create struct to hold all the params passed around for shader::context

src/core/SkDraw.cpp

 /*
  * 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.
  */
 
 #include "SkDraw.h"
 #include "SkBlitter.h"
 #include "SkBounder.h"
@@ skipping 2335 matching lines @@
     dst[0] = verts[state.f0];
     dst[1] = verts[state.f1];
     dst[2] = verts[state.f2];
     return matrix->setPolyToPoly(src, dst, 3);
 }
 
 class SkTriColorShader : public SkShader {
 public:
     SkTriColorShader() {}
 
-    virtual SkShader::Context* createContext(
-            const SkBitmap&, const SkPaint&, const SkMatrix&, void*) const SK_OVERRIDE;
+    virtual SkShader::Context* createContext(const ContextRec&, void*) const SK_OVERRIDE;
     virtual size_t contextSize() const SK_OVERRIDE;
 
     class TriColorShaderContext : public SkShader::Context {
     public:
-        TriColorShaderContext(const SkTriColorShader& shader, const SkBitmap& device,
-                              const SkPaint& paint, const SkMatrix& matrix);
+        TriColorShaderContext(const SkTriColorShader& shader, const ContextRec&);
         virtual ~TriColorShaderContext();
 
         bool setup(const SkPoint pts[], const SkColor colors[], int, int, int);
 
         virtual void shadeSpan(int x, int y, SkPMColor dstC[], int count) SK_OVERRIDE;
 
     private:
         SkMatrix    fDstToUnit;
         SkPMColor   fColors[3];
 
         typedef SkShader::Context INHERITED;
     };
 
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkTriColorShader)
 
 protected:
     SkTriColorShader(SkReadBuffer& buffer) : SkShader(buffer) {}
 
 private:
     typedef SkShader INHERITED;
 };
 
-SkShader::Context* SkTriColorShader::createContext(const SkBitmap& device, const SkPaint& paint,
-                                                   const SkMatrix& matrix, void* storage) const {
-    if (!this->validContext(device, paint, matrix)) {
+SkShader::Context* SkTriColorShader::createContext(const ContextRec& rec, void* storage) const {
+    if (!this->validContext(rec)) {
         return NULL;
     }
 
-    return SkNEW_PLACEMENT_ARGS(storage, TriColorShaderContext, (*this, device, paint, matrix));
+    return SkNEW_PLACEMENT_ARGS(storage, TriColorShaderContext, (*this, rec));
 }
 
 bool SkTriColorShader::TriColorShaderContext::setup(const SkPoint pts[], const SkColor colors[],
                                                     int index0, int index1, int index2) {
 
     fColors[0] = SkPreMultiplyColor(colors[index0]);
     fColors[1] = SkPreMultiplyColor(colors[index1]);
     fColors[2] = SkPreMultiplyColor(colors[index2]);
 
     SkMatrix m, im;
@@ skipping 19 matching lines @@
     if (scale < 0) {
         scale = 0;
     }
     if (scale > 255) {
         scale = 255;
     }
     return SkAlpha255To256(scale);
 }
 
 
-SkTriColorShader::TriColorShaderContext::TriColorShaderContext(
-        const SkTriColorShader& shader, const SkBitmap& device,
-        const SkPaint& paint, const SkMatrix& matrix)
-    : INHERITED(shader, device, paint, matrix) {}
+SkTriColorShader::TriColorShaderContext::TriColorShaderContext(const SkTriColorShader& shader,
+                                                               const ContextRec& rec)
+    : INHERITED(shader, rec) {}
 
 SkTriColorShader::TriColorShaderContext::~TriColorShaderContext() {}
 
 size_t SkTriColorShader::contextSize() const {
     return sizeof(TriColorShaderContext);
 }
 void SkTriColorShader::TriColorShaderContext::shadeSpan(int x, int y, SkPMColor dstC[], int count) {
     SkPoint src;
 
     for (int i = 0; i < count; i++) {
@@ skipping 386 matching lines @@
         mask->fImage = SkMask::AllocImage(size);
         memset(mask->fImage, 0, mask->computeImageSize());
     }
 
     if (SkMask::kJustComputeBounds_CreateMode != mode) {
         draw_into_mask(*mask, devPath, style);
     }
 
     return true;
 }