add ImageShader, sharing code with its Bitmap cousin

src/image/SkImage_Generator.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkImage_Base.h"
 #include "SkBitmap.h"
 #include "SkData.h"
@@ skipping 10 matching lines @@
     {}
 
     SkSurface* onNewSurface(const SkImageInfo&, const SkSurfaceProps&) const override;
     bool onReadPixels(const SkImageInfo&, void*, size_t, int srcX, int srcY) const override;
     const void* onPeekPixels(SkImageInfo*, size_t* /*rowBytes*/) const override;
     SkData* onRefEncoded() const override;
     bool isOpaque() const override { return fCache->info().isOpaque(); }
 
     bool getROPixels(SkBitmap*) const override;
     GrTexture* asTextureRef(GrContext*, SkImageUsageType) const override;
-
-    SkShader* onNewShader(SkShader::TileMode,
-                          SkShader::TileMode,
-                          const SkMatrix* localMatrix) const override;
-
     bool onIsLazyGenerated() const override { return true; }
 
 private:
     SkAutoTDelete<SkImageCacherator> fCache;
 
     typedef SkImage_Base INHERITED;
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 
-SkShader* SkImage_Generator::onNewShader(SkShader::TileMode tileX, SkShader::TileMode tileY,
-                                         const SkMatrix* localMatrix) const {
-    // TODO: need a native Shader that takes Cacherator (or this image) so we can natively return
-    // textures as output from the shader.
-    SkBitmap bm;
-    if (this->getROPixels(&bm)) {
-        return SkShader::CreateBitmapShader(bm, tileX, tileY, localMatrix);
-    }
-    return nullptr;
-}
-
 SkSurface* SkImage_Generator::onNewSurface(const SkImageInfo& info,
                                            const SkSurfaceProps& props) const {
     return SkSurface::NewRaster(info, &props);
 }
 
 bool SkImage_Generator::onReadPixels(const SkImageInfo& dstInfo, void* dstPixels, size_t dstRB,
                                      int srcX, int srcY) const {
     SkBitmap bm;
     if (this->getROPixels(&bm)) {
         return bm.readPixels(dstInfo, dstPixels, dstRB, srcX, srcY);
@@ skipping 17 matching lines @@
     return fCache->lockAsTexture(ctx, usage, this);
 }
 
 SkImage* SkImage::NewFromGenerator(SkImageGenerator* generator, const SkIRect* subset) {
     SkImageCacherator* cache = SkImageCacherator::NewFromGenerator(generator, subset);
     if (!cache) {
         return nullptr;
     }
     return SkNEW_ARGS(SkImage_Generator, (cache));
 }