store SkAlphaType inside SkBitmap, on road to support unpremul

src/ports/SkImageDecoder_WIC.cpp

 
 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkTypes.h"
 
@@ skipping 222 matching lines @@
         bm->eraseColor(SK_ColorTRANSPARENT);
         const UINT stride = (UINT) bm->rowBytes();
         hr = piBitmapSourceConverted->CopyPixels(
             NULL,                             //Get all the pixels
             stride,
             stride * height,
             reinterpret_cast<BYTE *>(bm->getPixels())
         );
 
         // Note: we don't need to premultiply here since we specified PBGRA
-        bm->computeAndSetOpaquePredicate();
+        if (ComputeIsOpaque(*bm)) {
+            bm->setAlphaType(kOpaque_SkAlphaType);
+        }
     }
 
     return SUCCEEDED(hr);
 }
 
 /////////////////////////////////////////////////////////////////////////
 
 extern SkImageDecoder* image_decoder_from_stream(SkStreamRewindable*);
 
 SkImageDecoder* SkImageDecoder::Factory(SkStreamRewindable* stream) {
@@ skipping 199 matching lines @@
 static SkImageDecoder::Format get_format_wic(SkStreamRewindable* stream) {
     SkImageDecoder::Format format;
     SkImageDecoder_WIC codec;
     if (!codec.decodeStream(stream, NULL, SkImageDecoder_WIC::kDecodeFormat_WICMode, &format)) {
         format = SkImageDecoder::kUnknown_Format;
     }
     return format;
 }
 
 static SkImageDecoder_FormatReg gFormatReg(get_format_wic);