remove unused (by the outside) SkImage::newSurface, and simplify newImage -> newSubset

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 49 matching lines @@
 
         if (minSize) {
             *minSize = size;
         }
         return true;
     }
 
     SkImage_Raster(const SkImageInfo&, SkData*, size_t rb, SkColorTable*, const SkSurfaceProps*);
     virtual ~SkImage_Raster();
 
-    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 getROPixels(SkBitmap*) const override;
     GrTexture* asTextureRef(GrContext*, SkImageUsageType) const override;
+    SkImage* onNewSubset(const SkIRect&) 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;
@@ skipping 56 matching lines @@
     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);
 }
 
 const void* SkImage_Raster::onPeekPixels(SkImageInfo* infoPtr, size_t* rowBytesPtr) const {
     const SkImageInfo info = fBitmap.info();
     if ((kUnknown_SkColorType == info.colorType()) || !fBitmap.getPixels()) {
         return nullptr;
@@ skipping 39 matching lines @@
 
     if (GrTexture* tex = ctx->textureProvider()->findAndRefTextureByUniqueKey(key)) {
         return tex;
     }
     return GrRefCachedBitmapTexture(ctx, fBitmap, usage);
 #endif
     
     return nullptr;
 }
 
+SkImage* SkImage_Raster::onNewSubset(const SkIRect& subset) const {
+    // TODO : could consider heurist of sharing pixels, if subset is pretty close to complete
+
+    SkImageInfo info = SkImageInfo::MakeN32(subset.width(), subset.height(), fBitmap.alphaType());
+    SkAutoTUnref<SkSurface> surface(SkSurface::NewRaster(info));
+    if (!surface) {
+        return nullptr;
+    }
+    surface->getCanvas()->clear(0);
+    surface->getCanvas()->drawImage(this, SkIntToScalar(-subset.x()), SkIntToScalar(-subset.y()),
+                                    nullptr);
+    return surface->newImageSnapshot();
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 SkImage* SkImage::NewRasterCopy(const SkImageInfo& info, const void* pixels, size_t rowBytes,
                                 SkColorTable* ctable) {
     size_t size;
     if (!SkImage_Raster::ValidArgs(info, rowBytes, ctable, &size) || !pixels) {
         return nullptr;
     }
 
     // Here we actually make a copy of the caller's pixel data
@@ skipping 80 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);
 }