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

src/effects/gradients/SkTwoPointConicalGradient.h

Index: src/effects/gradients/SkTwoPointConicalGradient.h
diff --git a/src/effects/gradients/SkTwoPointConicalGradient.h b/src/effects/gradients/SkTwoPointConicalGradient.h
index 20a3da8b2e82a5c6fae7ba3ff958d196a58d6060..b30ee70595e496ef32fc09a5f7e3493e60bafff1 100644
--- a/src/effects/gradients/SkTwoPointConicalGradient.h
+++ b/src/effects/gradients/SkTwoPointConicalGradient.h
@@ -11,6 +11,8 @@
 
 #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
@@ -27,16 +29,20 @@ struct TwoPtRadial {
     void init(const SkPoint& center0, SkScalar rad0,
               const SkPoint& center1, SkScalar rad1);
 
-    // used by setup and nextT
+    static bool DontDrawT(SkFixed t) {
+        return kDontDrawT == (uint32_t)t;
+    }
+};
+
+// Mutable part of TwoPtRadial.

[scroggo, 2014/04/02 20:16:53]

I find this comment confusing, since it's no longer a part of TwoPtRadial (it is
its own thing).

[Dominik Grewe, 2014/04/03 12:12:59]

Removed.

+struct TwoPtRadialContext {

[scroggo, 2014/04/02 20:16:53]

This should probably be moved to the cpp file.

[Dominik Grewe, 2014/04/03 12:12:59]

Done.

     float   fRelX, fRelY, fIncX, fIncY;
     float   fB, fDB;

[scroggo, 2014/04/02 20:16:53]

It appears that fIncX, fIncY, and fDB could be const?

[Dominik Grewe, 2014/04/03 12:12:59]

Done.

+    const TwoPtRadial& fRec;

[scroggo, 2014/04/02 20:16:53]

nit: the variable names should be aligned.

[Dominik Grewe, 2014/04/03 12:12:59]

Done.

 
-    void setup(SkScalar fx, SkScalar fy, SkScalar dfx, SkScalar dfy);
+    TwoPtRadialContext(const TwoPtRadial& rec, SkScalar fx, SkScalar fy,
+                          SkScalar dfx, SkScalar dfy);
     SkFixed nextT();
-
-    static bool DontDrawT(SkFixed t) {
-        return kDontDrawT == (uint32_t)t;
-    }
 };
 
 
@@ -49,11 +55,23 @@ public:
                               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,