Made toMat() work with matrix object in addition to array2d style images.

dlib/opencv/to_open_cv.h

@@ -5,9 +5,13 @@
 
 #include "to_open_cv_abstract.h"
 #include "../pixel.h"
+#include "../matrix/matrix.h"
 
 namespace dlib
 {
+
+// ----------------------------------------------------------------------------------------
+
     template <
         typename image_type
         >
@@ -27,10 +31,42 @@ namespace dlib
         {
             int depth = sizeof(typename pixel_traits<type>::basic_pixel_type)*8;
             int channels = pixel_traits<type>::num;
-            int type = CV_MAKETYPE(depth, channels);
-            return cv::Mat(img.nr(), img.nc(), type, (void*)&img[0][0], img.width_step());
+            int thetype = CV_MAKETYPE(depth, channels);
+            return cv::Mat(img.nr(), img.nc(), thetype, (void*)&img[0][0], img.width_step());
         }
     }
+
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename T,
+        long NR,
+        long NC,
+        typename MM
+        >
+    cv::Mat toMat (
+        matrix<T,NR,NC,MM>& img
+    )
+    {
+        if (img.size() == 0)
+            return cv::Mat();
+
+        typedef T type;
+        if (pixel_traits<type>::num == 1)
+        {
+            return cv::Mat(img.nr(), img.nc(), cv::DataType<type>::type, (void*)&img(0,0), img.nc()*sizeof(type));
+        }
+        else
+        {
+            int depth = sizeof(typename pixel_traits<type>::basic_pixel_type)*8;
+            int channels = pixel_traits<type>::num;
+            int thetype = CV_MAKETYPE(depth, channels);
+            return cv::Mat(img.nr(), img.nc(), thetype, (void*)&img(0,0), img.nc()*sizeof(type));
+        }
+    }
+
+// ----------------------------------------------------------------------------------------
+
 }
 
 #endif // DLIB_TO_OPEN_Cv_H__

dlib/opencv/to_open_cv_abstract.h

@@ -15,7 +15,8 @@ namespace dlib
     );
     /*!
         requires
-            - image_type == an implementation of dlib/array2d/array2d_kernel_abstract.h
+            - image_type == an implementation of dlib/array2d/array2d_kernel_abstract.h or
+              a dlib::matrix object which uses a row_major_layout.
             - pixel_traits<typename image_type::type> is defined
         ensures
             - returns an OpenCV Mat object which represents the same image as img.  This