Add subsetting to SkScaledCodec

include/codec/SkScaledCodec.h

Index: include/codec/SkScaledCodec.h
diff --git a/include/codec/SkScaledCodec.h b/include/codec/SkScaledCodec.h
index 028706bc9400bfb7028ba75699029d2454277484..5d0d8834c4e3df3e378a19abf07328357d55b1ca 100644
--- a/include/codec/SkScaledCodec.h
+++ b/include/codec/SkScaledCodec.h
@@ -22,7 +22,7 @@ public:
 
     virtual ~SkScaledCodec();
 
-    static void ComputeSampleSize(const SkISize& dstDim, const SkISize& srcDim,
+    static void ComputeSampleSize(const SkISize& dstSize, const SkISize& srcSize,
                                   int* sampleSizeX, int* sampleSizeY);
 
 protected:
@@ -34,6 +34,8 @@ protected:
     SkISize onGetScaledDimensions(float desiredScale) const override;
     bool onDimensionsSupported(const SkISize&) override;
 
+    bool onGetScaledSubsetDimensions(float desiredScale, Options* options) const override;
+
     Result onGetPixels(const SkImageInfo&, void*, size_t, const Options&, SkPMColor*, int*, int*)
             override;
     SkEncodedFormat onGetEncodedFormat() const override {
@@ -50,6 +52,13 @@ protected:
 
 private:
 
+    Result nativeDecode(const SkImageInfo& scaledInfo, void* dst, size_t rowBytes,
+            const SkIRect& scaledSubsetRect, ZeroInitialized zeroInit, int* rowsDecoded);
+
+    Result sampledDecode(const SkImageInfo& decodeInfo, void* dst, size_t rowBytes,
+            const SkIRect& subsetRect, const SkIRect& scaledSubsetRect, int sampleX, int sampleY,
+            ZeroInitialized zeroInit, int* rowsDecoded);
+
     SkAutoTDelete<SkCodec> fCodec;
 
     explicit SkScaledCodec(SkCodec*);