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

src/core/SkComposeShader.cpp

Index: src/core/SkComposeShader.cpp
diff --git a/src/core/SkComposeShader.cpp b/src/core/SkComposeShader.cpp
index 77bc46f30a3fc98798478a0ed621861e9955c765..f53eedf8764d01e275be11801243a6d0189258a1 100644
--- a/src/core/SkComposeShader.cpp
+++ b/src/core/SkComposeShader.cpp
@@ -45,10 +45,6 @@
     fShaderA->unref();
 }
 
-size_t SkComposeShader::contextSize() const {
-    return sizeof(ComposeShaderContext) + fShaderA->contextSize() + fShaderB->contextSize();
-}
-
 class SkAutoAlphaRestore {
 public:
     SkAutoAlphaRestore(SkPaint* paint, uint8_t newAlpha) {
@@ -73,34 +69,18 @@
     buffer.writeFlattenable(fMode);
 }
 
-/*  We call validContext/createContext on our two worker shaders.
-    However, we always let them see opaque alpha, and if the paint
-    really is translucent, then we apply that after the fact.
+/*  We call setContext on our two worker shaders. However, we
+    always let them see opaque alpha, and if the paint really
+    is translucent, then we apply that after the fact.
 
+    We need to keep the calls to setContext/endContext balanced, since if we
+    return false, our endContext() will not be called.
  */
-bool SkComposeShader::validContext(const SkBitmap& device,
-                                   const SkPaint& paint,
-                                   const SkMatrix& matrix,
-                                   SkMatrix* totalInverse) const {
-    if (!this->INHERITED::validContext(device, paint, matrix, totalInverse)) {
+bool SkComposeShader::setContext(const SkBitmap& device,
+                                 const SkPaint& paint,
+                                 const SkMatrix& matrix) {
+    if (!this->INHERITED::setContext(device, paint, matrix)) {
         return false;
-    }
-
-    // we preconcat our localMatrix (if any) with the device matrix
-    // before calling our sub-shaders
-
-    SkMatrix tmpM;
-
-    tmpM.setConcat(matrix, this->getLocalMatrix());
-
-    return fShaderA->validContext(device, paint, tmpM) &&
-           fShaderB->validContext(device, paint, tmpM);
-}
-
-SkShader::Context* SkComposeShader::createContext(const SkBitmap& device, const SkPaint& paint,
-                                                  const SkMatrix& matrix, void* storage) const {
-    if (!this->validContext(device, paint, matrix)) {
-        return NULL;
     }
 
     // we preconcat our localMatrix (if any) with the device matrix
@@ -112,43 +92,36 @@
 
     SkAutoAlphaRestore  restore(const_cast<SkPaint*>(&paint), 0xFF);
 
-    char* aStorage = (char*) storage + sizeof(ComposeShaderContext);
-    char* bStorage = aStorage + fShaderA->contextSize();
-
-    SkShader::Context* contextA = fShaderA->createContext(device, paint, tmpM, aStorage);
-    SkShader::Context* contextB = fShaderB->createContext(device, paint, tmpM, bStorage);
-
-    // Both functions must succeed; otherwise validContext should have returned
-    // false.
-    SkASSERT(contextA);
-    SkASSERT(contextB);
-
-    return SkNEW_PLACEMENT_ARGS(storage, ComposeShaderContext,
-                                (*this, device, paint, matrix, contextA, contextB));
+    bool setContextA = fShaderA->setContext(device, paint, tmpM);
+    bool setContextB = fShaderB->setContext(device, paint, tmpM);
+    if (!setContextA || !setContextB) {
+        if (setContextB) {
+            fShaderB->endContext();
+        }
+        else if (setContextA) {
+            fShaderA->endContext();
+        }
+        this->INHERITED::endContext();
+        return false;
+    }
+    return true;
 }
 
-SkComposeShader::ComposeShaderContext::ComposeShaderContext(
-        const SkComposeShader& shader, const SkBitmap& device,
-        const SkPaint& paint, const SkMatrix& matrix,
-        SkShader::Context* contextA, SkShader::Context* contextB)
-    : INHERITED(shader, device, paint, matrix)
-    , fShaderContextA(contextA)
-    , fShaderContextB(contextB) {}
-
-SkComposeShader::ComposeShaderContext::~ComposeShaderContext() {
-    fShaderContextA->~Context();
-    fShaderContextB->~Context();
+void SkComposeShader::endContext() {
+    fShaderB->endContext();
+    fShaderA->endContext();
+    this->INHERITED::endContext();
 }
 
 // larger is better (fewer times we have to loop), but we shouldn't
 // take up too much stack-space (each element is 4 bytes)
 #define TMP_COLOR_COUNT     64
 
-void SkComposeShader::ComposeShaderContext::shadeSpan(int x, int y, SkPMColor result[], int count) {
-    SkShader::Context* shaderContextA = fShaderContextA;
-    SkShader::Context* shaderContextB = fShaderContextB;
-    SkXfermode*        mode = static_cast<const SkComposeShader&>(fShader).fMode;
-    unsigned           scale = SkAlpha255To256(this->getPaintAlpha());
+void SkComposeShader::shadeSpan(int x, int y, SkPMColor result[], int count) {
+    SkShader*   shaderA = fShaderA;
+    SkShader*   shaderB = fShaderB;
+    SkXfermode* mode = fMode;
+    unsigned    scale = SkAlpha255To256(this->getPaintAlpha());
 
     SkPMColor   tmp[TMP_COLOR_COUNT];
 
@@ -161,8 +134,8 @@
                 n = TMP_COLOR_COUNT;
             }
 
-            shaderContextA->shadeSpan(x, y, result, n);
-            shaderContextB->shadeSpan(x, y, tmp, n);
+            shaderA->shadeSpan(x, y, result, n);
+            shaderB->shadeSpan(x, y, tmp, n);
 
             if (256 == scale) {
                 for (int i = 0; i < n; i++) {
@@ -186,8 +159,8 @@
                 n = TMP_COLOR_COUNT;
             }
 
-            shaderContextA->shadeSpan(x, y, result, n);
-            shaderContextB->shadeSpan(x, y, tmp, n);
+            shaderA->shadeSpan(x, y, result, n);
+            shaderB->shadeSpan(x, y, tmp, n);
             mode->xfer32(result, tmp, n, NULL);
 
             if (256 == scale) {