add ImageShader, sharing code with its Bitmap cousin

src/core/SkBitmapProcShader.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmapProcShader.h"
 #include "SkBitmapProcState.h"
 #include "SkColorPriv.h"
 #include "SkErrorInternals.h"
 #include "SkPixelRef.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
 
 #if SK_SUPPORT_GPU
 #include "effects/GrBicubicEffect.h"
 #include "effects/GrExtractAlphaFragmentProcessor.h"
 #include "effects/GrSimpleTextureEffect.h"
 #endif
 
+size_t SkBitmapProcShader::ContextSize() {
+    // The SkBitmapProcState is stored outside of the context object, with the context holding
+    // a pointer to it.
+    return sizeof(BitmapProcShaderContext) + sizeof(SkBitmapProcState);
+}
+
 SkBitmapProcShader::SkBitmapProcShader(const SkBitmap& src, TileMode tmx, TileMode tmy,
                                        const SkMatrix* localMatrix)
         : INHERITED(localMatrix) {
     fRawBitmap = src;
     fTileModeX = (uint8_t)tmx;
     fTileModeY = (uint8_t)tmy;
 }
 
 bool SkBitmapProcShader::onIsABitmap(SkBitmap* texture, SkMatrix* texM, TileMode xy[]) const {
     if (texture) {
@@ skipping 31 matching lines @@
 
 static bool only_scale_and_translate(const SkMatrix& matrix) {
     unsigned mask = SkMatrix::kTranslate_Mask | SkMatrix::kScale_Mask;
     return (matrix.getType() & ~mask) == 0;
 }
 
 bool SkBitmapProcShader::isOpaque() const {
     return fRawBitmap.isOpaque();
 }
 
-SkShader::Context* SkBitmapProcShader::onCreateContext(const ContextRec& rec, void* storage) const {
+SkShader::Context* SkBitmapProcShader::MakeContext(const SkShader& shader,
+                                                   TileMode tmx, TileMode tmy,
+                                                   const SkBitmap& bitmap,
+                                                   const ContextRec& rec, void* storage) {
     SkMatrix totalInverse;
     // Do this first, so we know the matrix can be inverted.
-    if (!this->computeTotalInverse(rec, &totalInverse)) {
+    if (!shader.computeTotalInverse(rec, &totalInverse)) {
         return nullptr;
     }
 
     void* stateStorage = (char*)storage + sizeof(BitmapProcShaderContext);
     SkBitmapProcState* state = new (stateStorage) SkBitmapProcState;
 
     SkASSERT(state);
-    state->fTileModeX = fTileModeX;
-    state->fTileModeY = fTileModeY;
-    state->fOrigBitmap = fRawBitmap;
+    state->fTileModeX = tmx;
+    state->fTileModeY = tmy;
+    state->fOrigBitmap = bitmap;
     if (!state->chooseProcs(totalInverse, *rec.fPaint)) {
         state->~SkBitmapProcState();
         return nullptr;
     }
 
-    return new (storage) BitmapProcShaderContext(*this, rec, state);
+    return new (storage) BitmapProcShaderContext(shader, rec, state);
 }
 
-size_t SkBitmapProcShader::contextSize() const {
-    // The SkBitmapProcState is stored outside of the context object, with the context holding
-    // a pointer to it.
-    return sizeof(BitmapProcShaderContext) + sizeof(SkBitmapProcState);
+SkShader::Context* SkBitmapProcShader::onCreateContext(const ContextRec& rec, void* storage) const {
+    return MakeContext(*this, (TileMode)fTileModeX, (TileMode)fTileModeY, fRawBitmap, rec, storage);
 }
 
-SkBitmapProcShader::BitmapProcShaderContext::BitmapProcShaderContext(
-        const SkBitmapProcShader& shader, const ContextRec& rec, SkBitmapProcState* state)
+SkBitmapProcShader::BitmapProcShaderContext::BitmapProcShaderContext(const SkShader& shader,
+                                                                     const ContextRec& rec,
+                                                                     SkBitmapProcState* state)
     : INHERITED(shader, rec)
     , fState(state)
 {
     const SkPixmap& pixmap = fState->fPixmap;
     bool isOpaque = pixmap.isOpaque();
 
     // update fFlags
     uint32_t flags = 0;
     if (isOpaque && (255 == this->getPaintAlpha())) {
         flags |= kOpaqueAlpha_Flag;
@@ skipping 288 matching lines @@
         inner.reset(GrSimpleTextureEffect::Create(procDataManager, texture, matrix, params));
     }
 
     if (kAlpha_8_SkColorType == fRawBitmap.colorType()) {
         return SkRef(inner.get());
     }
     return GrExtractAlphaFragmentProcessor::Create(inner);
 }
 
 #endif