Extract most of the mutable state of SkShader into a separate Context object.

src/effects/gradients/SkTwoPointConicalGradient.h

 
 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
  #ifndef SkTwoPointConicalGradient_DEFINED
  #define SkTwoPointConicalGradient_DEFINED
 
 #include "SkGradientShaderPriv.h"
 
+// TODO(dominikg): Worth making it truly immutable (i.e. set values in constructor)?
+// Should only be initialized once via init(). Immutable afterwards.
 struct TwoPtRadial {
     enum {
         kDontDrawT  = 0x80000000
     };
 
     float   fCenterX, fCenterY;
     float   fDCenterX, fDCenterY;
     float   fRadius;
     float   fDRadius;
     float   fA;
     float   fRadius2;
     float   fRDR;
 
     void init(const SkPoint& center0, SkScalar rad0,
               const SkPoint& center1, SkScalar rad1);
 
-    // used by setup and nextT
-    float   fRelX, fRelY, fIncX, fIncY;
-    float   fB, fDB;
-
-    void setup(SkScalar fx, SkScalar fy, SkScalar dfx, SkScalar dfy);
-    SkFixed nextT();
-
     static bool DontDrawT(SkFixed t) {
         return kDontDrawT == (uint32_t)t;
     }
 };
 
 
 class SkTwoPointConicalGradient : public SkGradientShaderBase {
     TwoPtRadial fRec;
     void init();
 
 public:
     SkTwoPointConicalGradient(const SkPoint& start, SkScalar startRadius,
                               const SkPoint& end, SkScalar endRadius,
                               const Descriptor&);
 
-    virtual void shadeSpan(int x, int y, SkPMColor* dstCParam,
-                           int count) SK_OVERRIDE;
-    virtual bool setContext(const SkBitmap& device,
-                            const SkPaint& paint,
-                            const SkMatrix& matrix) SK_OVERRIDE;
+
+    virtual SkShader::Context* createContext(const SkBitmap&, const SkPaint&, const SkMatrix&,
+                                             void* storage) const SK_OVERRIDE;
+    virtual size_t contextSize() const SK_OVERRIDE;
+
+    class TwoPointConicalGradientContext : public SkGradientShaderBase::GradientShaderBaseContext {
+    public:
+        TwoPointConicalGradientContext(const SkTwoPointConicalGradient& shader,
+                                       const SkBitmap& device,
+                                       const SkPaint& paint,
+                                       const SkMatrix& matrix);
+        ~TwoPointConicalGradientContext() {}
+
+        virtual void shadeSpan(int x, int y, SkPMColor dstC[], int count) SK_OVERRIDE;
+
+        typedef SkGradientShaderBase::GradientShaderBaseContext INHERITED;
+    };
 
     virtual BitmapType asABitmap(SkBitmap* bitmap,
                                  SkMatrix* matrix,
                                  TileMode* xy) const;
     virtual SkShader::GradientType asAGradient(GradientInfo* info) const  SK_OVERRIDE;
     virtual GrEffectRef* asNewEffect(GrContext* context, const SkPaint& paint) const SK_OVERRIDE;
     virtual bool isOpaque() const SK_OVERRIDE;
 
     SkScalar getCenterX1() const { return SkPoint::Distance(fCenter1, fCenter2); }
     SkScalar getStartRadius() const { return fRadius1; }
     SkScalar getDiffRadius() const { return fRadius2 - fRadius1; }
 
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkTwoPointConicalGradient)
 
 protected:
     SkTwoPointConicalGradient(SkReadBuffer& buffer);
     virtual void flatten(SkWriteBuffer& buffer) const SK_OVERRIDE;
 
 private:
     typedef SkGradientShaderBase INHERITED;
     const SkPoint fCenter1;
     const SkPoint fCenter2;
     const SkScalar fRadius1;
     const SkScalar fRadius2;
 };
 
 #endif