add ImageShader, sharing code with its Bitmap cousin

src/image/SkImage_Raster.cpp

 /*
  * Copyright 2012 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 "SkCanvas.h"
@@ skipping 56 matching lines @@
     const void* onPeekPixels(SkImageInfo*, size_t* /*rowBytes*/) const override;
     SkData* onRefEncoded() const override;
     bool getROPixels(SkBitmap*) const override;
 
     // exposed for SkSurface_Raster via SkNewImageFromPixelRef
     SkImage_Raster(const SkImageInfo&, SkPixelRef*, const SkIPoint& pixelRefOrigin, size_t rowBytes,
                    const SkSurfaceProps*);
 
     SkPixelRef* getPixelRef() const { return fBitmap.pixelRef(); }
 
-    SkShader* onNewShader(SkShader::TileMode,
-                          SkShader::TileMode,
-                          const SkMatrix* localMatrix) const override;
-
     bool isOpaque() const override;
     bool onAsLegacyBitmap(SkBitmap*, LegacyBitmapMode) const override;
 
     SkImage_Raster(const SkBitmap& bm, const SkSurfaceProps* props)
         : INHERITED(bm.width(), bm.height(), bm.getGenerationID(), props)
         , fBitmap(bm)
     {
         if (bm.pixelRef()->isPreLocked()) {
             // we only preemptively lock if there is no chance of triggering something expensive
             // like a lazy decode or imagegenerator. PreLocked means it is flat pixels already.
@@ skipping 40 matching lines @@
     : INHERITED(info.width(), info.height(), pr->getGenerationID(), props)
 {
     fBitmap.setInfo(info, rowBytes);
     fBitmap.setPixelRef(pr, pixelRefOrigin);
     fBitmap.lockPixels();
     SkASSERT(fBitmap.isImmutable());
 }
 
 SkImage_Raster::~SkImage_Raster() {}
 
-SkShader* SkImage_Raster::onNewShader(SkShader::TileMode tileX, SkShader::TileMode tileY,
-                                      const SkMatrix* localMatrix) const {
-    return SkShader::CreateBitmapShader(fBitmap, tileX, tileY, localMatrix);
-}
-
 SkSurface* SkImage_Raster::onNewSurface(const SkImageInfo& info, const SkSurfaceProps& props) const {
     return SkSurface::NewRaster(info, &props);
 }
 
 bool SkImage_Raster::onReadPixels(const SkImageInfo& dstInfo, void* dstPixels, size_t dstRowBytes,
                                   int srcX, int srcY) const {
     SkBitmap shallowCopy(fBitmap);
     return shallowCopy.readPixels(dstInfo, dstPixels, dstRowBytes, srcX, srcY);
 }
 
@@ skipping 117 matching lines @@
         // pixelref since the caller might call setImmutable() themselves
         // (thus changing our state).
         if (fBitmap.isImmutable()) {
             bitmap->setInfo(fBitmap.info(), fBitmap.rowBytes());
             bitmap->setPixelRef(fBitmap.pixelRef(), fBitmap.pixelRefOrigin());
             return true;
         }
     }
     return this->INHERITED::onAsLegacyBitmap(bitmap, mode);
 }