Make SkAndroidCodec support gif

src/codec/SkSwizzler.h

Index: src/codec/SkSwizzler.h
diff --git a/src/codec/SkSwizzler.h b/src/codec/SkSwizzler.h
index 691dc77aa6a99f20cc676f7b3f854b8655a060f1..f17b97bd62790c5f3ec484ae50064b9cbd7a3075 100644
--- a/src/codec/SkSwizzler.h
+++ b/src/codec/SkSwizzler.h
@@ -127,10 +127,15 @@ public:
      *                         implementation may choose to skip writing zeroes
      *                         if set to kYes_ZeroInitialized.
      *                 Contains subset information.
+     *  @param frame   Indicates if the source pixels represent an image frame
+     *                 that is a subset of the full image.  This is subtlely
+     *                 different than if the client requests a subset decode,

[scroggo, 2015/11/17 14:56:26]

Maybe explain how it's different? Or where an explanation can be found?

[msarett, 2015/11/17 18:00:50]

Done.

+     *                 and must be handled differently.
      *  @return A new SkSwizzler or nullptr on failure.
      */
     static SkSwizzler* CreateSwizzler(SrcConfig, const SkPMColor* ctable,
-                                      const SkImageInfo& dstInfo, const SkCodec::Options&);
+                                      const SkImageInfo& dstInfo, const SkCodec::Options&,
+                                      const SkIRect* frame = nullptr);
 
     /**
      *  Swizzle a line. Generally this will be called height times, once
@@ -151,7 +156,7 @@ public:
      */
     void fill(const SkImageInfo& info, void* dst, size_t rowBytes, uint32_t colorOrIndex,
             SkCodec::ZeroInitialized zeroInit) override {
-        const SkImageInfo fillInfo = info.makeWH(fDstWidth, info.height());
+        const SkImageInfo fillInfo = info.makeWH(fAllocatedWidth, info.height());
         SkSampler::Fill(fillInfo, dst, rowBytes, colorOrIndex, zeroInit);
     }
 
@@ -178,17 +183,28 @@ private:
     const SkPMColor*    fColorTable;      // Unowned pointer
     const int           fSrcOffset;       // Offset of the src in pixels, allows for partial
                                           // scanline decodes.
-    int                 fX0;              // Start coordinate for the src, may be different than
-                                          // fSrcOffset if we are sampling.
-    const int           fSubsetWidth;     // Width of the subset of the source before any sampling.
-    int                 fDstWidth;        // Width of dst, which may differ with sampling.
+    const int           fDstOffset;       // Offset of the dst in pixels, allows the src to be

[scroggo, 2015/11/17 14:56:26]

a* partial frame... ?

[msarett, 2015/11/17 18:00:50]

Acknowledged.

+                                          // partial frame of the dst.
+    int                 fSrcOffsetBytes;  // Byte offset of the src, takes sampling into account.
+    int                 fDstOffsetBytes;  // Byte offset of the dst, takes sampling into account.
+    const int           fSrcWidth;        // Pixel width of src before any sampling, accounting
+                                          // for subset decodes.

[scroggo, 2015/11/17 14:56:26]

When you say "accounting for subset decodes", what do you mean? Partial
scanlines? So this is the width of the source subset? Or GIF subset frames? So
this is the width of the frame?

[msarett, 2015/11/17 18:00:50]

Acknowledged.

+    const int           fDstWidth;        // Pixel width of dst before any sampling, accounting
+                                          // subset decodes or image frame subsets.
+    int                 fSwizzleWidth;    // The number of pixels that will be written by the
+                                          // RowProc.  Scaled version of fSrcWidth.
+    int                 fAllocatedWidth;  // The pixel width of destination memory.  Scaled version
+                                          // of fDstWidth.
     int                 fSampleX;         // step between X samples
-    const int           fBPP;             // if bitsPerPixel % 8 == 0
+    const int           fSrcBPP;          // Bits/bytes per pixel for the SrcConfig
+                                          // if bitsPerPixel % 8 == 0
                                           //     fBPP is bytesPerPixel
                                           // else
                                           //     fBPP is bitsPerPixel
+    const int           fDstBPP;          // Bytes per pixel for the destination color type
 
-    SkSwizzler(RowProc proc, const SkPMColor* ctable, int srcOffset, int subsetWidth, int bpp);
+    SkSwizzler(RowProc proc, const SkPMColor* ctable, int srcOffset, int srcWidth, int dstOffset,
+            int dstWidth, int srcBPP, int dstBPP);
 
     int onSetSampleX(int) override;