Add ContextRec param to SkShader::contextSize()

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)
+        ContextRec(const SkPaint& paint, const SkMatrix& matrix, const SkMatrix* localM,
+                   SkColorType devColorType, SkColorProfileType devColorProfile)
             : fPaint(&paint)
             , fMatrix(&matrix)
-            , fLocalMatrix(localM) {}
+            , fLocalMatrix(localM)
+            , fDeviceColorType(devColorType)
+            , fDeviceColorProfile(devColorProfile) {}
 
         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 SkColorType        fDeviceColorType;
+        const SkColorProfileType fDeviceColorProfile;

[f(malita), 2016/02/22 16:09:50]

I'm kinda torn on pushing explicit dst color info to the shaders - it means
they'll likely end up duplicating some of SkBlitter's heuristics in deciding
whether to optimize for 4b or 4f.

SkBlitter should know which shadeSpan method is going to use, so maybe a more
assertive

bool fWillCallShadeSpan4f;

would provide less footgun?

[f(malita), 2016/02/22 17:08:23]

PS#2 implements this alternative approach, replacing the color info with a
preferred-dst-type computed in SkBlitter.

PTAL

     };
 
     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 64 matching lines @@
      *  Size of storage must be >= contextSize.
      */
     Context* createContext(const ContextRec&, void* storage) const;
 
     /**
      *  Return the size of a Context returned by createContext.
      *
      *  Override this if your subclass overrides createContext, to return the correct size of
      *  your subclass' context.
      */
-    virtual size_t contextSize() const;
+    virtual size_t contextSize(const ContextRec&) const;
 
     /**
      *  Returns true if this shader is just a bitmap, and if not null, returns the bitmap,
      *  localMatrix, and tilemodes. If this is not a bitmap, returns false and ignores the
      *  out-parameters.
      */
     bool isABitmap(SkBitmap* outTexture, SkMatrix* outMatrix, TileMode xy[2]) const {
         return this->onIsABitmap(outTexture, outMatrix, xy);
     }
 
@@ skipping 224 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