store SkAlphaType inside SkBitmap, on road to support unpremul

src/image/SkSurface_Gpu.cpp

Index: src/image/SkSurface_Gpu.cpp
diff --git a/src/image/SkSurface_Gpu.cpp b/src/image/SkSurface_Gpu.cpp
index e5b7bd4486a86d87e0f91b28db5389448671c3c9..7b3a6437d98328a01215bb27e16c7e107607262d 100644
--- a/src/image/SkSurface_Gpu.cpp
+++ b/src/image/SkSurface_Gpu.cpp
@@ -38,12 +38,11 @@ SK_DEFINE_INST_COUNT(SkSurface_Gpu)
 SkSurface_Gpu::SkSurface_Gpu(GrContext* ctx, const SkImage::Info& info,
                              int sampleCount)
         : INHERITED(info.fWidth, info.fHeight) {
-    bool isOpaque;
-    SkBitmap::Config config = SkImageInfoToBitmapConfig(info, &isOpaque);
+    SkBitmap::Config config = SkImageInfoToBitmapConfig(info);
 
     fDevice = SkNEW_ARGS(SkGpuDevice, (ctx, config, info.fWidth, info.fHeight, sampleCount));
 
-    if (!isOpaque) {
+    if (!SkAlphaTypeIsOpaque(info.fAlphaType)) {
         fDevice->clear(0x0);

[scroggo, 2013/10/18 21:52:41]

Not needed for this CL, obviously, but is this a candidate for calloc?

[reed1, 2013/10/21 12:24:25]

The clear() turns into a GPU command, and does not write memory (at least from
calloc's perspective). However, it is worth asking brian if we can skip this by
somehow allocating the rendertarget/texture to be automatically zero'd...

[bsalomon, 2013/10/21 13:18:04]

Not that I know of. On some OSes newly created textures are zeroed, but we can't
assume it generally.

     }
 }
@@ -119,8 +118,7 @@ SkSurface* SkSurface::NewRenderTarget(GrContext* ctx, const SkImage::Info& info,
         return NULL;
     }
 
-    bool isOpaque;
-    SkBitmap::Config config = SkImageInfoToBitmapConfig(info, &isOpaque);
+    SkBitmap::Config config = SkImageInfoToBitmapConfig(info);
 
     GrTextureDesc desc;
     desc.fFlags = kRenderTarget_GrTextureFlagBit | kCheckAllocation_GrTextureFlagBit;
@@ -136,3 +134,4 @@ SkSurface* SkSurface::NewRenderTarget(GrContext* ctx, const SkImage::Info& info,
 
     return SkNEW_ARGS(SkSurface_Gpu, (ctx, tex->asRenderTarget()));
 }
+