store SkAlphaType inside SkBitmap, on road to support unpremul

src/images/SkImageDecoder_libwebp.cpp

 /*
  * Copyright 2010, The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
@@ skipping 275 matching lines @@
         if (config != SkBitmap::kRGB_565_Config &&
             config != SkBitmap::kARGB_4444_Config) {
             config = SkBitmap::kARGB_8888_Config;
         }
     }
 
     if (!this->chooseFromOneChoice(config, width, height)) {
         return false;
     }
 
-    decodedBitmap->setConfig(config, width, height, 0);
-
-    decodedBitmap->setIsOpaque(!fHasAlpha);
-
-    return true;
+    return decodedBitmap->setConfig(config, width, height, 0,
+                                    fHasAlpha ? kPremul_SkAlphaType : kOpaque_SkAlphaType);

[scroggo, 2013/09/30 22:20:04]

This should check this->getRequireUnpremultipliedColors()

 }
 
 bool SkWEBPImageDecoder::onBuildTileIndex(SkStreamRewindable* stream,
                                           int *width, int *height) {
     int origWidth, origHeight, hasAlpha;
     if (!webp_parse_header(stream, &origWidth, &origHeight, &hasAlpha)) {
         return false;
     }
 
     if (!stream->rewind()) {
@@ skipping 282 matching lines @@
     return SkImageDecoder::kUnknown_Format;
 }
 
 static SkImageEncoder* sk_libwebp_efactory(SkImageEncoder::Type t) {
       return (SkImageEncoder::kWEBP_Type == t) ? SkNEW(SkWEBPImageEncoder) : NULL;
 }
 
 static SkImageDecoder_DecodeReg gDReg(sk_libwebp_dfactory);
 static SkImageDecoder_FormatReg gFormatReg(get_format_webp);
 static SkImageEncoder_EncodeReg gEReg(sk_libwebp_efactory);