loaders: decode the image with premultiplied alpha.

basically, the renderer requires images with premultiplied alpha.

src/loaders/external_png/tvgPngLoader.cpp

@@ -104,6 +104,7 @@ bool PngLoader::read()
     surface.h = (uint32_t)h;
     surface.channelSize = sizeof(uint32_t);
     surface.cs = ColorSpace::ARGB8888;
+    //TODO: we can acquire a pre-multiplied image. See "png_structrp"
     surface.premultiplied = false;
 
     clear();

src/loaders/external_webp/tvgWebpLoader.cpp

@@ -33,9 +33,8 @@
 
 void WebpLoader::run(unsigned tid)
 {
+    //TODO: acquire the current colorspace format & pre-multiplied alpha image.
     surface.buf8 = WebPDecodeBGRA(data, size, nullptr, nullptr);
-
-    //setup the surface
     surface.stride = (uint32_t)w;
     surface.w = (uint32_t)w;
     surface.h = (uint32_t)h;

src/loaders/png/tvgPngLoader.cpp

@@ -44,7 +44,9 @@ void PngLoader::run(unsigned tid)
     surface.w = width;
     surface.h = height;
     surface.channelSize = sizeof(uint32_t);
-    surface.premultiplied = false;
+
+    if (state.info_png.color.colortype == LCT_RGBA) surface.premultiplied = false;
+    else surface.premultiplied = true;
 }
 
 

src/loaders/webp/dec/webp.cpp

@@ -651,7 +651,7 @@ int WebPIoInitFromOptions(const WebPDecoderOptions* const options,
 
 uint8_t* WebPDecodeBGRA(const uint8_t* data, size_t data_size,
                         int* width, int* height) {
-  return Decode(MODE_BGRA, data, data_size, width, height, NULL);
+  return Decode(MODE_bgrA, data, data_size, width, height, NULL);
 }
 
 

src/loaders/webp/tvgWebpLoader.cpp

@@ -42,7 +42,7 @@ void WebpLoader::run(unsigned tid)
     surface.h = static_cast<uint32_t>(h);
     surface.cs = ColorSpace::ARGB8888;
     surface.channelSize = sizeof(uint32_t);
-    surface.premultiplied = false;
+    surface.premultiplied = true;
 
     clear();
 }