Changed code around so that the save_png.h header file doesn't need to #include png.h.

I did this because png.h will cause the compile to fail if the user #includes setjmp.h
along with png.h.

dlib/all/source.cpp

@@ -47,6 +47,7 @@
 
 #ifdef DLIB_PNG_SUPPORT
 #include "../image_loader/png_loader.cpp"
+#include "../image_saver/save_png.cpp"
 #endif
 
 #ifdef DLIB_JPEG_SUPPORT

dlib/image_saver/save_png.cpp

+// Copyright (C) 2011  Davis E. King (davis@dlib.net)
+// License: Boost Software License   See LICENSE.txt for the full license.
+#ifndef DLIB_SAVE_PnG_CPP__
+#define DLIB_SAVE_PnG_CPP__
+
+// only do anything with this file if DLIB_PNG_SUPPORT is defined
+#ifdef DLIB_PNG_SUPPORT
+
+#include "save_png.h"
+#include <cstdio>
+#include <png.h>
+
+namespace dlib
+{
+    // Don't do anything when libpng calls us to tell us about an error.  Just return to 
+    // our own code and throw an exception (at the long jump target).
+    void png_reader_user_error_fn_silent(png_structp  png_struct, png_const_charp ) 
+    {
+        longjmp(png_jmpbuf(png_struct),1);
+    }
+    void png_reader_user_warning_fn_silent(png_structp , png_const_charp ) 
+    {
+    }
+
+    namespace impl
+    {
+        void impl_save_png (
+            const std::string& file_name,
+            std::vector<unsigned char*>& row_pointers,
+            const long width,
+            const png_type type,
+            const int bit_depth
+        )
+        {
+
+            FILE *fp;
+            png_structp png_ptr;
+            png_infop info_ptr;
+
+            /* Open the file */
+            fp = fopen(file_name.c_str(), "wb");
+            if (fp == NULL)
+                throw image_save_error("Unable to open " + file_name + " for writing.");
+
+            /* Create and initialize the png_struct with the desired error handler
+            * functions.  If you want to use the default stderr and longjump method,
+            * you can supply NULL for the last three parameters.  We also check that
+            * the library version is compatible with the one used at compile time,
+            * in case we are using dynamically linked libraries.  REQUIRED.
+            */
+            png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, &png_reader_user_error_fn_silent, &png_reader_user_warning_fn_silent);
+
+            if (png_ptr == NULL)
+            {
+                fclose(fp);
+                throw image_save_error("Error while writing PNG file " + file_name);
+            }
+
+            /* Allocate/initialize the image information data.  REQUIRED */
+            info_ptr = png_create_info_struct(png_ptr);
+            if (info_ptr == NULL)
+            {
+                fclose(fp);
+                png_destroy_write_struct(&png_ptr,  NULL);
+                throw image_save_error("Error while writing PNG file " + file_name);
+            }
+
+            /* Set error handling.  REQUIRED if you aren't supplying your own
+            * error handling functions in the png_create_write_struct() call.
+            */
+            if (setjmp(png_jmpbuf(png_ptr)))
+            {
+                /* If we get here, we had a problem writing the file */
+                fclose(fp);
+                png_destroy_write_struct(&png_ptr, &info_ptr);
+                throw image_save_error("Error while writing PNG file " + file_name);
+            }
+
+            int color_type = 0;
+            switch(type)
+            {
+                case png_type_rgb:       color_type = PNG_COLOR_TYPE_RGB; break;
+                case png_type_rgb_alpha: color_type = PNG_COLOR_TYPE_RGB_ALPHA; break;
+                case png_type_gray:      color_type = PNG_COLOR_TYPE_GRAY; break;
+                default:
+                    {
+                        fclose(fp);
+                        png_destroy_write_struct(&png_ptr, &info_ptr);
+                        throw image_save_error("Invalid color type");
+                    }
+            }
+
+
+            /* Set up the output control if you are using standard C streams */
+            png_init_io(png_ptr, fp);
+
+
+            const int png_transforms = PNG_TRANSFORM_IDENTITY;
+            const long height = row_pointers.size();
+
+
+            png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, color_type, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
+            png_set_rows(png_ptr, info_ptr, &row_pointers[0]);
+            png_write_png(png_ptr, info_ptr, png_transforms, NULL);
+
+            /* Clean up after the write, and free any memory allocated */
+            png_destroy_write_struct(&png_ptr, &info_ptr);
+
+            /* Close the file */
+            fclose(fp);
+        }
+    }
+}
+
+#endif // DLIB_PNG_SUPPORT
+
+#endif // DLIB_SAVE_PnG_CPP__
+
+

dlib/image_saver/save_png.h

@@ -5,30 +5,35 @@
 
 #include "save_png_abstract.h"
 #include "image_saver.h"
-#include "dlib/array2d.h"
-#include "dlib/pixel.h"
-#include <cstdio>
+#include "../array2d.h"
 #include <vector>
 #include <string>
 #include "../pixel.h"
 
-#ifdef DLIB_PNG_SUPPORT
-#include <png.h>
-#endif
-
 namespace dlib
 {
-#ifdef DLIB_PNG_SUPPORT
-    // Don't do anything when libpng calls us to tell us about an error.  Just return to 
-    // our own code and throw an exception (at the long jump target).
-    inline void png_reader_user_error_fn_silent(png_structp  png_struct, png_const_charp ) 
-    {
-        longjmp(png_jmpbuf(png_struct),1);
-    }
-    inline void png_reader_user_warning_fn_silent(png_structp , png_const_charp ) 
+
+// ----------------------------------------------------------------------------------------
+
+    namespace impl
     {
+        enum png_type
+        {
+            png_type_rgb,
+            png_type_rgb_alpha,
+            png_type_gray,
+        };
+
+        void impl_save_png (
+            const std::string& file_name,
+            std::vector<unsigned char*>& row_pointers,
+            const long width,
+            const png_type type,
+            const int bit_depth
+        );
     }
-#endif
+
+// ----------------------------------------------------------------------------------------
 
     template <
         typename image_type
@@ -39,7 +44,7 @@ namespace dlib
     )
     {
         // make sure requires clause is not broken
-        DLIB_ASSERT(img.size() != 0,
+        DLIB_CASSERT(img.size() != 0,
             "\t save_png()"
             << "\n\t You can't save an empty image as a PNG"
             );
@@ -54,125 +59,42 @@ namespace dlib
             !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!*/
             COMPILE_TIME_ASSERT(sizeof(image_type) == 0);
 #else
-        std::vector<png_byte*> row_pointers(img.nr());
-        FILE *fp;
-        png_structp png_ptr;
-        png_infop info_ptr;
-
-        /* Open the file */
-        fp = fopen(file_name.c_str(), "wb");
-        if (fp == NULL)
-            throw image_save_error("Unable to open " + file_name + " for writing.");
-
-        /* Create and initialize the png_struct with the desired error handler
-         * functions.  If you want to use the default stderr and longjump method,
-         * you can supply NULL for the last three parameters.  We also check that
-         * the library version is compatible with the one used at compile time,
-         * in case we are using dynamically linked libraries.  REQUIRED.
-        */
-        png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, &png_reader_user_error_fn_silent, &png_reader_user_warning_fn_silent);
-
-        if (png_ptr == NULL)
-        {
-            fclose(fp);
-            throw image_save_error("Error while writing PNG file " + file_name);
-        }
-
-        /* Allocate/initialize the image information data.  REQUIRED */
-        info_ptr = png_create_info_struct(png_ptr);
-        if (info_ptr == NULL)
-        {
-            fclose(fp);
-            png_destroy_write_struct(&png_ptr,  NULL);
-            throw image_save_error("Error while writing PNG file " + file_name);
-        }
-
-        /* Set error handling.  REQUIRED if you aren't supplying your own
-         * error handling functions in the png_create_write_struct() call.
-        */
-        if (setjmp(png_jmpbuf(png_ptr)))
-        {
-            /* If we get here, we had a problem writing the file */
-            fclose(fp);
-            png_destroy_write_struct(&png_ptr, &info_ptr);
-            throw image_save_error("Error while writing PNG file " + file_name);
-        }
-
-
-        /* Set up the output control if you are using standard C streams */
-        png_init_io(png_ptr, fp);
-
-
-        const int png_transforms = PNG_TRANSFORM_IDENTITY;
-        const long width = img.nc();
-        const long height = img.nr();
+        std::vector<unsigned char*> row_pointers(img.nr());
         typedef typename image_type::type pixel_type;
 
         if (is_same_type<rgb_pixel,pixel_type>::value)
         {
-            const int bit_depth = 8;
-            int color_type = PNG_COLOR_TYPE_RGB;
-            png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, color_type, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
             for (unsigned long i = 0; i < row_pointers.size(); ++i)
-                row_pointers[i] = (png_byte*)(&img[i][0]);
-            png_set_rows(png_ptr, info_ptr, &row_pointers[0]);
-            png_write_png(png_ptr, info_ptr, png_transforms, NULL);
+                row_pointers[i] = (unsigned char*)(&img[i][0]);
+
+            impl::impl_save_png(file_name, row_pointers, img.nc(), impl::png_type_rgb, 8);
         }
         else if (is_same_type<rgb_alpha_pixel,pixel_type>::value)
         {
-            const int bit_depth = 8;
-            int color_type = PNG_COLOR_TYPE_RGB_ALPHA;
-            png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, color_type, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
             for (unsigned long i = 0; i < row_pointers.size(); ++i)
-                row_pointers[i] = (png_byte*)(&img[i][0]);
-            png_set_rows(png_ptr, info_ptr, &row_pointers[0]);
-            png_write_png(png_ptr, info_ptr, png_transforms, NULL);
+                row_pointers[i] = (unsigned char*)(&img[i][0]);
+
+            impl::impl_save_png(file_name, row_pointers, img.nc(), impl::png_type_rgb_alpha, 8);
         }
         else if (pixel_traits<pixel_type>::hsi || pixel_traits<pixel_type>::rgb)
         {
-            try
-            {
-                // convert from HSI to RGB (Or potentially RGB pixels that aren't laid out as R G B)
-                array2d<rgb_pixel> temp_img;
-                assign_image(temp_img, img);
+            // convert from HSI to RGB (Or potentially RGB pixels that aren't laid out as R G B)
+            array2d<rgb_pixel> temp_img;
+            assign_image(temp_img, img);
+            for (unsigned long i = 0; i < row_pointers.size(); ++i)
+                row_pointers[i] = (unsigned char*)(&temp_img[i][0]);
 
-                const int bit_depth = 8;
-                int color_type = PNG_COLOR_TYPE_RGB;
-                png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, color_type, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
-                for (unsigned long i = 0; i < row_pointers.size(); ++i)
-                    row_pointers[i] = (png_byte*)(&temp_img[i][0]);
-                png_set_rows(png_ptr, info_ptr, &row_pointers[0]);
-                png_write_png(png_ptr, info_ptr, png_transforms, NULL);
-            }
-            catch (...)
-            {
-                fclose(fp);
-                png_destroy_write_struct(&png_ptr, &info_ptr);
-                throw;
-            }
+            impl::impl_save_png(file_name, row_pointers, img.nc(), impl::png_type_rgb, 8);
         }
         else if (pixel_traits<pixel_type>::rgb_alpha)
         {
-            try
-            {
-                // convert from RGBA pixels that aren't laid out as R G B A
-                array2d<rgb_alpha_pixel> temp_img;
-                assign_image(temp_img, img);
+            // convert from RGBA pixels that aren't laid out as R G B A
+            array2d<rgb_alpha_pixel> temp_img;
+            assign_image(temp_img, img);
+            for (unsigned long i = 0; i < row_pointers.size(); ++i)
+                row_pointers[i] = (unsigned char*)(&temp_img[i][0]);
 
-                const int bit_depth = 8;
-                int color_type = PNG_COLOR_TYPE_RGB_ALPHA;
-                png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, color_type, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
-                for (unsigned long i = 0; i < row_pointers.size(); ++i)
-                    row_pointers[i] = (png_byte*)(&temp_img[i][0]);
-                png_set_rows(png_ptr, info_ptr, &row_pointers[0]);
-                png_write_png(png_ptr, info_ptr, png_transforms, NULL);
-            }
-            catch (...)
-            {
-                fclose(fp);
-                png_destroy_write_struct(&png_ptr, &info_ptr);
-                throw;
-            }
+            impl::impl_save_png(file_name, row_pointers, img.nc(), impl::png_type_rgb_alpha, 8);
         }
         else // this is supposed to be grayscale 
         {
@@ -180,60 +102,39 @@ namespace dlib
 
             if (pixel_traits<pixel_type>::is_unsigned && sizeof(pixel_type) == 1)
             {
-                const int bit_depth = 8;
-                int color_type = PNG_COLOR_TYPE_GRAY;
-                png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, color_type, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
                 for (unsigned long i = 0; i < row_pointers.size(); ++i)
-                    row_pointers[i] = (png_byte*)(&img[i][0]);
-                png_set_rows(png_ptr, info_ptr, &row_pointers[0]);
-                png_write_png(png_ptr, info_ptr, png_transforms, NULL);
+                    row_pointers[i] = (unsigned char*)(&img[i][0]);
+
+                impl::impl_save_png(file_name, row_pointers, img.nc(), impl::png_type_gray, 8);
             }
             else if (pixel_traits<pixel_type>::is_unsigned && sizeof(pixel_type) == 2)
             {
-                const int bit_depth = 16;
-                int color_type = PNG_COLOR_TYPE_GRAY;
-                png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, color_type, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
                 for (unsigned long i = 0; i < row_pointers.size(); ++i)
-                    row_pointers[i] = (png_byte*)(&img[i][0]);
-                png_set_rows(png_ptr, info_ptr, &row_pointers[0]);
-                png_write_png(png_ptr, info_ptr, png_transforms, NULL);
+                    row_pointers[i] = (unsigned char*)(&img[i][0]);
+
+                impl::impl_save_png(file_name, row_pointers, img.nc(), impl::png_type_gray, 16);
             }
             else
             {
-                try
-                {
-                    // convert from whatever this is to 16bit grayscale 
-                    array2d<dlib::uint16> temp_img;
-                    assign_image(temp_img, img);
-
-                    const int bit_depth = 16;
-                    int color_type = PNG_COLOR_TYPE_GRAY;
-                    png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, color_type, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
-                    for (unsigned long i = 0; i < row_pointers.size(); ++i)
-                        row_pointers[i] = (png_byte*)(&temp_img[i][0]);
-                    png_set_rows(png_ptr, info_ptr, &row_pointers[0]);
-                    png_write_png(png_ptr, info_ptr, png_transforms, NULL);
-                }
-                catch (...)
-                {
-                    fclose(fp);
-                    png_destroy_write_struct(&png_ptr, &info_ptr);
-                    throw;
-                }
+                // convert from whatever this is to 16bit grayscale 
+                array2d<dlib::uint16> temp_img;
+                assign_image(temp_img, img);
+                for (unsigned long i = 0; i < row_pointers.size(); ++i)
+                    row_pointers[i] = (unsigned char*)(&temp_img[i][0]);
+
+                impl::impl_save_png(file_name, row_pointers, img.nc(), impl::png_type_gray, 16);
             }
         }
 
 
-
-        /* Clean up after the write, and free any memory allocated */
-        png_destroy_write_struct(&png_ptr, &info_ptr);
-
-        /* Close the file */
-        fclose(fp);
 #endif
 
     }
 }
 
+#ifdef NO_MAKEFILE
+#include "save_png.cpp"
+#endif
+
 #endif // DLIB_SAVE_PnG_H__