Add the ability to handle premul and swizzle src bitmap data.

src/core/SkBitmapProcShader.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 "SkBitmapProcShader.h"
 #include "SkBitmapProcState.h"
 #include "SkBitmapProvider.h"
@@ skipping 187 matching lines @@
     SkFilterQuality            fFilterQuality;
 
     typedef BitmapProcInfoContext INHERITED;
 };
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 
 static bool choose_linear_pipeline(const SkShader::ContextRec& rec, const SkImageInfo& srcInfo) {
     // If we get here, we can reasonably use either context, respect the caller's preference
     //
-    return SkShader::ContextRec::kPM4f_DstType == rec.fPreferredDstType;
+    bool needsPremul = srcInfo.alphaType() == kUnpremul_SkAlphaType;
+    bool needsSwizzle = srcInfo.bytesPerPixel() == 4 && srcInfo.colorType() != kN32_SkColorType;
+    return SkShader::ContextRec::kPM4f_DstType == rec.fPreferredDstType
+           || needsPremul || needsSwizzle;
 }
 
 size_t SkBitmapProcShader::ContextSize(const ContextRec& rec, const SkImageInfo& srcInfo) {
     size_t size0 = sizeof(BitmapProcShaderContext) + sizeof(SkBitmapProcState);
     size_t size1 = sizeof(LinearPipelineContext) + sizeof(SkBitmapProcInfo);
     return SkTMax(size0, size1);
 }
 
 SkShader::Context* SkBitmapProcShader::MakeContext(const SkShader& shader,
                                                    TileMode tmx, TileMode tmy,
@@ skipping 236 matching lines @@
         inner.reset(GrSimpleTextureEffect::Create(texture, matrix, params));
     }
 
     if (kAlpha_8_SkColorType == fRawBitmap.colorType()) {
         return GrFragmentProcessor::MulOutputByInputUnpremulColor(inner);
     }
     return GrFragmentProcessor::MulOutputByInputAlpha(inner);
 }
 
 #endif