Scanline decoding for gifs
BUG=skia:
Committed: https://skia.googlesource.com/skia/+/e9c10b9121887e8c300bd41357461418e061984d
Review URL: https://codereview.chromium.org/1305123002
diff --git a/src/codec/SkCodec_libgif.h b/src/codec/SkCodec_libgif.h
index df01088..8845536 100644
--- a/src/codec/SkCodec_libgif.h
+++ b/src/codec/SkCodec_libgif.h
@@ -6,7 +6,10 @@
*/
#include "SkCodec.h"
+#include "SkColorTable.h"
#include "SkImageInfo.h"
+#include "SkScanlineDecoder.h"
+#include "SkSwizzler.h"
#include "gif_lib.h"
@@ -29,7 +32,8 @@
* Reads enough of the stream to determine the image format
*/
static SkCodec* NewFromStream(SkStream*);
-
+
+ static SkScanlineDecoder* NewSDFromStream(SkStream* stream);
protected:
@@ -52,10 +56,11 @@
* Ownership is unchanged when we returned a gifOut.
*
*/
- static bool ReadHeader(SkStream* stream, SkCodec** codecOut, GifFileType** gifOut);
+ static bool ReadHeader(SkStream* stream, SkCodec** codecOut,
+ GifFileType** gifOut);
/*
- * Initiates the gif decode
+ * Performs the full gif decode
*/
Result onGetPixels(const SkImageInfo&, void*, size_t, const Options&,
SkPMColor*, int32_t*) override;
@@ -69,6 +74,67 @@
private:
/*
+ * A gif can contain multiple image frames. We will only decode the first
+ * frame. This function reads up to the first image frame, processing
+ * transparency and/or animation information that comes before the image
+ * data.
+ *
+ * @param gif Pointer to the library type that manages the gif decode
+ * @param transIndex This call will set the transparent index based on the
+ * extension data.
+ */
+ static SkCodec::Result ReadUpToFirstImage(GifFileType* gif, uint32_t* transIndex);
+
+ /*
+ * A gif may contain many image frames, all of different sizes.
+ * This function checks if the frame dimensions are valid and corrects
+ * them if necessary. It then sets fFrameDims to the corrected
+ * dimensions.
+ *
+ * @param desc The image frame descriptor
+ */
+ bool setFrameDimensions(const GifImageDesc& desc);
+
+ /*
+ * Initializes the color table that we will use for decoding.
+ *
+ * @param dstInfo Contains the requested dst color type.
+ * @param inputColorPtr Copies the encoded color table to the client's
+ * input color table if the client requests kIndex8.
+ * @param inputColorCount If the client requests kIndex8, sets
+ * inputColorCount to 256. Since gifs always
+ * contain 8-bit indices, we need a 256 entry color
+ * table to ensure that indexing is always in
+ * bounds.
+ */
+ void initializeColorTable(const SkImageInfo& dstInfo, SkPMColor* colorPtr,
+ int* inputColorCount);
+
+ /*
+ * Checks for invalid inputs and calls rewindIfNeeded(), setFramDimensions(), and
+ * initializeColorTable() in the proper sequence.
+ */
+ SkCodec::Result prepareToDecode(const SkImageInfo& dstInfo, SkPMColor* inputColorPtr,
+ int* inputColorCount, const Options& opts);
+
+ /*
+ * Initializes the swizzler.
+ *
+ * @param dstInfo Output image information. Dimensions may have been
+ * adjusted if the image frame size does not match the size
+ * indicated in the header.
+ * @param zeroInit Indicates if destination memory is zero initialized.
+ */
+ SkCodec::Result initializeSwizzler(const SkImageInfo& dstInfo,
+ ZeroInitialized zeroInit);
+
+ /*
+ * @return kSuccess if the read is successful and kIncompleteInput if the
+ * read fails.
+ */
+ SkCodec::Result readRow();
+
+ /*
* This function cleans up the gif object after the decode completes
* It is used in a SkAutoTCallIProc template
*/
@@ -88,10 +154,21 @@
* @param stream the stream of image data
* @param gif pointer to library type that manages gif decode
* takes ownership
+ * @param transIndex The transparent index. An invalid value
+ * indicates that there is no transparent index.
*/
- SkGifCodec(const SkImageInfo& srcInfo, SkStream* stream, GifFileType* gif);
+ SkGifCodec(const SkImageInfo& srcInfo, SkStream* stream, GifFileType* gif, uint32_t transIndex);
SkAutoTCallVProc<GifFileType, CloseGif> fGif; // owned
+ SkAutoTDeleteArray<uint8_t> fSrcBuffer;
+ SkIRect fFrameDims;
+ const uint32_t fTransIndex;
+ uint32_t fFillIndex;
+ bool fFrameIsSubset;
+ SkAutoTDelete<SkSwizzler> fSwizzler;
+ SkAutoTUnref<SkColorTable> fColorTable;
+
+ friend class SkGifScanlineDecoder;
typedef SkCodec INHERITED;
};