Merge "examples: (windows/WIC) add alpha support"

examples/cwebp.c

@@ -44,6 +44,10 @@
 DEFINE_GUID(GUID_WICPixelFormat24bppRGB,
     0x6fddc324, 0x4e03, 0x4bfe, 0xb1, 0x85, 0x3d, 0x77, 0x76, 0x8d, 0xc9, 0x0d);
 #endif
+#ifndef GUID_WICPixelFormat32bppRGBA
+DEFINE_GUID(GUID_WICPixelFormat32bppRGBA,
+    0xf5c7ad2d, 0x6a8d, 0x43dd, 0xa7, 0xa8, 0xa2, 0x99, 0x35, 0x26, 0x1a, 0xe9);
+#endif
 #endif  /* HAVE_WINCODEC_H */
 
 
@@ -109,7 +113,7 @@ static HRESULT OpenInputStream(const char* filename, IStream** ppStream) {
 }
 
 static HRESULT ReadPictureWithWIC(const char* filename,
-                                  WebPPicture* const pic) {
+                                  WebPPicture* const pic, int keep_alpha) {
   HRESULT hr = S_OK;
   IWICBitmapFrameDecode* pFrame = NULL;
   IWICFormatConverter* pConverter = NULL;
@@ -119,6 +123,15 @@ static HRESULT ReadPictureWithWIC(const char* filename,
   UINT frameCount = 0;
   UINT width, height = 0;
   BYTE* rgb = NULL;
+  WICPixelFormatGUID srcPixelFormat = { 0 };
+  GUID srcContainerFormat = { 0 };
+  const GUID* alphaContainers[] = {
+    &GUID_ContainerFormatBmp,
+    &GUID_ContainerFormatPng,
+    &GUID_ContainerFormatTiff
+  };
+  int has_alpha = 0;
+  int i, stride;
 
   IFS(CoInitialize(NULL));
   IFS(CoCreateInstance(MAKE_REFGUID(CLSID_WICImagingFactory), NULL,
@@ -139,28 +152,53 @@ static HRESULT ReadPictureWithWIC(const char* filename,
     hr = E_FAIL;
   }
   IFS(IWICBitmapDecoder_GetFrame(pDecoder, 0, &pFrame));
+  IFS(IWICBitmapFrameDecode_GetPixelFormat(pFrame, &srcPixelFormat));
+  IFS(IWICBitmapDecoder_GetContainerFormat(pDecoder, &srcContainerFormat));
+
+  has_alpha = keep_alpha;
+  for (i = 0;
+       has_alpha && i < sizeof(alphaContainers)/sizeof(alphaContainers[0]);
+       ++i) {
+    if (IsEqualGUID(&srcContainerFormat, alphaContainers[i])) {
+      has_alpha =
+          IsEqualGUID(&srcPixelFormat, &GUID_WICPixelFormat32bppRGBA) ||
+          IsEqualGUID(&srcPixelFormat, &GUID_WICPixelFormat32bppBGRA);
+      break;
+    }
+  }
 
   // Prepare for pixel format conversion (if necessary).
   IFS(IWICImagingFactory_CreateFormatConverter(pFactory, &pConverter));
   IFS(IWICFormatConverter_Initialize(pConverter, (IWICBitmapSource*)pFrame,
-          MAKE_REFGUID(GUID_WICPixelFormat24bppRGB), WICBitmapDitherTypeNone,
+          has_alpha ? MAKE_REFGUID(GUID_WICPixelFormat32bppRGBA)
+                    : MAKE_REFGUID(GUID_WICPixelFormat24bppRGB),
+          WICBitmapDitherTypeNone,
           NULL, 0.0, WICBitmapPaletteTypeCustom));
 
   // Decode.
   IFS(IWICFormatConverter_GetSize(pConverter, &width, &height));
+  stride = (has_alpha ? 4 : 3) * width * sizeof(*rgb);
   if (SUCCEEDED(hr)) {
-    rgb = (BYTE*)malloc(3 * width * height);
+    rgb = (BYTE*)malloc(stride * height);
     if (rgb == NULL)
       hr = E_OUTOFMEMORY;
   }
-  IFS(IWICFormatConverter_CopyPixels(pConverter, NULL, 3 * width,
-          3 * width * height, rgb));
+  IFS(IWICFormatConverter_CopyPixels(pConverter, NULL, stride,
+          stride * height, rgb));
 
   // WebP conversion.
   if (SUCCEEDED(hr)) {
+    int ok;
+#ifdef WEBP_EXPERIMENTAL_FEATURES
+    if (has_alpha) {
+      pic->colorspace |= WEBP_CSP_ALPHA_BIT;
+    }
+#endif
     pic->width = width;
     pic->height = height;
-    if (!WebPPictureImportRGB(pic, rgb, 3 * width))
+    ok = has_alpha ? WebPPictureImportRGBA(pic, rgb, stride)
+                   : WebPPictureImportRGB(pic, rgb, stride);
+    if (!ok)
       hr = E_FAIL;
   }
 
@@ -188,7 +226,7 @@ static int ReadPicture(const char* const filename, WebPPicture* const pic,
     fclose(in_file);
   } else {
     // If no size specified, try to decode it using WIC.
-    ok = SUCCEEDED(ReadPictureWithWIC(filename, pic));
+    ok = SUCCEEDED(ReadPictureWithWIC(filename, pic, keep_alpha));
   }
   if (!ok) {
     fprintf(stderr, "Error! Could not process file %s\n", filename);

examples/dwebp.c

@@ -86,13 +86,14 @@ static HRESULT CreateOutputStream(const char* out_file_name,
 
 static HRESULT WriteUsingWIC(const char* out_file_name, REFGUID container_guid,
                              unsigned char* rgb, int stride,
-                             uint32_t width, uint32_t height) {
+                             uint32_t width, uint32_t height, int has_alpha) {
   HRESULT hr = S_OK;
   IWICImagingFactory* pFactory = NULL;
   IWICBitmapFrameEncode* pFrame = NULL;
   IWICBitmapEncoder* pEncoder = NULL;
   IStream* pStream = NULL;
-  GUID pixel_format = GUID_WICPixelFormat24bppBGR;
+  WICPixelFormatGUID pixel_format = has_alpha ? GUID_WICPixelFormat32bppBGRA
+                                              : GUID_WICPixelFormat24bppBGR;
 
   IFS(CoInitialize(NULL));
   IFS(CoCreateInstance(MAKE_REFGUID(CLSID_WICImagingFactory), NULL,
@@ -130,11 +131,11 @@ static int WritePNG(const char* out_file_name,
   const uint32_t height = buffer->height;
   unsigned char* const rgb = buffer->u.RGBA.rgba;
   const int stride = buffer->u.RGBA.stride;
-  const int has_alpha = (buffer->colorspace == MODE_RGBA);
-  assert(!has_alpha);   // TODO(mikolaj)
+  const int has_alpha = (buffer->colorspace == MODE_BGRA);
+
   return SUCCEEDED(WriteUsingWIC(out_file_name,
              MAKE_REFGUID(GUID_ContainerFormatPng), rgb, stride, width,
-             height));
+             height, has_alpha));
 }
 
 #elif defined(WEBP_HAVE_PNG)    // !HAVE_WINCODEC_H
@@ -266,7 +267,7 @@ static void SaveOutput(const WebPDecBuffer* const buffer,
   if (verbose)
     StopwatchReadAndReset(&stop_watch);
 
-#ifdef _WIN32
+#ifdef HAVE_WINCODEC_H
   needs_open_file = (format != PNG);
 #endif
   if (needs_open_file) {
@@ -431,9 +432,8 @@ int main(int argc, const char *argv[]) {
 
     switch (format) {
       case PNG:
-#ifdef _WIN32
-        // TODO(mikolaj): no alpha for now
-        output_buffer->colorspace = MODE_BGR;
+#ifdef HAVE_WINCODEC_H
+        output_buffer->colorspace = bitstream->has_alpha ? MODE_BGRA : MODE_BGR;
 #else
         output_buffer->colorspace = bitstream->has_alpha ? MODE_RGBA : MODE_RGB;
 #endif