optimize case where image_view is used but is not a subset - refs #2024

include/mapnik/webp_io.hpp

@@ -73,9 +73,30 @@ inline int import_image_data(T2 const& image,
                              WebPPicture & pic,
                              bool alpha)
 {
-    // Reason for copy: https://github.com/mapnik/mapnik/issues/2024
+    ImageData<typename T2::pixel_type> const& data = image.data();
+    int stride = sizeof(typename T2::pixel_type) * image.width();
+    if (data.width() == image.width() &&
+        data.height() == image.height())
+    {
+        std::clog << "opt\n";
+        if (alpha)
+        {
+            return WebPPictureImportRGBA(&pic, data.getBytes(), stride);
+        }
+        else
+        {
+    #if (WEBP_ENCODER_ABI_VERSION >> 8) >= 1
+            return WebPPictureImportRGBX(&pic, data.getBytes(), stride);
+    #else
+            return WebPPictureImportRGBA(&pic, data.getBytes(), stride);
+    #endif
+        }
+    }
+    else
+    {
+        // need to copy: https://github.com/mapnik/mapnik/issues/2024
+        std::clog << "copy\n";
         image_data_32 im(image.width(),image.height());
-    int stride = sizeof(typename T2::pixel_type) * im.width();
         for (unsigned y = 0; y < image.height(); ++y)
         {
             typename T2::pixel_type const * row_from = image.getRow(y);
@@ -95,6 +116,7 @@ inline int import_image_data(T2 const& image,
     #endif
         }
     }
+}
 
 template <>
 inline int import_image_data(image_data_32 const& im,