Add dest type hint to SkShader::ContextRec

include/core/SkShader.h

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkShader_DEFINED
 #define SkShader_DEFINED
 
 #include "SkBitmap.h"
 #include "SkFlattenable.h"
+#include "SkImageInfo.h"
 #include "SkMask.h"
 #include "SkMatrix.h"
 #include "SkPaint.h"
 #include "../gpu/GrColor.h"
 
 class SkColorFilter;
 class SkPath;
 class SkPicture;
 class SkXfermode;
 class GrContext;
@@ skipping 66 matching lines @@
      *  colors, subject to the SkPaint using the shader to apply an opaque
      *  alpha value. Subclasses should override this to allow some
      *  optimizations.
      */
     virtual bool isOpaque() const { return false; }
 
     /**
      *  ContextRec acts as a parameter bundle for creating Contexts.
      */
     struct ContextRec {
-        ContextRec(const SkPaint& paint, const SkMatrix& matrix, const SkMatrix* localM)
+        enum DstType {
+            kPMColor_DstType, // clients prefer shading into PMColor dest
+            kPM4f_DstType,    // clients prefer shading into PM4f dest
+        };
+
+        ContextRec(const SkPaint& paint, const SkMatrix& matrix, const SkMatrix* localM,
+                   DstType dstType)
             : fPaint(&paint)
             , fMatrix(&matrix)
-            , fLocalMatrix(localM) {}
+            , fLocalMatrix(localM)
+            , fPreferredDstType(dstType) {}
 
-        const SkPaint*  fPaint;         // the current paint associated with the draw
-        const SkMatrix* fMatrix;        // the current matrix in the canvas
-        const SkMatrix* fLocalMatrix;   // optional local matrix
+        const SkPaint*  fPaint;            // the current paint associated with the draw
+        const SkMatrix* fMatrix;           // the current matrix in the canvas
+        const SkMatrix* fLocalMatrix;      // optional local matrix
+        const DstType   fPreferredDstType; // the "natural" client dest type
     };
 
     class Context : public ::SkNoncopyable {
     public:
         Context(const SkShader& shader, const ContextRec&);
 
         virtual ~Context();
 
         /**
          *  Called sometimes before drawing with this shader. Return the type of
@@ skipping 309 matching lines @@
     SkMatrix fLocalMatrix;
 
     // So the SkLocalMatrixShader can whack fLocalMatrix in its SkReadBuffer constructor.
     friend class SkLocalMatrixShader;
     friend class SkBitmapProcShader;    // for computeTotalInverse()
 
     typedef SkFlattenable INHERITED;
 };
 
 #endif