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

BUG=skia:
R=scroggo@google.com, dominikg@chromium.org

Author: reed@google.com

Review URL: https://codereview.chromium.org/264843006

git-svn-id: http://skia.googlecode.com/svn/trunk/include@14514 2bbb7eff-a529-9590-31e7-b0007b416f81

6 files changed, 31 insertions, 33 deletions

diff --git a/core/SkColorShader.h b/core/SkColorShader.h
index 9e19a71..f993959 100644
--- a/core/SkColorShader.h
+++ b/core/SkColorShader.h
@@ -27,10 +27,7 @@ public:
 
     virtual bool isOpaque() const SK_OVERRIDE;
 
-    virtual SkShader::Context* createContext(const SkBitmap& device,
-                                             const SkPaint& paint,
-                                             const SkMatrix& matrix,
-                                             void* storage) const SK_OVERRIDE;
+    virtual SkShader::Context* createContext(const ContextRec&, void* storage) const SK_OVERRIDE;
 
     virtual size_t contextSize() const SK_OVERRIDE {
         return sizeof(ColorShaderContext);
@@ -38,8 +35,7 @@ public:
 
     class ColorShaderContext : public SkShader::Context {
     public:
-        ColorShaderContext(const SkColorShader& shader, const SkBitmap& device,
-                           const SkPaint& paint, const SkMatrix& matrix);
+        ColorShaderContext(const SkColorShader& shader, const ContextRec&);
 
         virtual uint32_t getFlags() const SK_OVERRIDE;
         virtual uint8_t getSpan16Alpha() const SK_OVERRIDE;
diff --git a/core/SkComposeShader.h b/core/SkComposeShader.h
index d42da0c..ac3c32b 100644
--- a/core/SkComposeShader.h
+++ b/core/SkComposeShader.h
@@ -34,18 +34,15 @@ public:
     SkComposeShader(SkShader* sA, SkShader* sB, SkXfermode* mode = NULL);
     virtual ~SkComposeShader();
 
-    virtual bool validContext(const SkBitmap&, const SkPaint&,
-                              const SkMatrix&, SkMatrix* totalInverse = NULL) const SK_OVERRIDE;
-    virtual SkShader::Context* createContext(const SkBitmap&, const SkPaint&,
-                                             const SkMatrix&, void*) const SK_OVERRIDE;
+    virtual bool validContext(const ContextRec&, SkMatrix* totalInverse = NULL) const SK_OVERRIDE;
+    virtual SkShader::Context* createContext(const ContextRec&, void*) const SK_OVERRIDE;
     virtual size_t contextSize() const SK_OVERRIDE;
 
     class ComposeShaderContext : public SkShader::Context {
     public:
         // When this object gets destroyed, it will call contextA and contextB's destructor
         // but it will NOT free the memory.
-        ComposeShaderContext(const SkComposeShader&, const SkBitmap&,
-                             const SkPaint&, const SkMatrix&,
+        ComposeShaderContext(const SkComposeShader&, const ContextRec&,
                              SkShader::Context* contextA, SkShader::Context* contextB);
 
         SkShader::Context* getShaderContextA() const { return fShaderContextA; }
diff --git a/core/SkEmptyShader.h b/core/SkEmptyShader.h
index 7494eff..d1a067f 100644
--- a/core/SkEmptyShader.h
+++ b/core/SkEmptyShader.h
@@ -27,13 +27,11 @@ public:
         return sizeof(SkShader::Context);
     }
 
-    virtual bool validContext(const SkBitmap&, const SkPaint&,
-                              const SkMatrix&, SkMatrix* totalInverse = NULL) const SK_OVERRIDE {
+    virtual bool validContext(const ContextRec&, SkMatrix* totalInverse = NULL) const SK_OVERRIDE {
         return false;
     }
 
-    virtual SkShader::Context* createContext(const SkBitmap&, const SkPaint&,
-                                             const SkMatrix&, void*) const SK_OVERRIDE {
+    virtual SkShader::Context* createContext(const ContextRec&, void*) const SK_OVERRIDE {
         // validContext returns false.
         return NULL;
     }
diff --git a/core/SkShader.h b/core/SkShader.h
index b0a7fd9..32707d7 100644
--- a/core/SkShader.h
+++ b/core/SkShader.h
@@ -119,10 +119,26 @@ public:
      */
     virtual bool isOpaque() const { return false; }
 
+    /**
+     *  ContextRec acts as a parameter bundle for creating Contexts.
+     */
+    struct ContextRec {
+        ContextRec() : fDevice(NULL), fPaint(NULL), fMatrix(NULL) {}
+        ContextRec(const ContextRec& other)
+            : fDevice(other.fDevice), fPaint(other.fPaint), fMatrix(other.fMatrix) {}
+        ContextRec(const SkBitmap& device, const SkPaint& paint, const SkMatrix& matrix)
+            : fDevice(&device)
+            , fPaint(&paint)
+            , fMatrix(&matrix) {}
+
+        const SkBitmap* fDevice;    // the bitmap we are drawing into
+        const SkPaint*  fPaint;     // the current paint associated with the draw
+        const SkMatrix* fMatrix;    // the current matrix in the canvas
+    };
+
     class Context : public ::SkNoncopyable {
     public:
-        Context(const SkShader& shader, const SkBitmap& device,
-                const SkPaint& paint, const SkMatrix& matrix);
+        Context(const SkShader& shader, const ContextRec&);
 
         virtual ~Context();
 
@@ -200,8 +216,7 @@ public:
      *  Subclasses should be sure to call their INHERITED::validContext() if
      *  they override this method.
      */
-    virtual bool validContext(const SkBitmap& device, const SkPaint& paint,
-                              const SkMatrix& matrix, SkMatrix* totalInverse = NULL) const;
+    virtual bool validContext(const ContextRec&, SkMatrix* totalInverse = NULL) const;
 
     /**
      *  Create the actual object that does the shading.
@@ -211,10 +226,7 @@ public:
      *
      *  Base class implementation returns NULL.
      */
-    virtual Context* createContext(const SkBitmap& device,
-                                   const SkPaint& paint,
-                                   const SkMatrix& matrix,
-                                   void* storage) const;
+    virtual Context* createContext(const ContextRec&, void* storage) const;
 
     /**
      *  Return the size of a Context returned by createContext.
diff --git a/effects/SkPerlinNoiseShader.h b/effects/SkPerlinNoiseShader.h
index 5b27029..2766df0 100644
--- a/effects/SkPerlinNoiseShader.h
+++ b/effects/SkPerlinNoiseShader.h
@@ -72,15 +72,12 @@ public:
     }
 
 
-    virtual SkShader::Context* createContext(
-        const SkBitmap& device, const SkPaint& paint,
-        const SkMatrix& matrix, void* storage) const SK_OVERRIDE;
+    virtual SkShader::Context* createContext(const ContextRec&, void* storage) const SK_OVERRIDE;
     virtual size_t contextSize() const SK_OVERRIDE;
 
     class PerlinNoiseShaderContext : public SkShader::Context {
     public:
-        PerlinNoiseShaderContext(const SkPerlinNoiseShader& shader, const SkBitmap& device,
-                                 const SkPaint& paint, const SkMatrix& matrix);
+        PerlinNoiseShaderContext(const SkPerlinNoiseShader& shader, const ContextRec&);
         virtual ~PerlinNoiseShaderContext() {}
 
         virtual void shadeSpan(int x, int y, SkPMColor[], int count) SK_OVERRIDE;
diff --git a/effects/SkTransparentShader.h b/effects/SkTransparentShader.h
index 790e5ae..55513eb 100644
--- a/effects/SkTransparentShader.h
+++ b/effects/SkTransparentShader.h
@@ -14,15 +14,13 @@ class SK_API SkTransparentShader : public SkShader {
 public:
     SkTransparentShader() {}
 
-    virtual SkShader::Context* createContext(const SkBitmap& device, const SkPaint& paint,
-                                             const SkMatrix& matrix, void* storage) const
+    virtual SkShader::Context* createContext(const ContextRec&, void* storage) const
             SK_OVERRIDE;
     virtual size_t contextSize() const SK_OVERRIDE;
 
     class TransparentShaderContext : public SkShader::Context {
     public:
-        TransparentShaderContext(const SkTransparentShader& shader, const SkBitmap& device,
-                                 const SkPaint& paint, const SkMatrix& matrix);
+        TransparentShaderContext(const SkTransparentShader& shader, const ContextRec&);
         virtual ~TransparentShaderContext();
 
         virtual uint32_t getFlags() const SK_OVERRIDE;