Add subsetting to SkScaledCodec

src/codec/SkBmpCodec.h

Index: src/codec/SkBmpCodec.h
diff --git a/src/codec/SkBmpCodec.h b/src/codec/SkBmpCodec.h
index d76b0c41cf6a670c73056e59549a0dad2c217967..ecd45ae62fcbc0e16a6615ae7a2859c7992ef71b 100644
--- a/src/codec/SkBmpCodec.h
+++ b/src/codec/SkBmpCodec.h
@@ -90,6 +90,12 @@ protected:
      * Accessors used by subclasses
      */
     uint16_t bitsPerPixel() const { return fBitsPerPixel; }
+
+    int subsetLeft() const { return fSubsetLeft; }
+    int subsetWidth() const {return fSubsetWidth; }

[msarett, 2015/10/02 14:49:15]

I need to rename this.

This is different from the field in the base class because it is valid for
scanline decodes and regular decodes.

Ex: For regular decodes, it equals the full width instead of 0.

+
+private:
+
     SkScanlineOrder onGetScanlineOrder() const override { return fRowOrder; }
 
     /*
@@ -111,8 +117,6 @@ protected:
             const SkCodec::Options& options, SkPMColor inputColorPtr[],
             int* inputColorCount) = 0;
 
-private:
-
     /*
      * Creates a bmp decoder
      * Reads enough of the stream to determine the image format
@@ -138,13 +142,16 @@ private:
             const Options& opts) = 0;
 
     Result onStartScanlineDecode(const SkImageInfo& dstInfo, const SkCodec::Options&,
-            SkPMColor inputColorPtr[], int* inputColorCount) override;
+            SkPMColor inputColorPtr[], int* inputColorCount, int subsetLeft, int subsetWidth)
+            override;
 
     int onGetScanlines(void* dst, int count, size_t rowBytes) override;
 
     // TODO(msarett): Override default skipping with something more clever.
 
     const uint16_t          fBitsPerPixel;
+    int                     fSubsetLeft;
+    int                     fSubsetWidth;
     const SkScanlineOrder   fRowOrder;
 
     typedef SkCodec INHERITED;