store SkAlphaType inside SkBitmap, on road to support unpremul

samplecode/SampleDitherBitmap.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 "SampleCode.h"
 #include "SkColorPriv.h"
 #include "SkGradientShader.h"
@@ skipping 83 matching lines @@
     virtual bool onQuery(SkEvent* evt) {
         if (SampleCode::TitleQ(*evt)) {
             SampleCode::TitleR(evt, "DitherBitmap");
             return true;
         }
         return this->INHERITED::onQuery(evt);
     }
 
     static void setBitmapOpaque(SkBitmap* bm, bool isOpaque) {
         SkAutoLockPixels alp(*bm);  // needed for ctable
-        bm->setIsOpaque(isOpaque);
+        bm->setAlphaType(isOpaque ? kOpaque_SkAlphaType : kPremul_SkAlphaType);
         SkColorTable* ctable = bm->getColorTable();
         if (ctable) {
             ctable->setIsOpaque(isOpaque);
         }
     }
 
     static void draw2(SkCanvas* canvas, const SkBitmap& bm) {
         SkPaint paint;
         SkBitmap bitmap(bm);
 
@@ skipping 23 matching lines @@
     }
 
 private:
     typedef SampleView INHERITED;
 };
 
 //////////////////////////////////////////////////////////////////////////////
 
 static SkView* MyFactory() { return new DitherBitmapView; }
 static SkViewRegister reg(MyFactory);