect with other HE Bot.Xs only [#]    *
+* (or they could intersect with Top.Xs only, ie EITHER Bot.Xs OR Top.Xs),      *
+* and with other non-horizontal edges [*]. Once these intersections are        *
+* processed, intermediate HEs then 'promote' the Edge above (NextInLML) into   *
+* the AEL. These 'promoted' edges may in turn intersect [%] with other HEs.    *
+*******************************************************************************/
+
+void Clipper::ProcessHorizontal(TEdge *horzEdge) {
+  Direction dir;
+  cInt horzLeft, horzRight;
+  bool IsOpen = (horzEdge->WindDelta == 0);
+
+  GetHorzDirection(*horzEdge, dir, horzLeft, horzRight);
+
+  TEdge *eLastHorz = horzEdge, *eMaxPair = 0;
+  while (eLastHorz->NextInLML && IsHorizontal(*eLastHorz->NextInLML))
+    eLastHorz = eLastHorz->NextInLML;
+  if (!eLastHorz->NextInLML)
+    eMaxPair = GetMaximaPair(eLastHorz);
+
+  MaximaList::const_iterator maxIt;
+  MaximaList::const_reverse_iterator maxRit;
+  if (m_Maxima.size() > 0) {
+    // get the first maxima in range (X) ...
+    if (dir == dLeftToRight) {
+      maxIt = m_Maxima.begin();
+      while (maxIt != m_Maxima.end() && *maxIt <= horzEdge->Bot.X)
+        maxIt++;
+      if (maxIt != m_Maxima.end() && *maxIt >= eLastHorz->Top.X)
+        maxIt = m_Maxima.end();
+    } else {
+      maxRit = m_Maxima.rbegin();
+      while (maxRit != m_Maxima.rend() && *maxRit > horzEdge->Bot.X)
+        maxRit++;
+      if (maxRit != m_Maxima.rend() && *maxRit <= eLastHorz->Top.X)
+        maxRit = m_Maxima.rend();
+    }
+  }
+
+  OutPt *op1 = 0;
+
+  for (;;) // loop through consec. horizontal edges
+  {
+
+    bool IsLastHorz = (horzEdge == eLastHorz);
+    TEdge *e = GetNextInAEL(horzEdge, dir);
+    while (e) {
+
+      // this code block inserts extra coords into horizontal edges (in output
+      // polygons) whereever maxima touch these horizontal edges. This helps
+      //'simplifying' polygons (ie if the Simplify property is set).
+      if (m_Maxima.size() > 0) {
+        if (dir == dLeftToRight) {
+          while (maxIt != m_Maxima.end() && *maxIt < e->Curr.X) {
+            if (horzEdge->OutIdx >= 0 && !IsOpen)
+              AddOutPt(horzEdge, IntPoint(*maxIt, horzEdge->Bot.Y));
+            maxIt++;
+          }
+        } else {
+          while (maxRit != m_Maxima.rend() && *maxRit > e->Curr.X) {
+            if (horzEdge->OutIdx >= 0 && !IsOpen)
+              AddOutPt(horzEdge, IntPoint(*maxRit, horzEdge->Bot.Y));
+            maxRit++;
+          }
+        }
+      };
+
+      if ((dir == dLeftToRight && e->Curr.X > horzRight) ||
+          (dir == dRightToLeft && e->Curr.X < horzLeft))
+        break;
+
+      // Also break if we've got to the end of an intermediate horizontal edge
+      // ...
+      // nb: Smaller Dx's are to the right of larger Dx's ABOVE the horizontal.
+      if (e->Curr.X == horzEdge->Top.X && horzEdge->NextInLML &&
+          e->Dx < horzEdge->NextInLML->Dx)
+        break;
+
+      if (horzEdge->OutIdx >= 0 && !IsOpen) // note: may be done multiple times
+      {
+#ifdef use_xyz
+        if (dir == dLeftToRight)
+          SetZ(e->Curr, *horzEdge, *e);
+        else
+          SetZ(e->Curr, *e, *horzEdge);
+#endif
+        op1 = AddOutPt(horzEdge, e->Curr);
+        TEdge *eNextHorz = m_SortedEdges;
+        while (eNextHorz) {
+          if (eNextHorz->OutIdx >= 0 &&
+              HorzSegmentsOverlap(horzEdge->Bot.X, horzEdge->Top.X,
+                                  eNextHorz->Bot.X, eNextHorz->Top.X)) {
+            OutPt *op2 = GetLastOutPt(eNextHorz);
+            AddJoin(op2, op1, eNextHorz->Top);
+          }
+          eNextHorz = eNextHorz->NextInSEL;
+        }
+        AddGhostJoin(op1, horzEdge->Bot);
+      }
+
+      // OK, so far we're still in range of the horizontal Edge  but make sure
+      // we're at the last of consec. horizontals when matching with eMaxPair
+      if (e == eMaxPair && IsLastHorz) {
+        if (horzEdge->OutIdx >= 0)
+          AddLocalMaxPoly(horzEdge, eMaxPair, horzEdge->Top);
+        DeleteFromAEL(horzEdge);
+        DeleteFromAEL(eMaxPair);
+        return;
+      }
+
+      if (dir == dLeftToRight) {
+        IntPoint Pt = IntPoint(e->Curr.X, horzEdge->Curr.Y);
+        IntersectEdges(horzEdge, e, Pt);
+      } else {
+        IntPoint Pt = IntPoint(e->Curr.X, horzEdge->Curr.Y);
+        IntersectEdges(e, horzEdge, Pt);
+      }
+      TEdge *eNext = GetNextInAEL(e, dir);
+      SwapPositionsInAEL(horzEdge, e);
+      e = eNext;
+    } // end while(e)
+
+    // Break out of loop if HorzEdge.NextInLML is not also horizontal ...
+    if (!horzEdge->NextInLML || !IsHorizontal(*horzEdge->NextInLML))
+      break;
+
+    UpdateEdgeIntoAEL(horzEdge);
+    if (horzEdge->OutIdx >= 0)
+      AddOutPt(horzEdge, horzEdge->Bot);
+    GetHorzDirection(*horzEdge, dir, horzLeft, horzRight);
+
+  } // end for (;;)
+
+  if (horzEdge->OutIdx >= 0 && !op1) {
+    op1 = GetLastOutPt(horzEdge);
+    TEdge *eNextHorz = m_SortedEdges;
+    while (eNextHorz) {
+      if (eNextHorz->OutIdx >= 0 &&
+          HorzSegmentsOverlap(horzEdge->Bot.X, horzEdge->Top.X,
+                              eNextHorz->Bot.X, eNextHorz->Top.X)) {
+        OutPt *op2 = GetLastOutPt(eNextHorz);
+        AddJoin(op2, op1, eNextHorz->Top);
+      }
+      eNextHorz = eNextHorz->NextInSEL;
+    }
+    AddGhostJoin(op1, horzEdge->Top);
+  }
+
+  if (horzEdge->NextInLML) {
+    if (horzEdge->OutIdx >= 0) {
+      op1 = AddOutPt(horzEdge, horzEdge->Top);
+      UpdateEdgeIntoAEL(horzEdge);
+      if (horzEdge->WindDelta == 0)
+        return;
+      // nb: HorzEdge is no longer horizontal here
+      TEdge *ePrev = horzEdge->PrevInAEL;
+      TEdge *eNext = horzEdge->NextInAEL;
+      if (ePrev && ePrev->Curr.X == horzEdge->Bot.X &&
+          ePrev->Curr.Y == horzEdge->Bot.Y && ePrev->WindDelta != 0 &&
+          (ePrev->OutIdx >= 0 && ePrev->Curr.Y > ePrev->Top.Y &&
+           SlopesEqual(*horzEdge, *ePrev, m_UseFullRange))) {
+        OutPt *op2 = AddOutPt(ePrev, horzEdge->Bot);
+        AddJoin(op1, op2, horzEdge->Top);
+      } else if (eNext && eNext->Curr.X == horzEdge->Bot.X &&
+                 eNext->Curr.Y == horzEdge->Bot.Y && eNext->WindDelta != 0 &&
+                 eNext->OutIdx >= 0 && eNext->Curr.Y > eNext->Top.Y &&
+                 SlopesEqual(*horzEdge, *eNext, m_UseFullRange)) {
+        OutPt *op2 = AddOutPt(eNext, horzEdge->Bot);
+        AddJoin(op1, op2, horzEdge->Top);
+      }
+    } else
+      UpdateEdgeIntoAEL(horzEdge);
+  } else {
+    if (horzEdge->OutIdx >= 0)
+      AddOutPt(horzEdge, horzEdge->Top);
+    DeleteFromAEL(horzEdge);
+  }
+}
+//------------------------------------------------------------------------------
+
+bool Clipper::ProcessIntersections(const cInt topY) {
+  if (!m_ActiveEdges)
+    return true;
+  try {
+    BuildIntersectList(topY);
+    size_t IlSize = m_IntersectList.size();
+    if (IlSize == 0)
+      return true;
+    if (IlSize == 1 || FixupIntersectionOrder())
+      ProcessIntersectList();
+    else
+      return false;
+  } catch (...) {
+    m_SortedEdges = 0;
+    DisposeIntersectNodes();
+    throw clipperException("ProcessIntersections error");
+  }
+  m_SortedEdges = 0;
+  return true;
+}
+//------------------------------------------------------------------------------
+
+void Clipper::DisposeIntersectNodes() {
+  for (size_t i = 0; i < m_IntersectList.size(); ++i)
+    delete m_IntersectList[i];
+  m_IntersectList.clear();
+}
+//------------------------------------------------------------------------------
+
+void Clipper::BuildIntersectList(const cInt topY) {
+  if (!m_ActiveEdges)
+    return;
+
+  // prepare for sorting ...
+  TEdge *e = m_ActiveEdges;
+  m_SortedEdges = e;
+  while (e) {
+    e->PrevInSEL = e->PrevInAEL;
+    e->NextInSEL = e->NextInAEL;
+    e->Curr.X = TopX(*e, topY);
+    e = e->NextInAEL;
+  }
+
+  // bubblesort ...
+  bool isModified;
+  do {
+    isModified = false;
+    e = m_SortedEdges;
+    while (e->NextInSEL) {
+      TEdge *eNext = e->NextInSEL;
+      IntPoint Pt;
+      if (e->Curr.X > eNext->Curr.X) {
+        IntersectPoint(*e, *eNext, Pt);
+        if (Pt.Y < topY)
+          Pt = IntPoint(TopX(*e, topY), topY);
+        IntersectNode *newNode = new IntersectNode;
+        newNode->Edge1 = e;
+        newNode->Edge2 = eNext;
+        newNode->Pt = Pt;
+        m_IntersectList.push_back(newNode);
+
+        SwapPositionsInSEL(e, eNext);
+        isModified = true;
+      } else
+        e = eNext;
+    }
+    if (e->PrevInSEL)
+      e->PrevInSEL->NextInSEL = 0;
+    else
+      break;
+  } while (isModified);
+  m_SortedEdges = 0; // important
+}
+//------------------------------------------------------------------------------
+
+void Clipper::ProcessIntersectList() {
+  for (size_t i = 0; i < m_IntersectList.size(); ++i) {
+    IntersectNode *iNode = m_IntersectList[i];
+    {
+      IntersectEdges(iNode->Edge1, iNode->Edge2, iNode->Pt);
+      SwapPositionsInAEL(iNode->Edge1, iNode->Edge2);
+    }
+    delete iNode;
+  }
+  m_IntersectList.clear();
+}
+//------------------------------------------------------------------------------
+
+bool IntersectListSort(IntersectNode *node1, IntersectNode *node2) {
+  return node2->Pt.Y < node1->Pt.Y;
+}
+//------------------------------------------------------------------------------
+
+inline bool EdgesAdjacent(const IntersectNode &inode) {
+  return (inode.Edge1->NextInSEL == inode.Edge2) ||
+         (inode.Edge1->PrevInSEL == inode.Edge2);
+}
+//------------------------------------------------------------------------------
+
+bool Clipper::FixupIntersectionOrder() {
+  // pre-condition: intersections are sorted Bottom-most first.
+  // Now it's crucial that intersections are made only between adjacent edges,
+  // so to ensure this the order of intersections may need adjusting ...
+  CopyAELToSEL();
+  std::sort(m_IntersectList.begin(), m_IntersectList.end(), IntersectListSort);
+  size_t cnt = m_IntersectList.size();
+  for (size_t i = 0; i < cnt; ++i) {
+    if (!EdgesAdjacent(*m_IntersectList[i])) {
+      size_t j = i + 1;
+      while (j < cnt && !EdgesAdjacent(*m_IntersectList[j]))
+        j++;
+      if (j == cnt)
+        return false;
+      std::swap(m_IntersectList[i], m_IntersectList[j]);
+    }
+    SwapPositionsInSEL(m_IntersectList[i]->Edge1, m_IntersectList[i]->Edge2);
+  }
+  return true;
+}
+//------------------------------------------------------------------------------
+
+void Clipper::DoMaxima(TEdge *e) {
+  TEdge *eMaxPair = GetMaximaPairEx(e);
+  if (!eMaxPair) {
+    if (e->OutIdx >= 0)
+      AddOutPt(e, e->Top);
+    DeleteFromAEL(e);
+    return;
+  }
+
+  TEdge *eNext = e->NextInAEL;
+  while (eNext && eNext != eMaxPair) {
+    IntersectEdges(e, eNext, e->Top);
+    SwapPositionsInAEL(e, eNext);
+    eNext = e->NextInAEL;
+  }
+
+  if (e->OutIdx == Unassigned && eMaxPair->OutIdx == Unassigned) {
+    DeleteFromAEL(e);
+    DeleteFromAEL(eMaxPair);
+  } else if (e->OutIdx >= 0 && eMaxPair->OutIdx >= 0) {
+    if (e->OutIdx >= 0)
+      AddLocalMaxPoly(e, eMaxPair, e->Top);
+    DeleteFromAEL(e);
+    DeleteFromAEL(eMaxPair);
+  }
+#ifdef use_lines
+  else if (e->WindDelta == 0) {
+    if (e->OutIdx >= 0) {
+      AddOutPt(e, e->Top);
+      e->OutIdx = Unassigned;
+    }
+    DeleteFromAEL(e);
+
+    if (eMaxPair->OutIdx >= 0) {
+      AddOutPt(eMaxPair, e->Top);
+      eMaxPair->OutIdx = Unassigned;
+    }
+    DeleteFromAEL(eMaxPair);
+  }
+#endif
+  else
+    throw clipperException("DoMaxima error");
+}
+//------------------------------------------------------------------------------
+
+void Clipper::ProcessEdgesAtTopOfScanbeam(const cInt topY) {
+  TEdge *e = m_ActiveEdges;
+  while (e) {
+    // 1. process maxima, treating them as if they're 'bent' horizontal edges,
+    //   but exclude maxima with horizontal edges. nb: e can't be a horizontal.
+    bool IsMaximaEdge = IsMaxima(e, topY);
+
+    if (IsMaximaEdge) {
+      TEdge *eMaxPair = GetMaximaPairEx(e);
+      IsMaximaEdge = (!eMaxPair || !IsHorizontal(*eMaxPair));
+    }
+
+    if (IsMaximaEdge) {
+      if (m_StrictSimple)
+        m_Maxima.push_back(e->Top.X);
+      TEdge *ePrev = e->PrevInAEL;
+      DoMaxima(e);
+      if (!ePrev)
+        e = m_ActiveEdges;
+      else
+        e = ePrev->NextInAEL;
+    } else {
+      // 2. promote horizontal edges, otherwise update Curr.X and Curr.Y ...
+      if (IsIntermediate(e, topY) && IsHorizontal(*e->NextInLML)) {
+        UpdateEdgeIntoAEL(e);
+        if (e->OutIdx >= 0)
+          AddOutPt(e, e->Bot);
+        AddEdgeToSEL(e);
+      } else {
+        e->Curr.X = TopX(*e, topY);
+        e->Curr.Y = topY;
+#ifdef use_xyz
+        e->Curr.Z =
+            topY == e->Top.Y ? e->Top.Z : (topY == e->Bot.Y ? e->Bot.Z : 0);
+#endif
+      }
+
+      // When StrictlySimple and 'e' is being touched by another edge, then
+      // make sure both edges have a vertex here ...
+      if (m_StrictSimple) {
+        TEdge *ePrev = e->PrevInAEL;
+        if ((e->OutIdx >= 0) && (e->WindDelta != 0) && ePrev &&
+            (ePrev->OutIdx >= 0) && (ePrev->Curr.X == e->Curr.X) &&
+            (ePrev->WindDelta != 0)) {
+          IntPoint pt = e->Curr;
+#ifdef use_xyz
+          SetZ(pt, *ePrev, *e);
+#endif
+          OutPt *op = AddOutPt(ePrev, pt);
+          OutPt *op2 = AddOutPt(e, pt);
+          AddJoin(op, op2, pt); // StrictlySimple (type-3) join
+        }
+      }
+
+      e = e->NextInAEL;
+    }
+  }
+
+  // 3. Process horizontals at the Top of the scanbeam ...
+  m_Maxima.sort();
+  ProcessHorizontals();
+  m_Maxima.clear();
+
+  // 4. Promote intermediate vertices ...
+  e = m_ActiveEdges;
+  while (e) {
+    if (IsIntermediate(e, topY)) {
+      OutPt *op = 0;
+      if (e->OutIdx >= 0)
+        op = AddOutPt(e, e->Top);
+      UpdateEdgeIntoAEL(e);
+
+      // if output polygons share an edge, they'll need joining later ...
+      TEdge *ePrev = e->PrevInAEL;
+      TEdge *eNext = e->NextInAEL;
+      if (ePrev && ePrev->Curr.X == e->Bot.X && ePrev->Curr.Y == e->Bot.Y &&
+          op && ePrev->OutIdx >= 0 && ePrev->Curr.Y > ePrev->Top.Y &&
+          SlopesEqual(e->Curr, e->Top, ePrev->Curr, ePrev->Top,
+                      m_UseFullRange) &&
+          (e->WindDelta != 0) && (ePrev->WindDelta != 0)) {
+        OutPt *op2 = AddOutPt(ePrev, e->Bot);
+        AddJoin(op, op2, e->Top);
+      } else if (eNext && eNext->Curr.X == e->Bot.X &&
+                 eNext->Curr.Y == e->Bot.Y && op && eNext->OutIdx >= 0 &&
+                 eNext->Curr.Y > eNext->Top.Y &&
+                 SlopesEqual(e->Curr, e->Top, eNext->Curr, eNext->Top,
+                             m_UseFullRange) &&
+                 (e->WindDelta != 0) && (eNext->WindDelta != 0)) {
+        OutPt *op2 = AddOutPt(eNext, e->Bot);
+        AddJoin(op, op2, e->Top);
+      }
+    }
+    e = e->NextInAEL;
+  }
+}
+//------------------------------------------------------------------------------
+
+void Clipper::FixupOutPolyline(OutRec &outrec) {
+  OutPt *pp = outrec.Pts;
+  OutPt *lastPP = pp->Prev;
+  while (pp != lastPP) {
+    pp = pp->Next;
+    if (pp->Pt == pp->Prev->Pt) {
+      if (pp == lastPP)
+        lastPP = pp->Prev;
+      OutPt *tmpPP = pp->Prev;
+      tmpPP->Next = pp->Next;
+      pp->Next->Prev = tmpPP;
+      delete pp;
+      pp = tmpPP;
+    }
+  }
+
+  if (pp == pp->Prev) {
+    DisposeOutPts(pp);
+    outrec.Pts = 0;
+    return;
+  }
+}
+//------------------------------------------------------------------------------
+
+void Clipper::FixupOutPolygon(OutRec &outrec) {
+  // FixupOutPolygon() - removes duplicate points and simplifies consecutive
+  // parallel edges by removing the middle vertex.
+  OutPt *lastOK = 0;
+  outrec.BottomPt = 0;
+  OutPt *pp = outrec.Pts;
+  bool preserveCol = m_PreserveCollinear || m_StrictSimple;
+
+  for (;;) {
+    if (pp->Prev == pp || pp->Prev == pp->Next) {
+      DisposeOutPts(pp);
+      outrec.Pts = 0;
+      return;
+    }
+
+    // test for duplicate points and collinear edges ...
+    if ((pp->Pt == pp->Next->Pt) || (pp->Pt == pp->Prev->Pt) ||
+        (SlopesEqual(pp->Prev->Pt, pp->Pt, pp->Next->Pt, m_UseFullRange) &&
+         (!preserveCol ||
+          !Pt2IsBetweenPt1AndPt3(pp->Prev->Pt, pp->Pt, pp->Next->Pt)))) {
+      lastOK = 0;
+      OutPt *tmp = pp;
+      pp->Prev->Next = pp->Next;
+      pp->Next->Prev = pp->Prev;
+      pp = pp->Prev;
+      delete tmp;
+    } else if (pp == lastOK)
+      break;
+    else {
+      if (!lastOK)
+        lastOK = pp;
+      pp = pp->Next;
+    }
+  }
+  outrec.Pts = pp;
+}
+//------------------------------------------------------------------------------
+
+int PointCount(OutPt *Pts) {
+  if (!Pts)
+    return 0;
+  int result = 0;
+  OutPt *p = Pts;
+  do {
+    result++;
+    p = p->Next;
+  } while (p != Pts);
+  return result;
+}
+//------------------------------------------------------------------------------
+
+void Clipper::BuildResult(Paths &polys) {
+  polys.reserve(m_PolyOuts.size());
+  for (PolyOutList::size_type i = 0; i < m_PolyOuts.size(); ++i) {
+    if (!m_PolyOuts[i]->Pts)
+      continue;
+    Path pg;
+    OutPt *p = m_PolyOuts[i]->Pts->Prev;
+    int cnt = PointCount(p);
+    if (cnt < 2)
+      continue;
+    pg.reserve(cnt);
+    for (int i = 0; i < cnt; ++i) {
+      pg.push_back(p->Pt);
+      p = p->Prev;
+    }
+    polys.push_back(pg);
+  }
+}
+//------------------------------------------------------------------------------
+
+void Clipper::BuildResult2(PolyTree &polytree) {
+  polytree.Clear();
+  polytree.AllNodes.reserve(m_PolyOuts.size());
+  // add each output polygon/contour to polytree ...
+  for (PolyOutList::size_type i = 0; i < m_PolyOuts.size(); i++) {
+    OutRec *outRec = m_PolyOuts[i];
+    int cnt = PointCount(outRec->Pts);
+    if ((outRec->IsOpen && cnt < 2) || (!outRec->IsOpen && cnt < 3))
+      continue;
+    FixHoleLinkage(*outRec);
+    PolyNode *pn = new PolyNode();
+    // nb: polytree takes ownership of all the PolyNodes
+    polytree.AllNodes.push_back(pn);
+    outRec->PolyNd = pn;
+    pn->Parent = 0;
+    pn->Index = 0;
+    pn->Contour.reserve(cnt);
+    OutPt *op = outRec->Pts->Prev;
+    for (int j = 0; j < cnt; j++) {
+      pn->Contour.push_back(op->Pt);
+      op = op->Prev;
+    }
+  }
+
+  // fixup PolyNode links etc ...
+  polytree.Childs.reserve(m_PolyOuts.size());
+  for (PolyOutList::size_type i = 0; i < m_PolyOuts.size(); i++) {
+    OutRec *outRec = m_PolyOuts[i];
+    if (!outRec->PolyNd)
+      continue;
+    if (outRec->IsOpen) {
+      outRec->PolyNd->m_IsOpen = true;
+      polytree.AddChild(*outRec->PolyNd);
+    } else if (outRec->FirstLeft && outRec->FirstLeft->PolyNd)
+      outRec->FirstLeft->PolyNd->AddChild(*outRec->PolyNd);
+    else
+      polytree.AddChild(*outRec->PolyNd);
+  }
+}
+//------------------------------------------------------------------------------
+
+void SwapIntersectNodes(IntersectNode &int1, IntersectNode &int2) {
+  // just swap the contents (because fIntersectNodes is a single-linked-list)
+  IntersectNode inode = int1; // gets a copy of Int1
+  int1.Edge1 = int2.Edge1;
+  int1.Edge2 = int2.Edge2;
+  int1.Pt = int2.Pt;
+  int2.Edge1 = inode.Edge1;
+  int2.Edge2 = inode.Edge2;
+  int2.Pt = inode.Pt;
+}
+//------------------------------------------------------------------------------
+
+inline bool E2InsertsBeforeE1(TEdge &e1, TEdge &e2) {
+  if (e2.Curr.X == e1.Curr.X) {
+    if (e2.Top.Y > e1.Top.Y)
+      return e2.Top.X < TopX(e1, e2.Top.Y);
+    else
+      return e1.Top.X > TopX(e2, e1.Top.Y);
+  } else
+    return e2.Curr.X < e1.Curr.X;
+}
+//------------------------------------------------------------------------------
+
+bool GetOverlap(const cInt a1, const cInt a2, const cInt b1, const cInt b2,
+                cInt &Left, cInt &Right) {
+  if (a1 < a2) {
+    if (b1 < b2) {
+      Left = std::max(a1, b1);
+      Right = std::min(a2, b2);
+    } else {
+      Left = std::max(a1, b2);
+      Right = std::min(a2, b1);
+    }
+  } else {
+    if (b1 < b2) {
+      Left = std::max(a2, b1);
+      Right = std::min(a1, b2);
+    } else {
+      Left = std::max(a2, b2);
+      Right = std::min(a1, b1);
+    }
+  }
+  return Left < Right;
+}
+//------------------------------------------------------------------------------
+
+inline void UpdateOutPtIdxs(OutRec &outrec) {
+  OutPt *op = outrec.Pts;
+  do {
+    op->Idx = outrec.Idx;
+    op = op->Prev;
+  } while (op != outrec.Pts);
+}
+//------------------------------------------------------------------------------
+
+void Clipper::InsertEdgeIntoAEL(TEdge *edge, TEdge *startEdge) {
+  if (!m_ActiveEdges) {
+    edge->PrevInAEL = 0;
+    edge->NextInAEL = 0;
+    m_ActiveEdges = edge;
+  } else if (!startEdge && E2InsertsBeforeE1(*m_ActiveEdges, *edge)) {
+    edge->PrevInAEL = 0;
+    edge->NextInAEL = m_ActiveEdges;
+    m_ActiveEdges->PrevInAEL = edge;
+    m_ActiveEdges = edge;
+  } else {
+    if (!startEdge)
+      startEdge = m_ActiveEdges;
+    while (startEdge->NextInAEL &&
+           !E2InsertsBeforeE1(*startEdge->NextInAEL, *edge))
+      startEdge = startEdge->NextInAEL;
+    edge->NextInAEL = startEdge->NextInAEL;
+    if (startEdge->NextInAEL)
+      startEdge->NextInAEL->PrevInAEL = edge;
+    edge->PrevInAEL = startEdge;
+    startEdge->NextInAEL = edge;
+  }
+}
+//----------------------------------------------------------------------
+
+OutPt *DupOutPt(OutPt *outPt, bool InsertAfter) {
+  OutPt *result = new OutPt;
+  result->Pt = outPt->Pt;
+  result->Idx = outPt->Idx;
+  if (InsertAfter) {
+    result->Next = outPt->Next;
+    result->Prev = outPt;
+    outPt->Next->Prev = result;
+    outPt->Next = result;
+  } else {
+    result->Prev = outPt->Prev;
+    result->Next = outPt;
+    outPt->Prev->Next = result;
+    outPt->Prev = result;
+  }
+  return result;
+}
+//------------------------------------------------------------------------------
+
+bool JoinHorz(OutPt *op1, OutPt *op1b, OutPt *op2, OutPt *op2b,
+              const IntPoint Pt, bool DiscardLeft) {
+  Direction Dir1 = (op1->Pt.X > op1b->Pt.X ? dRightToLeft : dLeftToRight);
+  Direction Dir2 = (op2->Pt.X > op2b->Pt.X ? dRightToLeft : dLeftToRight);
+  if (Dir1 == Dir2)
+    return false;
+
+  // When DiscardLeft, we want Op1b to be on the Left of Op1, otherwise we
+  // want Op1b to be on the Right. (And likewise with Op2 and Op2b.)
+  // So, to facilitate this while inserting Op1b and Op2b ...
+  // when DiscardLeft, make sure we're AT or RIGHT of Pt before adding Op1b,
+  // otherwise make sure we're AT or LEFT of Pt. (Likewise with Op2b.)
+  if (Dir1 == dLeftToRight) {
+    while (op1->Next->Pt.X <= Pt.X && op1->Next->Pt.X >= op1->Pt.X &&
+           op1->Next->Pt.Y == Pt.Y)
+      op1 = op1->Next;
+    if (DiscardLeft && (op1->Pt.X != Pt.X))
+      op1 = op1->Next;
+    op1b = DupOutPt(op1, !DiscardLeft);
+    if (op1b->Pt != Pt) {
+      op1 = op1b;
+      op1->Pt = Pt;
+      op1b = DupOutPt(op1, !DiscardLeft);
+    }
+  } else {
+    while (op1->Next->Pt.X >= Pt.X && op1->Next->Pt.X <= op1->Pt.X &&
+           op1->Next->Pt.Y == Pt.Y)
+      op1 = op1->Next;
+    if (!DiscardLeft && (op1->Pt.X != Pt.X))
+      op1 = op1->Next;
+    op1b = DupOutPt(op1, DiscardLeft);
+    if (op1b->Pt != Pt) {
+      op1 = op1b;
+      op1->Pt = Pt;
+      op1b = DupOutPt(op1, DiscardLeft);
+    }
+  }
+
+  if (Dir2 == dLeftToRight) {
+    while (op2->Next->Pt.X <= Pt.X && op2->Next->Pt.X >= op2->Pt.X &&
+           op2->Next->Pt.Y == Pt.Y)
+      op2 = op2->Next;
+    if (DiscardLeft && (op2->Pt.X != Pt.X))
+      op2 = op2->Next;
+    op2b = DupOutPt(op2, !DiscardLeft);
+    if (op2b->Pt != Pt) {
+      op2 = op2b;
+      op2->Pt = Pt;
+      op2b = DupOutPt(op2, !DiscardLeft);
+    };
+  } else {
+    while (op2->Next->Pt.X >= Pt.X && op2->Next->Pt.X <= op2->Pt.X &&
+           op2->Next->Pt.Y == Pt.Y)
+      op2 = op2->Next;
+    if (!DiscardLeft && (op2->Pt.X != Pt.X))
+      op2 = op2->Next;
+    op2b = DupOutPt(op2, DiscardLeft);
+    if (op2b->Pt != Pt) {
+      op2 = op2b;
+      op2->Pt = Pt;
+      op2b = DupOutPt(op2, DiscardLeft);
+    };
+  };
+
+  if ((Dir1 == dLeftToRight) == DiscardLeft) {
+    op1->Prev = op2;
+    op2->Next = op1;
+    op1b->Next = op2b;
+    op2b->Prev = op1b;
+  } else {
+    op1->Next = op2;
+    op2->Prev = op1;
+    op1b->Prev = op2b;
+    op2b->Next = op1b;
+  }
+  return true;
+}
+//------------------------------------------------------------------------------
+
+bool Clipper::JoinPoints(Join *j, OutRec *outRec1, OutRec *outRec2) {
+  OutPt *op1 = j->OutPt1, *op1b;
+  OutPt *op2 = j->OutPt2, *op2b;
+
+  // There are 3 kinds of joins for output polygons ...
+  // 1. Horizontal joins where Join.OutPt1 & Join.OutPt2 are vertices anywhere
+  // along (horizontal) collinear edges (& Join.OffPt is on the same
+  // horizontal).
+  // 2. Non-horizontal joins where Join.OutPt1 & Join.OutPt2 are at the same
+  // location at the Bottom of the overlapping segment (& Join.OffPt is above).
+  // 3. StrictSimple joins where edges touch but are not collinear and where
+  // Join.OutPt1, Join.OutPt2 & Join.OffPt all share the same point.
+  bool isHorizontal = (j->OutPt1->Pt.Y == j->OffPt.Y);
+
+  if (isHorizontal && (j->OffPt == j->OutPt1->Pt) &&
+      (j->OffPt == j->OutPt2->Pt)) {
+    // Strictly Simple join ...
+    if (outRec1 != outRec2)
+      return false;
+    op1b = j->OutPt1->Next;
+    while (op1b != op1 && (op1b->Pt == j->OffPt))
+      op1b = op1b->Next;
+    bool reverse1 = (op1b->Pt.Y > j->OffPt.Y);
+    op2b = j->OutPt2->Next;
+    while (op2b != op2 && (op2b->Pt == j->OffPt))
+      op2b = op2b->Next;
+    bool reverse2 = (op2b->Pt.Y > j->OffPt.Y);
+    if (reverse1 == reverse2)
+      return false;
+    if (reverse1) {
+      op1b = DupOutPt(op1, false);
+      op2b = DupOutPt(op2, true);
+      op1->Prev = op2;
+      op2->Next = op1;
+      op1b->Next = op2b;
+      op2b->Prev = op1b;
+      j->OutPt1 = op1;
+      j->OutPt2 = op1b;
+      return true;
+    } else {
+      op1b = DupOutPt(op1, true);
+      op2b = DupOutPt(op2, false);
+      op1->Next = op2;
+      op2->Prev = op1;
+      op1b->Prev = op2b;
+      op2b->Next = op1b;
+      j->OutPt1 = op1;
+      j->OutPt2 = op1b;
+      return true;
+    }
+  } else if (isHorizontal) {
+    // treat horizontal joins differently to non-horizontal joins since with
+    // them we're not yet sure where the overlapping is. OutPt1.Pt & OutPt2.Pt
+    // may be anywhere along the horizontal edge.
+    op1b = op1;
+    while (op1->Prev->Pt.Y == op1->Pt.Y && op1->Prev != op1b &&
+           op1->Prev != op2)
+      op1 = op1->Prev;
+    while (op1b->Next->Pt.Y == op1b->Pt.Y && op1b->Next != op1 &&
+           op1b->Next != op2)
+      op1b = op1b->Next;
+    if (op1b->Next == op1 || op1b->Next == op2)
+      return false; // a flat 'polygon'
+
+    op2b = op2;
+    while (op2->Prev->Pt.Y == op2->Pt.Y && op2->Prev != op2b &&
+           op2->Prev != op1b)
+      op2 = op2->Prev;
+    while (op2b->Next->Pt.Y == op2b->Pt.Y && op2b->Next != op2 &&
+           op2b->Next != op1)
+      op2b = op2b->Next;
+    if (op2b->Next == op2 || op2b->Next == op1)
+      return false; // a flat 'polygon'
+
+    cInt Left, Right;
+    // Op1 --> Op1b & Op2 --> Op2b are the extremites of the horizontal edges
+    if (!GetOverlap(op1->Pt.X, op1b->Pt.X, op2->Pt.X, op2b->Pt.X, Left, Right))
+      return false;
+
+    // DiscardLeftSide: when overlapping edges are joined, a spike will created
+    // which needs to be cleaned up. However, we don't want Op1 or Op2 caught up
+    // on the discard Side as either may still be needed for other joins ...
+    IntPoint Pt;
+    bool DiscardLeftSide;
+    if (op1->Pt.X >= Left && op1->Pt.X <= Right) {
+      Pt = op1->Pt;
+      DiscardLeftSide = (op1->Pt.X > op1b->Pt.X);
+    } else if (op2->Pt.X >= Left && op2->Pt.X <= Right) {
+      Pt = op2->Pt;
+      DiscardLeftSide = (op2->Pt.X > op2b->Pt.X);
+    } else if (op1b->Pt.X >= Left && op1b->Pt.X <= Right) {
+      Pt = op1b->Pt;
+      DiscardLeftSide = op1b->Pt.X > op1->Pt.X;
+    } else {
+      Pt = op2b->Pt;
+      DiscardLeftSide = (op2b->Pt.X > op2->Pt.X);
+    }
+    j->OutPt1 = op1;
+    j->OutPt2 = op2;
+    return JoinHorz(op1, op1b, op2, op2b, Pt, DiscardLeftSide);
+  } else {
+    // nb: For non-horizontal joins ...
+    //    1. Jr.OutPt1.Pt.Y == Jr.OutPt2.Pt.Y
+    //    2. Jr.OutPt1.Pt > Jr.OffPt.Y
+
+    // make sure the polygons are correctly oriented ...
+    op1b = op1->Next;
+    while ((op1b->Pt == op1->Pt) && (op1b != op1))
+      op1b = op1b->Next;
+    bool Reverse1 = ((op1b->Pt.Y > op1->Pt.Y) ||
+                     !SlopesEqual(op1->Pt, op1b->Pt, j->OffPt, m_UseFullRange));
+    if (Reverse1) {
+      op1b = op1->Prev;
+      while ((op1b->Pt == op1->Pt) && (op1b != op1))
+        op1b = op1b->Prev;
+      if ((op1b->Pt.Y > op1->Pt.Y) ||
+          !SlopesEqual(op1->Pt, op1b->Pt, j->OffPt, m_UseFullRange))
+        return false;
+    };
+    op2b = op2->Next;
+    while ((op2b->Pt == op2->Pt) && (op2b != op2))
+      op2b = op2b->Next;
+    bool Reverse2 = ((op2b->Pt.Y > op2->Pt.Y) ||
+                     !SlopesEqual(op2->Pt, op2b->Pt, j->OffPt, m_UseFullRange));
+    if (Reverse2) {
+      op2b = op2->Prev;
+      while ((op2b->Pt == op2->Pt) && (op2b != op2))
+        op2b = op2b->Prev;
+      if ((op2b->Pt.Y > op2->Pt.Y) ||
+          !SlopesEqual(op2->Pt, op2b->Pt, j->OffPt, m_UseFullRange))
+        return false;
+    }
+
+    if ((op1b == op1) || (op2b == op2) || (op1b == op2b) ||
+        ((outRec1 == outRec2) && (Reverse1 == Reverse2)))
+      return false;
+
+    if (Reverse1) {
+      op1b = DupOutPt(op1, false);
+      op2b = DupOutPt(op2, true);
+      op1->Prev = op2;
+      op2->Next = op1;
+      op1b->Next = op2b;
+      op2b->Prev = op1b;
+      j->OutPt1 = op1;
+      j->OutPt2 = op1b;
+      return true;
+    } else {
+      op1b = DupOutPt(op1, true);
+      op2b = DupOutPt(op2, false);
+      op1->Next = op2;
+      op2->Prev = op1;
+      op1b->Prev = op2b;
+      op2b->Next = op1b;
+      j->OutPt1 = op1;
+      j->OutPt2 = op1b;
+      return true;
+    }
+  }
+}
+//----------------------------------------------------------------------
+
+static OutRec *ParseFirstLeft(OutRec *FirstLeft) {
+  while (FirstLeft && !FirstLeft->Pts)
+    FirstLeft = FirstLeft->FirstLeft;
+  return FirstLeft;
+}
+//------------------------------------------------------------------------------
+
+void Clipper::FixupFirstLefts1(OutRec *OldOutRec, OutRec *NewOutRec) {
+  // tests if NewOutRec contains the polygon before reassigning FirstLeft
+  for (PolyOutList::size_type i = 0; i < m_PolyOuts.size(); ++i) {
+    OutRec *outRec = m_PolyOuts[i];
+    OutRec *firstLeft = ParseFirstLeft(outRec->FirstLeft);
+    if (outRec->Pts && firstLeft == OldOutRec) {
+      if (Poly2ContainsPoly1(outRec->Pts, NewOutRec->Pts))
+        outRec->FirstLeft = NewOutRec;
+    }
+  }
+}
+//----------------------------------------------------------------------
+
+void Clipper::FixupFirstLefts2(OutRec *InnerOutRec, OutRec *OuterOutRec) {
+  // A polygon has split into two such that one is now the inner of the other.
+  // It's possible that these polygons now wrap around other polygons, so check
+  // every polygon that's also contained by OuterOutRec's FirstLeft container
+  //(including 0) to see if they've become inner to the new inner polygon ...
+  OutRec *orfl = OuterOutRec->FirstLeft;
+  for (PolyOutList::size_type i = 0; i < m_PolyOuts.size(); ++i) {
+    OutRec *outRec = m_PolyOuts[i];
+
+    if (!outRec->Pts || outRec == OuterOutRec || outRec == InnerOutRec)
+      continue;
+    OutRec *firstLeft = ParseFirstLeft(outRec->FirstLeft);
+    if (firstLeft != orfl && firstLeft != InnerOutRec &&
+        firstLeft != OuterOutRec)
+      continue;
+    if (Poly2ContainsPoly1(outRec->Pts, InnerOutRec->Pts))
+      outRec->FirstLeft = InnerOutRec;
+    else if (Poly2ContainsPoly1(outRec->Pts, OuterOutRec->Pts))
+      outRec->FirstLeft = OuterOutRec;
+    else if (outRec->FirstLeft == InnerOutRec ||
+             outRec->FirstLeft == OuterOutRec)
+      outRec->FirstLeft = orfl;
+  }
+}
+//----------------------------------------------------------------------
+void Clipper::FixupFirstLefts3(OutRec *OldOutRec, OutRec *NewOutRec) {
+  // reassigns FirstLeft WITHOUT testing if NewOutRec contains the polygon
+  for (PolyOutList::size_type i = 0; i < m_PolyOuts.size(); ++i) {
+    OutRec *outRec = m_PolyOuts[i];
+    OutRec *firstLeft = ParseFirstLeft(outRec->FirstLeft);
+    if (outRec->Pts && firstLeft == OldOutRec)
+      outRec->FirstLeft = NewOutRec;
+  }
+}
+//----------------------------------------------------------------------
+
+void Clipper::JoinCommonEdges() {
+  for (JoinList::size_type i = 0; i < m_Joins.size(); i++) {
+    Join *join = m_Joins[i];
+
+    OutRec *outRec1 = GetOutRec(join->OutPt1->Idx);
+    OutRec *outRec2 = GetOutRec(join->OutPt2->Idx);
+
+    if (!outRec1->Pts || !outRec2->Pts)
+      continue;
+    if (outRec1->IsOpen || outRec2->IsOpen)
+      continue;
+
+    // get the polygon fragment with the correct hole state (FirstLeft)
+    // before calling JoinPoints() ...
+    OutRec *holeStateRec;
+    if (outRec1 == outRec2)
+      holeStateRec = outRec1;
+    else if (OutRec1RightOfOutRec2(outRec1, outRec2))
+      holeStateRec = outRec2;
+    else if (OutRec1RightOfOutRec2(outRec2, outRec1))
+      holeStateRec = outRec1;
+    else
+      holeStateRec = GetLowermostRec(outRec1, outRec2);
+
+    if (!JoinPoints(join, outRec1, outRec2))
+      continue;
+
+    if (outRec1 == outRec2) {
+      // instead of joining two polygons, we've just created a new one by
+      // splitting one polygon into two.
+      outRec1->Pts = join->OutPt1;
+      outRec1->BottomPt = 0;
+      outRec2 = CreateOutRec();
+      outRec2->Pts = join->OutPt2;
+
+      // update all OutRec2.Pts Idx's ...
+      UpdateOutPtIdxs(*outRec2);
+
+      if (Poly2ContainsPoly1(outRec2->Pts, outRec1->Pts)) {
+        // outRec1 contains outRec2 ...
+        outRec2->IsHole = !outRec1->IsHole;
+        outRec2->FirstLeft = outRec1;
+
+        if (m_UsingPolyTree)
+          FixupFirstLefts2(outRec2, outRec1);
+
+        if ((outRec2->IsHole ^ m_ReverseOutput) == (Area(*outRec2) > 0))
+          ReversePolyPtLinks(outRec2->Pts);
+
+      } else if (Poly2ContainsPoly1(outRec1->Pts, outRec2->Pts)) {
+        // outRec2 contains outRec1 ...
+        outRec2->IsHole = outRec1->IsHole;
+        outRec1->IsHole = !outRec2->IsHole;
+        outRec2->FirstLeft = outRec1->FirstLeft;
+        outRec1->FirstLeft = outRec2;
+
+        if (m_UsingPolyTree)
+          FixupFirstLefts2(outRec1, outRec2);
+
+        if ((outRec1->IsHole ^ m_ReverseOutput) == (Area(*outRec1) > 0))
+          ReversePolyPtLinks(outRec1->Pts);
+      } else {
+        // the 2 polygons are completely separate ...
+        outRec2->IsHole = outRec1->IsHole;
+        outRec2->FirstLeft = outRec1->FirstLeft;
+
+        // fixup FirstLeft pointers that may need reassigning to OutRec2
+        if (m_UsingPolyTree)
+          FixupFirstLefts1(outRec1, outRec2);
+      }
+
+    } else {
+      // joined 2 polygons together ...
+
+      outRec2->Pts = 0;
+      outRec2->BottomPt = 0;
+      outRec2->Idx = outRec1->Idx;
+
+      outRec1->IsHole = holeStateRec->IsHole;
+      if (holeStateRec == outRec2)
+        outRec1->FirstLeft = outRec2->FirstLeft;
+      outRec2->FirstLeft = outRec1;
+
+      if (m_UsingPolyTree)
+        FixupFirstLefts3(outRec2, outRec1);
+    }
+  }
+}
+
+//------------------------------------------------------------------------------
+// ClipperOffset support functions ...
+//------------------------------------------------------------------------------
+
+DoublePoint GetUnitNormal(const IntPoint &pt1, const IntPoint &pt2) {
+  if (pt2.X == pt1.X && pt2.Y == pt1.Y)
+    return DoublePoint(0, 0);
+
+  double Dx = (double)(pt2.X - pt1.X);
+  double dy = (double)(pt2.Y - pt1.Y);
+  double f = 1 * 1.0 / std::sqrt(Dx * Dx + dy * dy);
+  Dx *= f;
+  dy *= f;
+  return DoublePoint(dy, -Dx);
+}
+
+//------------------------------------------------------------------------------
+// ClipperOffset class
+//------------------------------------------------------------------------------
+
+ClipperOffset::ClipperOffset(double miterLimit, double arcTolerance) {
+  this->MiterLimit = miterLimit;
+  this->ArcTolerance = arcTolerance;
+  m_lowest.X = -1;
+}
+//------------------------------------------------------------------------------
+
+ClipperOffset::~ClipperOffset() { Clear(); }
+//------------------------------------------------------------------------------
+
+void ClipperOffset::Clear() {
+  for (int i = 0; i < m_polyNodes.ChildCount(); ++i)
+    delete m_polyNodes.Childs[i];
+  m_polyNodes.Childs.clear();
+  m_lowest.X = -1;
+}
+//------------------------------------------------------------------------------
+
+void ClipperOffset::AddPath(const Path &path, JoinType joinType,
+                            EndType endType) {
+  int highI = (int)path.size() - 1;
+  if (highI < 0)
+    return;
+  PolyNode *newNode = new PolyNode();
+  newNode->m_jointype = joinType;
+  newNode->m_endtype = endType;
+
+  // strip duplicate points from path and also get index to the lowest point ...
+  if (endType == etClosedLine || endType == etClosedPolygon)
+    while (highI > 0 && path[0] == path[highI])
+      highI--;
+  newNode->Contour.reserve(highI + 1);
+  newNode->Contour.push_back(path[0]);
+  int j = 0, k = 0;
+  for (int i = 1; i <= highI; i++)
+    if (newNode->Contour[j] != path[i]) {
+      j++;
+      newNode->Contour.push_back(path[i]);
+      if (path[i].Y > newNode->Contour[k].Y ||
+          (path[i].Y == newNode->Contour[k].Y &&
+           path[i].X < newNode->Contour[k].X))
+        k = j;
+    }
+  if (endType == etClosedPolygon && j < 2) {
+    delete newNode;
+    return;
+  }
+  m_polyNodes.AddChild(*newNode);
+
+  // if this path's lowest pt is lower than all the others then update m_lowest
+  if (endType != etClosedPolygon)
+    return;
+  if (m_lowest.X < 0)
+    m_lowest = IntPoint(m_polyNodes.ChildCount() - 1, k);
+  else {
+    IntPoint ip = m_polyNodes.Childs[(int)m_lowest.X]->Contour[(int)m_lowest.Y];
+    if (newNode->Contour[k].Y > ip.Y ||
+        (newNode->Contour[k].Y == ip.Y && newNode->Contour[k].X < ip.X))
+      m_lowest = IntPoint(m_polyNodes.ChildCount() - 1, k);
+  }
+}
+//------------------------------------------------------------------------------
+
+void ClipperOffset::AddPaths(const Paths &paths, JoinType joinType,
+                             EndType endType) {
+  for (Paths::size_type i = 0; i < paths.size(); ++i)
+    AddPath(paths[i], joinType, endType);
+}
+//------------------------------------------------------------------------------
+
+void ClipperOffset::FixOrientations() {
+  // fixup orientations of all closed paths if the orientation of the
+  // closed path with the lowermost vertex is wrong ...
+  if (m_lowest.X >= 0 &&
+      !Orientation(m_polyNodes.Childs[(int)m_lowest.X]->Contour)) {
+    for (int i = 0; i < m_polyNodes.ChildCount(); ++i) {
+      PolyNode &node = *m_polyNodes.Childs[i];
+      if (node.m_endtype == etClosedPolygon ||
+          (node.m_endtype == etClosedLine && Orientation(node.Contour)))
+        ReversePath(node.Contour);
+    }
+  } else {
+    for (int i = 0; i < m_polyNodes.ChildCount(); ++i) {
+      PolyNode &node = *m_polyNodes.Childs[i];
+      if (node.m_endtype == etClosedLine && !Orientation(node.Contour))
+        ReversePath(node.Contour);
+    }
+  }
+}
+//------------------------------------------------------------------------------
+
+void ClipperOffset::Execute(Paths &solution, double delta) {
+  solution.clear();
+  FixOrientations();
+  DoOffset(delta);
+
+  // now clean up 'corners' ...
+  Clipper clpr;
+  clpr.AddPaths(m_destPolys, ptSubject, true);
+  if (delta > 0) {
+    clpr.Execute(ctUnion, solution, pftPositive, pftPositive);
+  } else {
+    IntRect r = clpr.GetBounds();
+    Path outer(4);
+    outer[0] = IntPoint(r.left - 10, r.bottom + 10);
+    outer[1] = IntPoint(r.right + 10, r.bottom + 10);
+    outer[2] = IntPoint(r.right + 10, r.top - 10);
+    outer[3] = IntPoint(r.left - 10, r.top - 10);
+
+    clpr.AddPath(outer, ptSubject, true);
+    clpr.ReverseSolution(true);
+    clpr.Execute(ctUnion, solution, pftNegative, pftNegative);
+    if (solution.size() > 0)
+      solution.erase(solution.begin());
+  }
+}
+//------------------------------------------------------------------------------
+
+void ClipperOffset::Execute(PolyTree &solution, double delta) {
+  solution.Clear();
+  FixOrientations();
+  DoOffset(delta);
+
+  // now clean up 'corners' ...
+  Clipper clpr;
+  clpr.AddPaths(m_destPolys, ptSubject, true);
+  if (delta > 0) {
+    clpr.Execute(ctUnion, solution, pftPositive, pftPositive);
+  } else {
+    IntRect r = clpr.GetBounds();
+    Path outer(4);
+    outer[0] = IntPoint(r.left - 10, r.bottom + 10);
+    outer[1] = IntPoint(r.right + 10, r.bottom + 10);
+    outer[2] = IntPoint(r.right + 10, r.top - 10);
+    outer[3] = IntPoint(r.left - 10, r.top - 10);
+
+    clpr.AddPath(outer, ptSubject, true);
+    clpr.ReverseSolution(true);
+    clpr.Execute(ctUnion, solution, pftNegative, pftNegative);
+    // remove the outer PolyNode rectangle ...
+    if (solution.ChildCount() == 1 && solution.Childs[0]->ChildCount() > 0) {
+      PolyNode *outerNode = solution.Childs[0];
+      solution.Childs.reserve(outerNode->ChildCount());
+      solution.Childs[0] = outerNode->Childs[0];
+      solution.Childs[0]->Parent = outerNode->Parent;
+      for (int i = 1; i < outerNode->ChildCount(); ++i)
+        solution.AddChild(*outerNode->Childs[i]);
+    } else
+      solution.Clear();
+  }
+}
+//------------------------------------------------------------------------------
+
+void ClipperOffset::DoOffset(double delta) {
+  m_destPolys.clear();
+  m_delta = delta;
+
+  // if Zero offset, just copy any CLOSED polygons to m_p and return ...
+  if (NEAR_ZERO(delta)) {
+    m_destPolys.reserve(m_polyNodes.ChildCount());
+    for (int i = 0; i < m_polyNodes.ChildCount(); i++) {
+      PolyNode &node = *m_polyNodes.Childs[i];
+      if (node.m_endtype == etClosedPolygon)
+        m_destPolys.push_back(node.Contour);
+    }
+    return;
+  }
+
+  // see offset_triginometry3.svg in the documentation folder ...
+  if (MiterLimit > 2)
+    m_miterLim = 2 / (MiterLimit * MiterLimit);
+  else
+    m_miterLim = 0.5;
+
+  double y;
+  if (ArcTolerance <= 0.0)
+    y = def_arc_tolerance;
+  else if (ArcTolerance > std::fabs(delta) * def_arc_tolerance)
+    y = std::fabs(delta) * def_arc_tolerance;
+  else
+    y = ArcTolerance;
+  // see offset_triginometry2.svg in the documentation folder ...
+  double steps = pi / std::acos(1 - y / std::fabs(delta));
+  if (steps > std::fabs(delta) * pi)
+    steps = std::fabs(delta) * pi; // ie excessive precision check
+  m_sin = std::sin(two_pi / steps);
+  m_cos = std::cos(two_pi / steps);
+  m_StepsPerRad = steps / two_pi;
+  if (delta < 0.0)
+    m_sin = -m_sin;
+
+  m_destPolys.reserve(m_polyNodes.ChildCount() * 2);
+  for (int i = 0; i < m_polyNodes.ChildCount(); i++) {
+    PolyNode &node = *m_polyNodes.Childs[i];
+    m_srcPoly = node.Contour;
+
+    int len = (int)m_srcPoly.size();
+    if (len == 0 ||
+        (delta <= 0 && (len < 3 || node.m_endtype != etClosedPolygon)))
+      continue;
+
+    m_destPoly.clear();
+    if (len == 1) {
+      if (node.m_jointype == jtRound) {
+        double X = 1.0, Y = 0.0;
+        for (cInt j = 1; j <= steps; j++) {
+          m_destPoly.push_back(IntPoint(Round(m_srcPoly[0].X + X * delta),
+                                        Round(m_srcPoly[0].Y + Y * delta)));
+          double X2 = X;
+          X = X * m_cos - m_sin * Y;
+          Y = X2 * m_sin + Y * m_cos;
+        }
+      } else {
+        double X = -1.0, Y = -1.0;
+        for (int j = 0; j < 4; ++j) {
+          m_destPoly.push_back(IntPoint(Round(m_srcPoly[0].X + X * delta),
+                                        Round(m_srcPoly[0].Y + Y * delta)));
+          if (X < 0)
+            X = 1;
+          else if (Y < 0)
+            Y = 1;
+          else
+            X = -1;
+        }
+      }
+      m_destPolys.push_back(m_destPoly);
+      continue;
+    }
+    // build m_normals ...
+    m_normals.clear();
+    m_normals.reserve(len);
+    for (int j = 0; j < len - 1; ++j)
+      m_normals.push_back(GetUnitNormal(m_srcPoly[j], m_srcPoly[j + 1]));
+    if (node.m_endtype == etClosedLine || node.m_endtype == etClosedPolygon)
+      m_normals.push_back(GetUnitNormal(m_srcPoly[len - 1], m_srcPoly[0]));
+    else
+      m_normals.push_back(DoublePoint(m_normals[len - 2]));
+
+    if (node.m_endtype == etClosedPolygon) {
+      int k = len - 1;
+      for (int j = 0; j < len; ++j)
+        OffsetPoint(j, k, node.m_jointype);
+      m_destPolys.push_back(m_destPoly);
+    } else if (node.m_endtype == etClosedLine) {
+      int k = len - 1;
+      for (int j = 0; j < len; ++j)
+        OffsetPoint(j, k, node.m_jointype);
+      m_destPolys.push_back(m_destPoly);
+      m_destPoly.clear();
+      // re-build m_normals ...
+      DoublePoint n = m_normals[len - 1];
+      for (int j = len - 1; j > 0; j--)
+        m_normals[j] = DoublePoint(-m_normals[j - 1].X, -m_normals[j - 1].Y);
+      m_normals[0] = DoublePoint(-n.X, -n.Y);
+      k = 0;
+      for (int j = len - 1; j >= 0; j--)
+        OffsetPoint(j, k, node.m_jointype);
+      m_destPolys.push_back(m_destPoly);
+    } else {
+      int k = 0;
+      for (int j = 1; j < len - 1; ++j)
+        OffsetPoint(j, k, node.m_jointype);
+
+      IntPoint pt1;
+      if (node.m_endtype == etOpenButt) {
+        int j = len - 1;
+        pt1 = IntPoint((cInt)Round(m_srcPoly[j].X + m_normals[j].X * delta),
+                       (cInt)Round(m_srcPoly[j].Y + m_normals[j].Y * delta));
+        m_destPoly.push_back(pt1);
+        pt1 = IntPoint((cInt)Round(m_srcPoly[j].X - m_normals[j].X * delta),
+                       (cInt)Round(m_srcPoly[j].Y - m_normals[j].Y * delta));
+        m_destPoly.push_back(pt1);
+      } else {
+        int j = len - 1;
+        k = len - 2;
+        m_sinA = 0;
+        m_normals[j] = DoublePoint(-m_normals[j].X, -m_normals[j].Y);
+        if (node.m_endtype == etOpenSquare)
+          DoSquare(j, k);
+        else
+          DoRound(j, k);
+      }
+
+      // re-build m_normals ...
+      for (int j = len - 1; j > 0; j--)
+        m_normals[j] = DoublePoint(-m_normals[j - 1].X, -m_normals[j - 1].Y);
+      m_normals[0] = DoublePoint(-m_normals[1].X, -m_normals[1].Y);
+
+      k = len - 1;
+      for (int j = k - 1; j > 0; --j)
+        OffsetPoint(j, k, node.m_jointype);
+
+      if (node.m_endtype == etOpenButt) {
+        pt1 = IntPoint((cInt)Round(m_srcPoly[0].X - m_normals[0].X * delta),
+                       (cInt)Round(m_srcPoly[0].Y - m_normals[0].Y * delta));
+        m_destPoly.push_back(pt1);
+        pt1 = IntPoint((cInt)Round(m_srcPoly[0].X + m_normals[0].X * delta),
+                       (cInt)Round(m_srcPoly[0].Y + m_normals[0].Y * delta));
+        m_destPoly.push_back(pt1);
+      } else {
+        k = 1;
+        m_sinA = 0;
+        if (node.m_endtype == etOpenSquare)
+          DoSquare(0, 1);
+        else
+          DoRound(0, 1);
+      }
+      m_destPolys.push_back(m_destPoly);
+    }
+  }
+}
+//------------------------------------------------------------------------------
+
+void ClipperOffset::OffsetPoint(int j, int &k, JoinType jointype) {
+  // cross product ...
+  m_sinA = (m_normals[k].X * m_normals[j].Y - m_normals[j].X * m_normals[k].Y);
+  if (std::fabs(m_sinA * m_delta) < 1.0) {
+    // dot product ...
+    double cosA =
+        (m_normals[k].X * m_normals[j].X + m_normals[j].Y * m_normals[k].Y);
+    if (cosA > 0) // angle => 0 degrees
+    {
+      m_destPoly.push_back(
+          IntPoint(Round(m_srcPoly[j].X + m_normals[k].X * m_delta),
+                   Round(m_srcPoly[j].Y + m_normals[k].Y * m_delta)));
+      return;
+    }
+    // else angle => 180 degrees
+  } else if (m_sinA > 1.0)
+    m_sinA = 1.0;
+  else if (m_sinA < -1.0)
+    m_sinA = -1.0;
+
+  if (m_sinA * m_delta < 0) {
+    m_destPoly.push_back(
+        IntPoint(Round(m_srcPoly[j].X + m_normals[k].X * m_delta),
+                 Round(m_srcPoly[j].Y + m_normals[k].Y * m_delta)));
+    m_destPoly.push_back(m_srcPoly[j]);
+    m_destPoly.push_back(
+        IntPoint(Round(m_srcPoly[j].X + m_normals[j].X * m_delta),
+                 Round(m_srcPoly[j].Y + m_normals[j].Y * m_delta)));
+  } else
+    switch (jointype) {
+    case jtMiter: {
+      double r = 1 + (m_normals[j].X * m_normals[k].X +
+                      m_normals[j].Y * m_normals[k].Y);
+      if (r >= m_miterLim)
+        DoMiter(j, k, r);
+      else
+        DoSquare(j, k);
+      break;
+    }
+    case jtSquare:
+      DoSquare(j, k);
+      break;
+    case jtRound:
+      DoRound(j, k);
+      break;
+    }
+  k = j;
+}
+//------------------------------------------------------------------------------
+
+void ClipperOffset::DoSquare(int j, int k) {
+  double dx = std::tan(std::atan2(m_sinA, m_normals[k].X * m_normals[j].X +
+                                              m_normals[k].Y * m_normals[j].Y) /
+                       4);
+  m_destPoly.push_back(IntPoint(
+      Round(m_srcPoly[j].X + m_delta * (m_normals[k].X - m_normals[k].Y * dx)),
+      Round(m_srcPoly[j].Y +
+            m_delta * (m_normals[k].Y + m_normals[k].X * dx))));
+  m_destPoly.push_back(IntPoint(
+      Round(m_srcPoly[j].X + m_delta * (m_normals[j].X + m_normals[j].Y * dx)),
+      Round(m_srcPoly[j].Y +
+            m_delta * (m_normals[j].Y - m_normals[j].X * dx))));
+}
+//------------------------------------------------------------------------------
+
+void ClipperOffset::DoMiter(int j, int k, double r) {
+  double q = m_delta / r;
+  m_destPoly.push_back(
+      IntPoint(Round(m_srcPoly[j].X + (m_normals[k].X + m_normals[j].X) * q),
+               Round(m_srcPoly[j].Y + (m_normals[k].Y + m_normals[j].Y) * q)));
+}
+//------------------------------------------------------------------------------
+
+void ClipperOffset::DoRound(int j, int k) {
+  double a = std::atan2(m_sinA, m_normals[k].X * m_normals[j].X +
+                                    m_normals[k].Y * m_normals[j].Y);
+  int steps = std::max((int)Round(m_StepsPerRad * std::fabs(a)), 1);
+
+  double X = m_normals[k].X, Y = m_normals[k].Y, X2;
+  for (int i = 0; i < steps; ++i) {
+    m_destPoly.push_back(IntPoint(Round(m_srcPoly[j].X + X * m_delta),
+                                  Round(m_srcPoly[j].Y + Y * m_delta)));
+    X2 = X;
+    X = X * m_cos - m_sin * Y;
+    Y = X2 * m_sin + Y * m_cos;
+  }
+  m_destPoly.push_back(
+      IntPoint(Round(m_srcPoly[j].X + m_normals[j].X * m_delta),
+               Round(m_srcPoly[j].Y + m_normals[j].Y * m_delta)));
+}
+
+//------------------------------------------------------------------------------
+// Miscellaneous public functions
+//------------------------------------------------------------------------------
+
+void Clipper::DoSimplePolygons() {
+  PolyOutList::size_type i = 0;
+  while (i < m_PolyOuts.size()) {
+    OutRec *outrec = m_PolyOuts[i++];
+    OutPt *op = outrec->Pts;
+    if (!op || outrec->IsOpen)
+      continue;
+    do // for each Pt in Polygon until duplicate found do ...
+    {
+      OutPt *op2 = op->Next;
+      while (op2 != outrec->Pts) {
+        if ((op->Pt == op2->Pt) && op2->Next != op && op2->Prev != op) {
+          // split the polygon into two ...
+          OutPt *op3 = op->Prev;
+          OutPt *op4 = op2->Prev;
+          op->Prev = op4;
+          op4->Next = op;
+          op2->Prev = op3;
+          op3->Next = op2;
+
+          outrec->Pts = op;
+          OutRec *outrec2 = CreateOutRec();
+          outrec2->Pts = op2;
+          UpdateOutPtIdxs(*outrec2);
+          if (Poly2ContainsPoly1(outrec2->Pts, outrec->Pts)) {
+            // OutRec2 is contained by OutRec1 ...
+            outrec2->IsHole = !outrec->IsHole;
+            outrec2->FirstLeft = outrec;
+            if (m_UsingPolyTree)
+              FixupFirstLefts2(outrec2, outrec);
+          } else if (Poly2ContainsPoly1(outrec->Pts, outrec2->Pts)) {
+            // OutRec1 is contained by OutRec2 ...
+            outrec2->IsHole = outrec->IsHole;
+            outrec->IsHole = !outrec2->IsHole;
+            outrec2->FirstLeft = outrec->FirstLeft;
+            outrec->FirstLeft = outrec2;
+            if (m_UsingPolyTree)
+              FixupFirstLefts2(outrec, outrec2);
+          } else {
+            // the 2 polygons are separate ...
+            outrec2->IsHole = outrec->IsHole;
+            outrec2->FirstLeft = outrec->FirstLeft;
+            if (m_UsingPolyTree)
+              FixupFirstLefts1(outrec, outrec2);
+          }
+          op2 = op; // ie get ready for the Next iteration
+        }
+        op2 = op2->Next;
+      }
+      op = op->Next;
+    } while (op != outrec->Pts);
+  }
+}
+//------------------------------------------------------------------------------
+
+void ReversePath(Path &p) { std::reverse(p.begin(), p.end()); }
+//------------------------------------------------------------------------------
+
+void ReversePaths(Paths &p) {
+  for (Paths::size_type i = 0; i < p.size(); ++i)
+    ReversePath(p[i]);
+}
+//------------------------------------------------------------------------------
+
+void SimplifyPolygon(const Path &in_poly, Paths &out_polys,
+                     PolyFillType fillType) {
+  Clipper c;
+  c.StrictlySimple(true);
+  c.AddPath(in_poly, ptSubject, true);
+  c.Execute(ctUnion, out_polys, fillType, fillType);
+}
+//------------------------------------------------------------------------------
+
+void SimplifyPolygons(const Paths &in_polys, Paths &out_polys,
+                      PolyFillType fillType) {
+  Clipper c;
+  c.StrictlySimple(true);
+  c.AddPaths(in_polys, ptSubject, true);
+  c.Execute(ctUnion, out_polys, fillType, fillType);
+}
+//------------------------------------------------------------------------------
+
+void SimplifyPolygons(Paths &polys, PolyFillType fillType) {
+  SimplifyPolygons(polys, polys, fillType);
+}
+//------------------------------------------------------------------------------
+
+inline double DistanceSqrd(const IntPoint &pt1, const IntPoint &pt2) {
+  double Dx = ((double)pt1.X - pt2.X);
+  double dy = ((double)pt1.Y - pt2.Y);
+  return (Dx * Dx + dy * dy);
+}
+//------------------------------------------------------------------------------
+
+double DistanceFromLineSqrd(const IntPoint &pt, const IntPoint &ln1,
+                            const IntPoint &ln2) {
+  // The equation of a line in general form (Ax + By + C = 0)
+  // given 2 points (x�,y�) & (x�,y�) is ...
+  //(y� - y�)x + (x� - x�)y + (y� - y�)x� - (x� - x�)y� = 0
+  // A = (y� - y�); B = (x� - x�); C = (y� - y�)x� - (x� - x�)y�
+  // perpendicular distance of point (x�,y�) = (Ax� + By� + C)/Sqrt(A� + B�)
+  // see http://en.wikipedia.org/wiki/Perpendicular_distance
+  double A = double(ln1.Y - ln2.Y);
+  double B = double(ln2.X - ln1.X);
+  double C = A * ln1.X + B * ln1.Y;
+  C = A * pt.X + B * pt.Y - C;
+  return (C * C) / (A * A + B * B);
+}
+//---------------------------------------------------------------------------
+
+bool SlopesNearCollinear(const IntPoint &pt1, const IntPoint &pt2,
+                         const IntPoint &pt3, double distSqrd) {
+  // this function is more accurate when the point that's geometrically
+  // between the other 2 points is the one that's tested for distance.
+  // ie makes it more likely to pick up 'spikes' ...
+  if (Abs(pt1.X - pt2.X) > Abs(pt1.Y - pt2.Y)) {
+    if ((pt1.X > pt2.X) == (pt1.X < pt3.X))
+      return DistanceFromLineSqrd(pt1, pt2, pt3) < distSqrd;
+    else if ((pt2.X > pt1.X) == (pt2.X < pt3.X))
+      return DistanceFromLineSqrd(pt2, pt1, pt3) < distSqrd;
+    else
+      return DistanceFromLineSqrd(pt3, pt1, pt2) < distSqrd;
+  } else {
+    if ((pt1.Y > pt2.Y) == (pt1.Y < pt3.Y))
+      return DistanceFromLineSqrd(pt1, pt2, pt3) < distSqrd;
+    else if ((pt2.Y > pt1.Y) == (pt2.Y < pt3.Y))
+      return DistanceFromLineSqrd(pt2, pt1, pt3) < distSqrd;
+    else
+      return DistanceFromLineSqrd(pt3, pt1, pt2) < distSqrd;
+  }
+}
+//------------------------------------------------------------------------------
+
+bool PointsAreClose(IntPoint pt1, IntPoint pt2, double distSqrd) {
+  double Dx = (double)pt1.X - pt2.X;
+  double dy = (double)pt1.Y - pt2.Y;
+  return ((Dx * Dx) + (dy * dy) <= distSqrd);
+}
+//------------------------------------------------------------------------------
+
+OutPt *ExcludeOp(OutPt *op) {
+  OutPt *result = op->Prev;
+  result->Next = op->Next;
+  op->Next->Prev = result;
+  result->Idx = 0;
+  return result;
+}
+//------------------------------------------------------------------------------
+
+void CleanPolygon(const Path &in_poly, Path &out_poly, double distance) {
+  // distance = proximity in units/pixels below which vertices
+  // will be stripped. Default ~= sqrt(2).
+
+  size_t size = in_poly.size();
+
+  if (size == 0) {
+    out_poly.clear();
+    return;
+  }
+
+  OutPt *outPts = new OutPt[size];
+  for (size_t i = 0; i < size; ++i) {
+    outPts[i].Pt = in_poly[i];
+    outPts[i].Next = &outPts[(i + 1) % size];
+    outPts[i].Next->Prev = &outPts[i];
+    outPts[i].Idx = 0;
+  }
+
+  double distSqrd = distance * distance;
+  OutPt *op = &outPts[0];
+  while (op->Idx == 0 && op->Next != op->Prev) {
+    if (PointsAreClose(op->Pt, op->Prev->Pt, distSqrd)) {
+      op = ExcludeOp(op);
+      size--;
+    } else if (PointsAreClose(op->Prev->Pt, op->Next->Pt, distSqrd)) {
+      ExcludeOp(op->Next);
+      op = ExcludeOp(op);
+      size -= 2;
+    } else if (SlopesNearCollinear(op->Prev->Pt, op->Pt, op->Next->Pt,
+                                   distSqrd)) {
+      op = ExcludeOp(op);
+      size--;
+    } else {
+      op->Idx = 1;
+      op = op->Next;
+    }
+  }
+
+  if (size < 3)
+    size = 0;
+  out_poly.resize(size);
+  for (size_t i = 0; i < size; ++i) {
+    out_poly[i] = op->Pt;
+    op = op->Next;
+  }
+  delete[] outPts;
+}
+//------------------------------------------------------------------------------
+
+void CleanPolygon(Path &poly, double distance) {
+  CleanPolygon(poly, poly, distance);
+}
+//------------------------------------------------------------------------------
+
+void CleanPolygons(const Paths &in_polys, Paths &out_polys, double distance) {
+  out_polys.resize(in_polys.size());
+  for (Paths::size_type i = 0; i < in_polys.size(); ++i)
+    CleanPolygon(in_polys[i], out_polys[i], distance);
+}
+//------------------------------------------------------------------------------
+
+void CleanPolygons(Paths &polys, double distance) {
+  CleanPolygons(polys, polys, distance);
+}
+//------------------------------------------------------------------------------
+
+void Minkowski(const Path &poly, const Path &path, Paths &solution, bool isSum,
+               bool isClosed) {
+  int delta = (isClosed ? 1 : 0);
+  size_t polyCnt = poly.size();
+  size_t pathCnt = path.size();
+  Paths pp;
+  pp.reserve(pathCnt);
+  if (isSum)
+    for (size_t i = 0; i < pathCnt; ++i) {
+      Path p;
+      p.reserve(polyCnt);
+      for (size_t j = 0; j < poly.size(); ++j)
+        p.push_back(IntPoint(path[i].X + poly[j].X, path[i].Y + poly[j].Y));
+      pp.push_back(p);
+    }
+  else
+    for (size_t i = 0; i < pathCnt; ++i) {
+      Path p;
+      p.reserve(polyCnt);
+      for (size_t j = 0; j < poly.size(); ++j)
+        p.push_back(IntPoint(path[i].X - poly[j].X, path[i].Y - poly[j].Y));
+      pp.push_back(p);
+    }
+
+  solution.clear();
+  solution.reserve((pathCnt + delta) * (polyCnt + 1));
+  for (size_t i = 0; i < pathCnt - 1 + delta; ++i)
+    for (size_t j = 0; j < polyCnt; ++j) {
+      Path quad;
+      quad.reserve(4);
+      quad.push_back(pp[i % pathCnt][j % polyCnt]);
+      quad.push_back(pp[(i + 1) % pathCnt][j % polyCnt]);
+      quad.push_back(pp[(i + 1) % pathCnt][(j + 1) % polyCnt]);
+      quad.push_back(pp[i % pathCnt][(j + 1) % polyCnt]);
+      if (!Orientation(quad))
+        ReversePath(quad);
+      solution.push_back(quad);
+    }
+}
+//------------------------------------------------------------------------------
+
+void MinkowskiSum(const Path &pattern, const Path &path, Paths &solution,
+                  bool pathIsClosed) {
+  Minkowski(pattern, path, solution, true, pathIsClosed);
+  Clipper c;
+  c.AddPaths(solution, ptSubject, true);
+  c.Execute(ctUnion, solution, pftNonZero, pftNonZero);
+}
+//------------------------------------------------------------------------------
+
+void TranslatePath(const Path &input, Path &output, const IntPoint delta) {
+  // precondition: input != output
+  output.resize(input.size());
+  for (size_t i = 0; i < input.size(); ++i)
+    output[i] = IntPoint(input[i].X + delta.X, input[i].Y + delta.Y);
+}
+//------------------------------------------------------------------------------
+
+void MinkowskiSum(const Path &pattern, const Paths &paths, Paths &solution,
+                  bool pathIsClosed) {
+  Clipper c;
+  for (size_t i = 0; i < paths.size(); ++i) {
+    Paths tmp;
+    Minkowski(pattern, paths[i], tmp, true, pathIsClosed);
+    c.AddPaths(tmp, ptSubject, true);
+    if (pathIsClosed) {
+      Path tmp2;
+      TranslatePath(paths[i], tmp2, pattern[0]);
+      c.AddPath(tmp2, ptClip, true);
+    }
+  }
+  c.Execute(ctUnion, solution, pftNonZero, pftNonZero);
+}
+//------------------------------------------------------------------------------
+
+void MinkowskiDiff(const Path &poly1, const Path &poly2, Paths &solution) {
+  Minkowski(poly1, poly2, solution, false, true);
+  Clipper c;
+  c.AddPaths(solution, ptSubject, true);
+  c.Execute(ctUnion, solution, pftNonZero, pftNonZero);
+}
+//------------------------------------------------------------------------------
+
+enum NodeType { ntAny, ntOpen, ntClosed };
+
+void AddPolyNodeToPaths(const PolyNode &polynode, NodeType nodetype,
+                        Paths &paths) {
+  bool match = true;
+  if (nodetype == ntClosed)
+    match = !polynode.IsOpen();
+  else if (nodetype == ntOpen)
+    return;
+
+  if (!polynode.Contour.empty() && match)
+    paths.push_back(polynode.Contour);
+  for (int i = 0; i < polynode.ChildCount(); ++i)
+    AddPolyNodeToPaths(*polynode.Childs[i], nodetype, paths);
+}
+//------------------------------------------------------------------------------
+
+void PolyTreeToPaths(const PolyTree &polytree, Paths &paths) {
+  paths.resize(0);
+  paths.reserve(polytree.Total());
+  AddPolyNodeToPaths(polytree, ntAny, paths);
+}
+//------------------------------------------------------------------------------
+
+void ClosedPathsFromPolyTree(const PolyTree &polytree, Paths &paths) {
+  paths.resize(0);
+  paths.reserve(polytree.Total());
+  AddPolyNodeToPaths(polytree, ntClosed, paths);
+}
+//------------------------------------------------------------------------------
+
+void OpenPathsFromPolyTree(PolyTree &polytree, Paths &paths) {
+  paths.resize(0);
+  paths.reserve(polytree.Total());
+  // Open paths are top level only, so ...
+  for (int i = 0; i < polytree.ChildCount(); ++i)
+    if (polytree.Childs[i]->IsOpen())
+      paths.push_back(polytree.Childs[i]->Contour);
+}
+//------------------------------------------------------------------------------
+
+std::ostream &operator<<(std::ostream &s, const IntPoint &p) {
+  s << "(" << p.X << "," << p.Y << ")";
+  return s;
+}
+//------------------------------------------------------------------------------
+
+std::ostream &operator<<(std::ostream &s, const Path &p) {
+  if (p.empty())
+    return s;
+  Path::size_type last = p.size() - 1;
+  for (Path::size_type i = 0; i < last; i++)
+    s << "(" << p[i].X << "," << p[i].Y << "), ";
+  s << "(" << p[last].X << "," << p[last].Y << ")\n";
+  return s;
+}
+//------------------------------------------------------------------------------
+
+std::ostream &operator<<(std::ostream &s, const Paths &p) {
+  for (Paths::size_type i = 0; i < p.size(); i++)
+    s << p[i];
+  s << "\n";
+  return s;
+}
+//------------------------------------------------------------------------------
+
+} // ClipperLib namespace

deploy/android_demo/app/src/main/cpp/ocr_clipper.hpp

+/*******************************************************************************
+*                                                                              *
+* Author    :  Angus Johnson                                                   *
+* Version   :  6.4.2                                                           *
+* Date      :  27 February 2017                                                *
+* Website   :  http://www.angusj.com                                           *
+* Copyright :  Angus Johnson 2010-2017                                         *
+*                                                                              *
+* License:                                                                     *
+* Use, modification & distribution is subject to Boost Software License Ver 1. *
+* http://www.boost.org/LICENSE_1_0.txt                                         *
+*                                                                              *
+* Attributions:                                                                *
+* The code in this library is an extension of Bala Vatti's clipping algorithm: *
+* "A generic solution to polygon clipping"                                     *
+* Communications of the ACM, Vol 35, Issue 7 (July 1992) pp 56-63.             *
+* http://portal.acm.org/citation.cfm?id=129906                                 *
+*                                                                              *
+* Computer graphics and geometric modeling: implementation and algorithms      *
+* By Max K. Agoston                                                            *
+* Springer; 1 edition (January 4, 2005)                                        *
+* http://books.google.com/books?q=vatti+clipping+agoston                       *
+*                                                                              *
+* See also:                                                                    *
+* "Polygon Offsetting by Computing Winding Numbers"                            *
+* Paper no. DETC2005-85513 pp. 565-575                                         *
+* ASME 2005 International Design Engineering Technical Conferences             *
+* and Computers and Information in Engineering Conference (IDETC/CIE2005)      *
+* September 24-28, 2005 , Long Beach, California, USA                          *
+* http://www.me.berkeley.edu/~mcmains/pubs/DAC05OffsetPolygon.pdf              *
+*                                                                              *
+*******************************************************************************/
+
+#ifndef clipper_hpp
+#define clipper_hpp
+
+#define CLIPPER_VERSION "6.4.2"
+
+// use_int32: When enabled 32bit ints are used instead of 64bit ints. This
+// improve performance but coordinate values are limited to the range +/- 46340
+//#define use_int32
+
+// use_xyz: adds a Z member to IntPoint. Adds a minor cost to perfomance.
+//#define use_xyz
+
+// use_lines: Enables line clipping. Adds a very minor cost to performance.
+#define use_lines
+
+// use_deprecated: Enables temporary support for the obsolete functions
+//#define use_deprecated
+
+#include <cstdlib>
+#include <cstring>
+#include <functional>
+#include <list>
+#include <ostream>
+#include <queue>
+#include <set>
+#include <stdexcept>
+#include <vector>
+
+namespace ClipperLib {
+
+enum ClipType { ctIntersection, ctUnion, ctDifference, ctXor };
+enum PolyType { ptSubject, ptClip };
+// By far the most widely used winding rules for polygon filling are
+// EvenOdd & NonZero (GDI, GDI+, XLib, OpenGL, Cairo, AGG, Quartz, SVG, Gr32)
+// Others rules include Positive, Negative and ABS_GTR_EQ_TWO (only in OpenGL)
+// see http://glprogramming.com/red/chapter11.html
+enum PolyFillType { pftEvenOdd, pftNonZero, pftPositive, pftNegative };
+
+#ifdef use_int32
+typedef int cInt;
+static cInt const loRange = 0x7FFF;
+static cInt const hiRange = 0x7FFF;
+#else
+typedef signed long long cInt;
+static cInt const loRange = 0x3FFFFFFF;
+static cInt const hiRange = 0x3FFFFFFFFFFFFFFFLL;
+typedef signed long long long64; // used by Int128 class
+typedef unsigned long long ulong64;
+
+#endif
+
+struct IntPoint {
+  cInt X;
+  cInt Y;
+#ifdef use_xyz
+  cInt Z;
+  IntPoint(cInt x = 0, cInt y = 0, cInt z = 0) : X(x), Y(y), Z(z){};
+#else
+
+  IntPoint(cInt x = 0, cInt y = 0) : X(x), Y(y){};
+#endif
+
+  friend inline bool operator==(const IntPoint &a, const IntPoint &b) {
+    return a.X == b.X && a.Y == b.Y;
+  }
+
+  friend inline bool operator!=(const IntPoint &a, const IntPoint &b) {
+    return a.X != b.X || a.Y != b.Y;
+  }
+};
+//------------------------------------------------------------------------------
+
+typedef std::vector<IntPoint> Path;
+typedef std::vector<Path> Paths;
+
+inline Path &operator<<(Path &poly, const IntPoint &p) {
+  poly.push_back(p);
+  return poly;
+}
+
+inline Paths &operator<<(Paths &polys, const Path &p) {
+  polys.push_back(p);
+  return polys;
+}
+
+std::ostream &operator<<(std::ostream &s, const IntPoint &p);
+
+std::ostream &operator<<(std::ostream &s, const Path &p);
+
+std::ostream &operator<<(std::ostream &s, const Paths &p);
+
+struct DoublePoint {
+  double X;
+  double Y;
+
+  DoublePoint(double x = 0, double y = 0) : X(x), Y(y) {}
+
+  DoublePoint(IntPoint ip) : X((double)ip.X), Y((double)ip.Y) {}
+};
+//------------------------------------------------------------------------------
+
+#ifdef use_xyz
+typedef void (*ZFillCallback)(IntPoint &e1bot, IntPoint &e1top, IntPoint &e2bot,
+                              IntPoint &e2top, IntPoint &pt);
+#endif
+
+enum InitOptions {
+  ioReverseSolution = 1,
+  ioStrictlySimple = 2,
+  ioPreserveCollinear = 4
+};
+enum JoinType { jtSquare, jtRound, jtMiter };
+enum EndType {
+  etClosedPolygon,
+  etClosedLine,
+  etOpenButt,
+  etOpenSquare,
+  etOpenRound
+};
+
+class PolyNode;
+
+typedef std::vector<PolyNode *> PolyNodes;
+
+class PolyNode {
+public:
+  PolyNode();
+
+  virtual ~PolyNode(){};
+  Path Contour;
+  PolyNodes Childs;
+  PolyNode *Parent;
+
+  PolyNode *GetNext() const;
+
+  bool IsHole() const;
+
+  bool IsOpen() const;
+
+  int ChildCount() const;
+
+private:
+  // PolyNode& operator =(PolyNode& other);
+  unsigned Index; // node index in Parent.Childs
+  bool m_IsOpen;
+  JoinType m_jointype;
+  EndType m_endtype;
+
+  PolyNode *GetNextSiblingUp() const;
+
+  void AddChild(PolyNode &child);
+
+  friend class Clipper; // to access Index
+  friend class ClipperOffset;
+};
+
+class PolyTree : public PolyNode {
+public:
+  ~PolyTree() { Clear(); };
+
+  PolyNode *GetFirst() const;
+
+  void Clear();
+
+  int Total() const;
+
+private:
+  // PolyTree& operator =(PolyTree& other);
+  PolyNodes AllNodes;
+
+  friend class Clipper; // to access AllNodes
+};
+
+bool Orientation(const Path &poly);
+
+double Area(const Path &poly);
+
+int PointInPolygon(const IntPoint &pt, const Path &path);
+
+void SimplifyPolygon(const Path &in_poly, Paths &out_polys,
+                     PolyFillType fillType = pftEvenOdd);
+
+void SimplifyPolygons(const Paths &in_polys, Paths &out_polys,
+                      PolyFillType fillType = pftEvenOdd);
+
+void SimplifyPolygons(Paths &polys, PolyFillType fillType = pftEvenOdd);
+
+void CleanPolygon(const Path &in_poly, Path &out_poly, double distance = 1.415);
+
+void CleanPolygon(Path &poly, double distance = 1.415);
+
+void CleanPolygons(const Paths &in_polys, Paths &out_polys,
+                   double distance = 1.415);
+
+void CleanPolygons(Paths &polys, double distance = 1.415);
+
+void MinkowskiSum(const Path &pattern, const Path &path, Paths &solution,
+                  bool pathIsClosed);
+
+void MinkowskiSum(const Path &pattern, const Paths &paths, Paths &solution,
+                  bool pathIsClosed);
+
+void MinkowskiDiff(const Path &poly1, const Path &poly2, Paths &solution);
+
+void PolyTreeToPaths(const PolyTree &polytree, Paths &paths);
+
+void ClosedPathsFromPolyTree(const PolyTree &polytree, Paths &paths);
+
+void OpenPathsFromPolyTree(PolyTree &polytree, Paths &paths);
+
+void ReversePath(Path &p);
+
+void ReversePaths(Paths &p);
+
+struct IntRect {
+  cInt left;
+  cInt top;
+  cInt right;
+  cInt bottom;
+};
+
+// enums that are used internally ...
+enum EdgeSide { esLeft = 1, esRight = 2 };
+
+// forward declarations (for stuff used internally) ...
+struct TEdge;
+struct IntersectNode;
+struct LocalMinimum;
+struct OutPt;
+struct OutRec;
+struct Join;
+
+typedef std::vector<OutRec *> PolyOutList;
+typedef std::vector<TEdge *> EdgeList;
+typedef std::vector<Join *> JoinList;
+typedef std::vector<IntersectNode *> IntersectList;
+
+//------------------------------------------------------------------------------
+
+// ClipperBase is the ancestor to the Clipper class. It should not be
+// instantiated directly. This class simply abstracts the conversion of sets of
+// polygon coordinates into edge objects that are stored in a LocalMinima list.
+class ClipperBase {
+public:
+  ClipperBase();
+
+  virtual ~ClipperBase();
+
+  virtual bool AddPath(const Path &pg, PolyType PolyTyp, bool Closed);
+
+  bool AddPaths(const Paths &ppg, PolyType PolyTyp, bool Closed);
+
+  virtual void Clear();
+
+  IntRect GetBounds();
+
+  bool PreserveCollinear() { return m_PreserveCollinear; };
+
+  void PreserveCollinear(bool value) { m_PreserveCollinear = value; };
+
+protected:
+  void DisposeLocalMinimaList();
+
+  TEdge *AddBoundsToLML(TEdge *e, bool IsClosed);
+
+  virtual void Reset();
+
+  TEdge *ProcessBound(TEdge *E, bool IsClockwise);
+
+  void InsertScanbeam(const cInt Y);
+
+  bool PopScanbeam(cInt &Y);
+
+  bool LocalMinimaPending();
+
+  bool PopLocalMinima(cInt Y, const LocalMinimum *&locMin);
+
+  OutRec *CreateOutRec();
+
+  void DisposeAllOutRecs();
+
+  void DisposeOutRec(PolyOutList::size_type index);
+
+  void SwapPositionsInAEL(TEdge *edge1, TEdge *edge2);
+
+  void DeleteFromAEL(TEdge *e);
+
+  void UpdateEdgeIntoAEL(TEdge *&e);
+
+  typedef std::vector<LocalMinimum> MinimaList;
+  MinimaList::iterator m_CurrentLM;
+  MinimaList m_MinimaList;
+
+  bool m_UseFullRange;
+  EdgeList m_edges;
+  bool m_PreserveCollinear;
+  bool m_HasOpenPaths;
+  PolyOutList m_PolyOuts;
+  TEdge *m_ActiveEdges;
+
+  typedef std::priority_queue<cInt> ScanbeamList;
+  ScanbeamList m_Scanbeam;
+};
+//------------------------------------------------------------------------------
+
+class Clipper : public virtual ClipperBase {
+public:
+  Clipper(int initOptions = 0);
+
+  bool Execute(ClipType clipType, Paths &solution,
+               PolyFillType fillType = pftEvenOdd);
+
+  bool Execute(ClipType clipType, Paths &solution, PolyFillType subjFillType,
+               PolyFillType clipFillType);
+
+  bool Execute(ClipType clipType, PolyTree &polytree,
+               PolyFillType fillType = pftEvenOdd);
+
+  bool Execute(ClipType clipType, PolyTree &polytree, PolyFillType subjFillType,
+               PolyFillType clipFillType);
+
+  bool ReverseSolution() { return m_ReverseOutput; };
+
+  void ReverseSolution(bool value) { m_ReverseOutput = value; };
+
+  bool StrictlySimple() { return m_StrictSimple; };
+
+  void StrictlySimple(bool value) { m_StrictSimple = value; };
+// set the callback function for z value filling on intersections (otherwise Z
+// is 0)
+#ifdef use_xyz
+  void ZFillFunction(ZFillCallback zFillFunc);
+#endif
+protected:
+  virtual bool ExecuteInternal();
+
+private:
+  JoinList m_Joins;
+  JoinList m_GhostJoins;
+  IntersectList m_IntersectList;
+  ClipType m_ClipType;
+  typedef std::list<cInt> MaximaList;
+  MaximaList m_Maxima;
+  TEdge *m_SortedEdges;
+  bool m_ExecuteLocked;
+  PolyFillType m_ClipFillType;
+  PolyFillType m_SubjFillType;
+  bool m_ReverseOutput;
+  bool m_UsingPolyTree;
+  bool m_StrictSimple;
+#ifdef use_xyz
+  ZFillCallback m_ZFill; // custom callback
+#endif
+
+  void SetWindingCount(TEdge &edge);
+
+  bool IsEvenOddFillType(const TEdge &edge) const;
+
+  bool IsEvenOddAltFillType(const TEdge &edge) const;
+
+  void InsertLocalMinimaIntoAEL(const cInt botY);
+
+  void InsertEdgeIntoAEL(TEdge *edge, TEdge *startEdge);
+
+  void AddEdgeToSEL(TEdge *edge);
+
+  bool PopEdgeFromSEL(TEdge *&edge);
+
+  void CopyAELToSEL();
+
+  void DeleteFromSEL(TEdge *e);
+
+  void SwapPositionsInSEL(TEdge *edge1, TEdge *edge2);
+
+  bool IsContributing(const TEdge &edge) const;
+
+  bool IsTopHorz(const cInt XPos);
+
+  void DoMaxima(TEdge *e);
+
+  void ProcessHorizontals();
+
+  void ProcessHorizontal(TEdge *horzEdge);
+
+  void AddLocalMaxPoly(TEdge *e1, TEdge *e2, const IntPoint &pt);
+
+  OutPt *AddLocalMinPoly(TEdge *e1, TEdge *e2, const IntPoint &pt);
+
+  OutRec *GetOutRec(int idx);
+
+  void AppendPolygon(TEdge *e1, TEdge *e2);
+
+  void IntersectEdges(TEdge *e1, TEdge *e2, IntPoint &pt);
+
+  OutPt *AddOutPt(TEdge *e, const IntPoint &pt);
+
+  OutPt *GetLastOutPt(TEdge *e);
+
+  bool ProcessIntersections(const cInt topY);
+
+  void BuildIntersectList(const cInt topY);
+
+  void ProcessIntersectList();
+
+  void ProcessEdgesAtTopOfScanbeam(const cInt topY);
+
+  void BuildResult(Paths &polys);
+
+  void BuildResult2(PolyTree &polytree);
+
+  void SetHoleState(TEdge *e, OutRec *outrec);
+
+  void DisposeIntersectNodes();
+
+  bool FixupIntersectionOrder();
+
+  void FixupOutPolygon(OutRec &outrec);
+
+  void FixupOutPolyline(OutRec &outrec);
+
+  bool IsHole(TEdge *e);
+
+  bool FindOwnerFromSplitRecs(OutRec &outRec, OutRec *&currOrfl);
+
+  void FixHoleLinkage(OutRec &outrec);
+
+  void AddJoin(OutPt *op1, OutPt *op2, const IntPoint offPt);
+
+  void ClearJoins();
+
+  void ClearGhostJoins();
+
+  void AddGhostJoin(OutPt *op, const IntPoint offPt);
+
+  bool JoinPoints(Join *j, OutRec *outRec1, OutRec *outRec2);
+
+  void JoinCommonEdges();
+
+  void DoSimplePolygons();
+
+  void FixupFirstLefts1(OutRec *OldOutRec, OutRec *NewOutRec);
+
+  void FixupFirstLefts2(OutRec *InnerOutRec, OutRec *OuterOutRec);
+
+  void FixupFirstLefts3(OutRec *OldOutRec, OutRec *NewOutRec);
+
+#ifdef use_xyz
+  void SetZ(IntPoint &pt, TEdge &e1, TEdge &e2);
+#endif
+};
+//------------------------------------------------------------------------------
+
+class ClipperOffset {
+public:
+  ClipperOffset(double miterLimit = 2.0, double roundPrecision = 0.25);
+
+  ~ClipperOffset();
+
+  void AddPath(const Path &path, JoinType joinType, EndType endType);
+
+  void AddPaths(const Paths &paths, JoinType joinType, EndType endType);
+
+  void Execute(Paths &solution, double delta);
+
+  void Execute(PolyTree &solution, double delta);
+
+  void Clear();
+
+  double MiterLimit;
+  double ArcTolerance;
+
+private:
+  Paths m_destPolys;
+  Path m_srcPoly;
+  Path m_destPoly;
+  std::vector<DoublePoint> m_normals;
+  double m_delta, m_sinA, m_sin, m_cos;
+  double m_miterLim, m_StepsPerRad;
+  IntPoint m_lowest;
+  PolyNode m_polyNodes;
+
+  void FixOrientations();
+
+  void DoOffset(double delta);
+
+  void OffsetPoint(int j, int &k, JoinType jointype);
+
+  void DoSquare(int j, int k);
+
+  void DoMiter(int j, int k, double r);
+
+  void DoRound(int j, int k);
+};
+//------------------------------------------------------------------------------
+
+class clipperException : public std::exception {
+public:
+  clipperException(const char *description) : m_descr(description) {}
+
+  virtual ~clipperException() throw() {}
+
+  virtual const char *what() const throw() { return m_descr.c_str(); }
+
+private:
+  std::string m_descr;
+};
+//------------------------------------------------------------------------------
+
+} // ClipperLib namespace
+
+#endif // clipper_hpp

deploy/android_demo/app/src/main/cpp/ocr_cls_process.cpp

+// Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "ocr_cls_process.h"
+#include <cmath>
+#include <cstring>
+#include <fstream>
+#include <iostream>
+#include <iostream>
+#include <vector>
+
+const std::vector<int> CLS_IMAGE_SHAPE = {3, 48, 192};
+
+cv::Mat cls_resize_img(const cv::Mat &img) {
+  int imgC = CLS_IMAGE_SHAPE[0];
+  int imgW = CLS_IMAGE_SHAPE[2];
+  int imgH = CLS_IMAGE_SHAPE[1];
+
+  float ratio = float(img.cols) / float(img.rows);
+  int resize_w = 0;
+  if (ceilf(imgH * ratio) > imgW)
+    resize_w = imgW;
+  else
+    resize_w = int(ceilf(imgH * ratio));
+
+  cv::Mat resize_img;
+  cv::resize(img, resize_img, cv::Size(resize_w, imgH), 0.f, 0.f,
+             cv::INTER_CUBIC);
+
+  if (resize_w < imgW) {
+    cv::copyMakeBorder(resize_img, resize_img, 0, 0, 0, int(imgW - resize_w),
+                       cv::BORDER_CONSTANT, {0, 0, 0});
+  }
+  return resize_img;
+}
\ No newline at end of file

deploy/android_demo/app/src/main/cpp/ocr_cls_process.h

+// Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#pragma once
+
+#include "common.h"
+#include <opencv2/opencv.hpp>
+#include <vector>
+
+extern const std::vector<int> CLS_IMAGE_SHAPE;
+
+cv::Mat cls_resize_img(const cv::Mat &img);
\ No newline at end of file