Add alphaType() to SkImage

src/image/SkImage.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmap.h"
 #include "SkBitmapCache.h"
 #include "SkCanvas.h"
@@ skipping 88 matching lines @@
     //
     SkBitmap bm;
     if (as_IB(this)->getROPixels(&bm)) {
         bm.lockPixels();
         bm.unlockPixels();
     }
 }
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 
+SkAlphaType SkImage::alphaType() const {
+    return as_IB(this)->onAlphaType();
+}
+
 sk_sp<SkShader> SkImage::makeShader(SkShader::TileMode tileX, SkShader::TileMode tileY,
                                     const SkMatrix* localMatrix) const {
     return SkImageShader::Make(sk_ref_sp(const_cast<SkImage*>(this)), tileX, tileY, localMatrix);
 }
 
 #ifdef SK_SUPPORT_LEGACY_CREATESHADER_PTR
 SkShader* SkImage::newShader(SkShader::TileMode tileX, SkShader::TileMode tileY,
                              const SkMatrix* localMatrix) const {
     return this->makeShader(tileX, tileY, localMatrix).release();
 }
@@ skipping 194 matching lines @@
 }
 
 bool SkImage::asLegacyBitmap(SkBitmap* bitmap, LegacyBitmapMode mode) const {
     return as_IB(this)->onAsLegacyBitmap(bitmap, mode);
 }
 
 bool SkImage_Base::onAsLegacyBitmap(SkBitmap* bitmap, LegacyBitmapMode mode) const {
     // As the base-class, all we can do is make a copy (regardless of mode).
     // Subclasses that want to be more optimal should override.
     SkImageInfo info = this->onImageInfo().makeColorType(kN32_SkColorType)
-            .makeAlphaType(this->isOpaque() ? kOpaque_SkAlphaType : kPremul_SkAlphaType);
+            .makeAlphaType(this->alphaType());
     if (!bitmap->tryAllocPixels(info)) {
         return false;
     }
     if (!this->readPixels(bitmap->info(), bitmap->getPixels(), bitmap->rowBytes(), 0, 0)) {
         bitmap->reset();
         return false;
     }
 
     if (kRO_LegacyBitmapMode == mode) {
         bitmap->setImmutable();
@@ skipping 184 matching lines @@
     SkASSERT(image);
     SkASSERT(ctx);
     as_IB(image)->onPinAsTexture(ctx);
 }
 
 void SkImage_unpinAsTexture(const SkImage* image, GrContext* ctx) {
     SkASSERT(image);
     SkASSERT(ctx);
     as_IB(image)->onUnpinAsTexture(ctx);
 }