Add SkShader::asShadeProc to fast-path the caller when the shader is fast

Review URL: https://codereview.appspot.com/6649055

git-svn-id: http://skia.googlecode.com/svn/trunk@5930 2bbb7eff-a529-9590-31e7-b0007b416f81

include/core/SkShader.h

@@ -148,6 +148,9 @@ public:
      */
     virtual void shadeSpan(int x, int y, SkPMColor[], int count) = 0;
 
+    typedef void (*ShadeProc)(void* ctx, int x, int y, SkPMColor[], int count);
+    virtual ShadeProc asAShadeProc(void** ctx);
+
     /**
      *  Called only for 16bit devices when getFlags() returns
      *  kOpaqueAlphaFlag | kHasSpan16_Flag

src/core/SkBitmapProcShader.cpp

@@ -203,6 +203,14 @@ void SkBitmapProcShader::shadeSpan(int x, int y, SkPMColor dstC[], int count) {
     }
 }
 
+SkShader::ShadeProc SkBitmapProcShader::asAShadeProc(void** ctx) {
+    if (fState.getShaderProc32()) {
+        *ctx = &fState;
+        return (ShadeProc)fState.getShaderProc32();
+    }
+    return NULL;
+}
+
 void SkBitmapProcShader::shadeSpan16(int x, int y, uint16_t dstC[], int count) {
     const SkBitmapProcState& state = fState;
     if (state.getShaderProc16()) {

src/core/SkBitmapProcShader.h

@@ -22,6 +22,7 @@ public:
     virtual bool setContext(const SkBitmap&, const SkPaint&, const SkMatrix&);
     virtual uint32_t getFlags() { return fFlags; }
     virtual void shadeSpan(int x, int y, SkPMColor dstC[], int count);
+    virtual ShadeProc asAShadeProc(void** ctx) SK_OVERRIDE;
     virtual void shadeSpan16(int x, int y, uint16_t dstC[], int count);
     virtual void beginSession();
     virtual void endSession();

src/core/SkBlitter_ARGB32.cpp

@@ -303,6 +303,52 @@ void SkARGB32_Shader_Blitter::blitH(int x, int y, int width) {
     }
 }
 
+void SkARGB32_Shader_Blitter::blitRect(int x, int y, int width, int height) {
+    SkASSERT(x >= 0 && y >= 0 &&
+             x + width <= fDevice.width() && y + height <= fDevice.height());
+    
+    uint32_t*   device = fDevice.getAddr32(x, y);
+    size_t      deviceRB = fDevice.rowBytes();
+    SkShader*   shader = fShader;
+
+    if (fXfermode == NULL && (shader->getFlags() & SkShader::kOpaqueAlpha_Flag)) {
+        void* ctx;
+        SkShader::ShadeProc shadeProc = fShader->asAShadeProc(&ctx);
+        if (shadeProc) {
+            do {
+                shadeProc(ctx, x, y, device, width);
+                y += 1;
+                device = (uint32_t*)((char*)device + deviceRB);
+            } while (--height > 0);
+        } else {
+            do {
+                shader->shadeSpan(x, y, device, width);
+                y += 1;
+                device = (uint32_t*)((char*)device + deviceRB);
+            } while (--height > 0);
+        }
+    } else {
+        SkPMColor* span = fBuffer;
+        SkXfermode* xfer = fXfermode;
+        if (xfer) {
+            do {
+                shader->shadeSpan(x, y, span, width);
+                xfer->xfer32(device, span, width, NULL);
+                y += 1;
+                device = (uint32_t*)((char*)device + deviceRB);
+            } while (--height > 0);
+        } else {
+            SkBlitRow::Proc32 proc = fProc32;
+            do {
+                shader->shadeSpan(x, y, span, width);
+                proc(device, span, width, 255);
+                y += 1;
+                device = (uint32_t*)((char*)device + deviceRB);
+            } while (--height > 0);
+        }
+    }
+}
+
 void SkARGB32_Shader_Blitter::blitAntiH(int x, int y, const SkAlpha antialias[],
                                         const int16_t runs[]) {
     SkPMColor*  span = fBuffer;

src/core/SkCoreBlitters.h

@@ -130,18 +130,19 @@ public:
     SkARGB32_Shader_Blitter(const SkBitmap& device, const SkPaint& paint);
     virtual ~SkARGB32_Shader_Blitter();
     virtual void blitH(int x, int y, int width);
+    virtual void blitRect(int x, int y, int width, int height) SK_OVERRIDE;
     virtual void blitAntiH(int x, int y, const SkAlpha antialias[], const int16_t runs[]);
     virtual void blitMask(const SkMask&, const SkIRect&);
-
+    
 private:
     SkXfermode*         fXfermode;
     SkPMColor*          fBuffer;
     SkBlitRow::Proc32   fProc32;
     SkBlitRow::Proc32   fProc32Blend;
-
+    
     // illegal
     SkARGB32_Shader_Blitter& operator=(const SkARGB32_Shader_Blitter&);
-
+    
     typedef SkShaderBlitter INHERITED;
 };
 

src/core/SkShader.cpp

@@ -103,6 +103,10 @@ bool SkShader::setContext(const SkBitmap& device,
     return false;
 }
 
+SkShader::ShadeProc SkShader::asAShadeProc(void** ctx) {
+    return NULL;
+}
+
 #include "SkColorPriv.h"
 
 void SkShader::shadeSpan16(int x, int y, uint16_t span16[], int count) {