/* * Copyright 2006 The Android Open Source Project * * Use of this source code is governed by a BSD-style license that can be * found in the LICENSE file. */ #include "SkImageDecoder.h" #include "SkColor.h" #include "SkColorPriv.h" #include "SkStream.h" #include "SkTemplates.h" #include "SkPackBits.h" #include "gif_lib.h" class SkGIFImageDecoder : public SkImageDecoder { public: virtual Format getFormat() const SK_OVERRIDE { return kGIF_Format; } protected: virtual bool onDecode(SkStream* stream, SkBitmap* bm, Mode mode) SK_OVERRIDE; private: typedef SkImageDecoder INHERITED; }; static const uint8_t gStartingIterlaceYValue[] = { 0, 4, 2, 1 }; static const uint8_t gDeltaIterlaceYValue[] = { 8, 8, 4, 2 }; /* Implement the GIF interlace algorithm in an iterator. 1) grab every 8th line beginning at 0 2) grab every 8th line beginning at 4 3) grab every 4th line beginning at 2 4) grab every 2nd line beginning at 1 */ class GifInterlaceIter { public: GifInterlaceIter(int height) : fHeight(height) { fStartYPtr = gStartingIterlaceYValue; fDeltaYPtr = gDeltaIterlaceYValue; fCurrY = *fStartYPtr++; fDeltaY = *fDeltaYPtr++; } int currY() const { SkASSERT(fStartYPtr); SkASSERT(fDeltaYPtr); return fCurrY; } void next() { SkASSERT(fStartYPtr); SkASSERT(fDeltaYPtr); int y = fCurrY + fDeltaY; // We went from an if statement to a while loop so that we iterate // through fStartYPtr until a valid row is found. This is so that images // that are smaller than 5x5 will not trash memory. while (y >= fHeight) { if (gStartingIterlaceYValue + SK_ARRAY_COUNT(gStartingIterlaceYValue) == fStartYPtr) { // we done SkDEBUGCODE(fStartYPtr = NULL;) SkDEBUGCODE(fDeltaYPtr = NULL;) y = 0; } else { y = *fStartYPtr++; fDeltaY = *fDeltaYPtr++; } } fCurrY = y; } private: const int fHeight; int fCurrY; int fDeltaY; const uint8_t* fStartYPtr; const uint8_t* fDeltaYPtr; }; /////////////////////////////////////////////////////////////////////////////// static int DecodeCallBackProc(GifFileType* fileType, GifByteType* out, int size) { SkStream* stream = (SkStream*) fileType->UserData; return (int) stream->read(out, size); } void CheckFreeExtension(SavedImage* Image) { if (Image->ExtensionBlocks) { #if GIFLIB_MAJOR < 5 FreeExtension(Image); #else GifFreeExtensions(&Image->ExtensionBlockCount, &Image->ExtensionBlocks); #endif } } // return NULL on failure static const ColorMapObject* find_colormap(const GifFileType* gif) { const ColorMapObject* cmap = gif->Image.ColorMap; if (NULL == cmap) { cmap = gif->SColorMap; } if (NULL == cmap) { // no colormap found return NULL; } // some sanity checks if (cmap && ((unsigned)cmap->ColorCount > 256 || cmap->ColorCount != (1 << cmap->BitsPerPixel))) { cmap = NULL; } return cmap; } // return -1 if not found (i.e. we're completely opaque) static int find_transpIndex(const SavedImage& image, int colorCount) { int transpIndex = -1; for (int i = 0; i < image.ExtensionBlockCount; ++i) { const ExtensionBlock* eb = image.ExtensionBlocks + i; if (eb->Function == 0xF9 && eb->ByteCount == 4) { if (eb->Bytes[0] & 1) { transpIndex = (unsigned char)eb->Bytes[3]; // check for valid transpIndex if (transpIndex >= colorCount) { transpIndex = -1; } break; } } } return transpIndex; } static bool error_return(GifFileType* gif, const SkBitmap& bm, const char msg[]) { #if 0 SkDebugf("libgif error <%s> bitmap [%d %d] pixels %p colortable %p\n", msg, bm.width(), bm.height(), bm.getPixels(), bm.getColorTable()); #endif return false; } bool SkGIFImageDecoder::onDecode(SkStream* sk_stream, SkBitmap* bm, Mode mode) { #if GIFLIB_MAJOR < 5 GifFileType* gif = DGifOpen(sk_stream, DecodeCallBackProc); #else GifFileType* gif = DGifOpen(sk_stream, DecodeCallBackProc, NULL); #endif if (NULL == gif) { return error_return(gif, *bm, "DGifOpen"); } SkAutoTCallIProc acp(gif); SavedImage temp_save; temp_save.ExtensionBlocks=NULL; temp_save.ExtensionBlockCount=0; SkAutoTCallVProc acp2(&temp_save); int width, height; GifRecordType recType; GifByteType *extData; #if GIFLIB_MAJOR >= 5 int extFunction; #endif int transpIndex = -1; // -1 means we don't have it (yet) do { if (DGifGetRecordType(gif, &recType) == GIF_ERROR) { return error_return(gif, *bm, "DGifGetRecordType"); } switch (recType) { case IMAGE_DESC_RECORD_TYPE: { if (DGifGetImageDesc(gif) == GIF_ERROR) { return error_return(gif, *bm, "IMAGE_DESC_RECORD_TYPE"); } if (gif->ImageCount < 1) { // sanity check return error_return(gif, *bm, "ImageCount < 1"); } width = gif->SWidth; height = gif->SHeight; if (width <= 0 || height <= 0 || !this->chooseFromOneChoice(SkBitmap::kIndex8_Config, width, height)) { return error_return(gif, *bm, "chooseFromOneChoice"); } bm->setConfig(SkBitmap::kIndex8_Config, width, height); if (SkImageDecoder::kDecodeBounds_Mode == mode) { return true; } SavedImage* image = &gif->SavedImages[gif->ImageCount-1]; const GifImageDesc& desc = image->ImageDesc; // check for valid descriptor if ( (desc.Top | desc.Left) < 0 || desc.Left + desc.Width > width || desc.Top + desc.Height > height) { return error_return(gif, *bm, "TopLeft"); } // now we decode the colortable int colorCount = 0; { const ColorMapObject* cmap = find_colormap(gif); if (NULL == cmap) { return error_return(gif, *bm, "null cmap"); } colorCount = cmap->ColorCount; SkColorTable* ctable = SkNEW_ARGS(SkColorTable, (colorCount)); SkPMColor* colorPtr = ctable->lockColors(); for (int index = 0; index < colorCount; index++) colorPtr[index] = SkPackARGB32(0xFF, cmap->Colors[index].Red, cmap->Colors[index].Green, cmap->Colors[index].Blue); transpIndex = find_transpIndex(temp_save, colorCount); if (transpIndex < 0) ctable->setFlags(ctable->getFlags() | SkColorTable::kColorsAreOpaque_Flag); else colorPtr[transpIndex] = 0; // ram in a transparent SkPMColor ctable->unlockColors(true); SkAutoUnref aurts(ctable); if (!this->allocPixelRef(bm, ctable)) { return error_return(gif, *bm, "allocPixelRef"); } } SkAutoLockPixels alp(*bm); // time to decode the scanlines // uint8_t* scanline = bm->getAddr8(0, 0); const int rowBytes = bm->rowBytes(); const int innerWidth = desc.Width; const int innerHeight = desc.Height; // abort if either inner dimension is <= 0 if (innerWidth <= 0 || innerHeight <= 0) { return error_return(gif, *bm, "non-pos inner width/height"); } // are we only a subset of the total bounds? if ((desc.Top | desc.Left) > 0 || innerWidth < width || innerHeight < height) { int fill; if (transpIndex >= 0) { fill = transpIndex; } else { fill = gif->SBackGroundColor; } // check for valid fill index/color if (static_cast(fill) >= static_cast(colorCount)) { fill = 0; } memset(scanline, fill, bm->getSize()); // bump our starting address scanline += desc.Top * rowBytes + desc.Left; } // now decode each scanline if (gif->Image.Interlace) { GifInterlaceIter iter(innerHeight); for (int y = 0; y < innerHeight; y++) { uint8_t* row = scanline + iter.currY() * rowBytes; if (DGifGetLine(gif, row, innerWidth) == GIF_ERROR) { return error_return(gif, *bm, "interlace DGifGetLine"); } iter.next(); } } else { // easy, non-interlace case for (int y = 0; y < innerHeight; y++) { if (DGifGetLine(gif, scanline, innerWidth) == GIF_ERROR) { return error_return(gif, *bm, "DGifGetLine"); } scanline += rowBytes; } } goto DONE; } break; case EXTENSION_RECORD_TYPE: #if GIFLIB_MAJOR < 5 if (DGifGetExtension(gif, &temp_save.Function, &extData) == GIF_ERROR) { #else if (DGifGetExtension(gif, &extFunction, &extData) == GIF_ERROR) { #endif return error_return(gif, *bm, "DGifGetExtension"); } while (extData != NULL) { /* Create an extension block with our data */ #if GIFLIB_MAJOR < 5 if (AddExtensionBlock(&temp_save, extData[0], &extData[1]) == GIF_ERROR) { #else if (GifAddExtensionBlock(&gif->ExtensionBlockCount, &gif->ExtensionBlocks, extFunction, extData[0], &extData[1]) == GIF_ERROR) { #endif return error_return(gif, *bm, "AddExtensionBlock"); } if (DGifGetExtensionNext(gif, &extData) == GIF_ERROR) { return error_return(gif, *bm, "DGifGetExtensionNext"); } #if GIFLIB_MAJOR < 5 temp_save.Function = 0; #endif } break; case TERMINATE_RECORD_TYPE: break; default: /* Should be trapped by DGifGetRecordType */ break; } } while (recType != TERMINATE_RECORD_TYPE); DONE: return true; } /////////////////////////////////////////////////////////////////////////////// DEFINE_DECODER_CREATOR(GIFImageDecoder); /////////////////////////////////////////////////////////////////////////////// static bool is_gif(SkStream* stream) { char buf[GIF_STAMP_LEN]; if (stream->read(buf, GIF_STAMP_LEN) == GIF_STAMP_LEN) { if (memcmp(GIF_STAMP, buf, GIF_STAMP_LEN) == 0 || memcmp(GIF87_STAMP, buf, GIF_STAMP_LEN) == 0 || memcmp(GIF89_STAMP, buf, GIF_STAMP_LEN) == 0) { return true; } } return false; } #include "SkTRegistry.h" static SkImageDecoder* sk_libgif_dfactory(SkStream* stream) { if (is_gif(stream)) { return SkNEW(SkGIFImageDecoder); } return NULL; } static SkTRegistry gReg(sk_libgif_dfactory); static SkImageDecoder::Format get_format_gif(SkStream* stream) { if (is_gif(stream)) { return SkImageDecoder::kGIF_Format; } return SkImageDecoder::kUnknown_Format; } static SkTRegistry gFormatReg(get_format_gif);