1 2 /* 3 * Copyright 2006 The Android Open Source Project 4 * 5 * Use of this source code is governed by a BSD-style license that can be 6 * found in the LICENSE file. 7 */ 8 9 10 #include "SkImageDecoder.h" 11 #include "SkColor.h" 12 #include "SkColorPriv.h" 13 #include "SkStream.h" 14 #include "SkTemplates.h" 15 #include "SkPackBits.h" 16 17 #include "gif_lib.h" 18 19 class SkGIFImageDecoder : public SkImageDecoder { 20 public: 21 virtual Format getFormat() const { 22 return kGIF_Format; 23 } 24 25 protected: 26 virtual bool onDecode(SkStream* stream, SkBitmap* bm, Mode mode); 27 }; 28 29 static const uint8_t gStartingIterlaceYValue[] = { 30 0, 4, 2, 1 31 }; 32 static const uint8_t gDeltaIterlaceYValue[] = { 33 8, 8, 4, 2 34 }; 35 36 /* Implement the GIF interlace algorithm in an iterator. 37 1) grab every 8th line beginning at 0 38 2) grab every 8th line beginning at 4 39 3) grab every 4th line beginning at 2 40 4) grab every 2nd line beginning at 1 41 */ 42 class GifInterlaceIter { 43 public: 44 GifInterlaceIter(int height) : fHeight(height) { 45 fStartYPtr = gStartingIterlaceYValue; 46 fDeltaYPtr = gDeltaIterlaceYValue; 47 48 fCurrY = *fStartYPtr++; 49 fDeltaY = *fDeltaYPtr++; 50 } 51 52 int currY() const { 53 SkASSERT(fStartYPtr); 54 SkASSERT(fDeltaYPtr); 55 return fCurrY; 56 } 57 58 void next() { 59 SkASSERT(fStartYPtr); 60 SkASSERT(fDeltaYPtr); 61 62 int y = fCurrY + fDeltaY; 63 // We went from an if statement to a while loop so that we iterate 64 // through fStartYPtr until a valid row is found. This is so that images 65 // that are smaller than 5x5 will not trash memory. 66 while (y >= fHeight) { 67 if (gStartingIterlaceYValue + 68 SK_ARRAY_COUNT(gStartingIterlaceYValue) == fStartYPtr) { 69 // we done 70 SkDEBUGCODE(fStartYPtr = NULL;) 71 SkDEBUGCODE(fDeltaYPtr = NULL;) 72 y = 0; 73 } else { 74 y = *fStartYPtr++; 75 fDeltaY = *fDeltaYPtr++; 76 } 77 } 78 fCurrY = y; 79 } 80 81 private: 82 const int fHeight; 83 int fCurrY; 84 int fDeltaY; 85 const uint8_t* fStartYPtr; 86 const uint8_t* fDeltaYPtr; 87 }; 88 89 /////////////////////////////////////////////////////////////////////////////// 90 91 //#define GIF_STAMP "GIF" /* First chars in file - GIF stamp. */ 92 //#define GIF_STAMP_LEN (sizeof(GIF_STAMP) - 1) 93 94 static int DecodeCallBackProc(GifFileType* fileType, GifByteType* out, 95 int size) { 96 SkStream* stream = (SkStream*) fileType->UserData; 97 return (int) stream->read(out, size); 98 } 99 100 void CheckFreeExtension(SavedImage* Image) { 101 if (Image->ExtensionBlocks) { 102 #if GIFLIB_MAJOR < 5 103 FreeExtension(Image); 104 #else 105 GifFreeExtensions(&Image->ExtensionBlockCount, &Image->ExtensionBlocks); 106 #endif 107 } 108 } 109 110 // return NULL on failure 111 static const ColorMapObject* find_colormap(const GifFileType* gif) { 112 const ColorMapObject* cmap = gif->Image.ColorMap; 113 if (NULL == cmap) { 114 cmap = gif->SColorMap; 115 } 116 117 if (NULL == cmap) { 118 // no colormap found 119 return NULL; 120 } 121 // some sanity checks 122 if (cmap && ((unsigned)cmap->ColorCount > 256 || 123 cmap->ColorCount != (1 << cmap->BitsPerPixel))) { 124 cmap = NULL; 125 } 126 return cmap; 127 } 128 129 // return -1 if not found (i.e. we're completely opaque) 130 static int find_transpIndex(const SavedImage& image, int colorCount) { 131 int transpIndex = -1; 132 for (int i = 0; i < image.ExtensionBlockCount; ++i) { 133 const ExtensionBlock* eb = image.ExtensionBlocks + i; 134 if (eb->Function == 0xF9 && eb->ByteCount == 4) { 135 if (eb->Bytes[0] & 1) { 136 transpIndex = (unsigned char)eb->Bytes[3]; 137 // check for valid transpIndex 138 if (transpIndex >= colorCount) { 139 transpIndex = -1; 140 } 141 break; 142 } 143 } 144 } 145 return transpIndex; 146 } 147 148 static bool error_return(GifFileType* gif, const SkBitmap& bm, 149 const char msg[]) { 150 #if 0 151 SkDebugf("libgif error <%s> bitmap [%d %d] pixels %p colortable %p\n", 152 msg, bm.width(), bm.height(), bm.getPixels(), bm.getColorTable()); 153 #endif 154 return false; 155 } 156 157 bool SkGIFImageDecoder::onDecode(SkStream* sk_stream, SkBitmap* bm, Mode mode) { 158 #if GIFLIB_MAJOR < 5 159 GifFileType* gif = DGifOpen(sk_stream, DecodeCallBackProc); 160 #else 161 GifFileType* gif = DGifOpen(sk_stream, DecodeCallBackProc, NULL); 162 #endif 163 if (NULL == gif) { 164 return error_return(gif, *bm, "DGifOpen"); 165 } 166 167 SkAutoTCallIProc<GifFileType, DGifCloseFile> acp(gif); 168 169 SavedImage temp_save; 170 temp_save.ExtensionBlocks=NULL; 171 temp_save.ExtensionBlockCount=0; 172 SkAutoTCallVProc<SavedImage, CheckFreeExtension> acp2(&temp_save); 173 174 int width, height; 175 GifRecordType recType; 176 GifByteType *extData; 177 #if GIFLIB_MAJOR >= 5 178 int extFunction; 179 #endif 180 int transpIndex = -1; // -1 means we don't have it (yet) 181 182 do { 183 if (DGifGetRecordType(gif, &recType) == GIF_ERROR) { 184 return error_return(gif, *bm, "DGifGetRecordType"); 185 } 186 187 switch (recType) { 188 case IMAGE_DESC_RECORD_TYPE: { 189 if (DGifGetImageDesc(gif) == GIF_ERROR) { 190 return error_return(gif, *bm, "IMAGE_DESC_RECORD_TYPE"); 191 } 192 193 if (gif->ImageCount < 1) { // sanity check 194 return error_return(gif, *bm, "ImageCount < 1"); 195 } 196 197 width = gif->SWidth; 198 height = gif->SHeight; 199 if (width <= 0 || height <= 0 || 200 !this->chooseFromOneChoice(SkBitmap::kIndex8_Config, 201 width, height)) { 202 return error_return(gif, *bm, "chooseFromOneChoice"); 203 } 204 205 if (SkImageDecoder::kDecodeBounds_Mode == mode) { 206 bm->setConfig(SkBitmap::kIndex8_Config, width, height); 207 return true; 208 } 209 #ifdef SK_BUILD_FOR_ANDROID 210 // No Bitmap reuse supported for this format 211 if (!bm->isNull()) { 212 return false; 213 } 214 #endif 215 216 bm->setConfig(SkBitmap::kIndex8_Config, width, height); 217 SavedImage* image = &gif->SavedImages[gif->ImageCount-1]; 218 const GifImageDesc& desc = image->ImageDesc; 219 220 // check for valid descriptor 221 if ( (desc.Top | desc.Left) < 0 || 222 desc.Left + desc.Width > width || 223 desc.Top + desc.Height > height) { 224 return error_return(gif, *bm, "TopLeft"); 225 } 226 227 // now we decode the colortable 228 int colorCount = 0; 229 { 230 const ColorMapObject* cmap = find_colormap(gif); 231 if (NULL == cmap) { 232 return error_return(gif, *bm, "null cmap"); 233 } 234 235 colorCount = cmap->ColorCount; 236 SkColorTable* ctable = SkNEW_ARGS(SkColorTable, (colorCount)); 237 SkPMColor* colorPtr = ctable->lockColors(); 238 for (int index = 0; index < colorCount; index++) 239 colorPtr[index] = SkPackARGB32(0xFF, 240 cmap->Colors[index].Red, 241 cmap->Colors[index].Green, 242 cmap->Colors[index].Blue); 243 244 transpIndex = find_transpIndex(temp_save, colorCount); 245 if (transpIndex < 0) 246 ctable->setFlags(ctable->getFlags() | SkColorTable::kColorsAreOpaque_Flag); 247 else 248 colorPtr[transpIndex] = 0; // ram in a transparent SkPMColor 249 ctable->unlockColors(true); 250 251 SkAutoUnref aurts(ctable); 252 if (!this->allocPixelRef(bm, ctable)) { 253 return error_return(gif, *bm, "allocPixelRef"); 254 } 255 } 256 257 SkAutoLockPixels alp(*bm); 258 259 // time to decode the scanlines 260 // 261 uint8_t* scanline = bm->getAddr8(0, 0); 262 const int rowBytes = bm->rowBytes(); 263 const int innerWidth = desc.Width; 264 const int innerHeight = desc.Height; 265 266 // abort if either inner dimension is <= 0 267 if (innerWidth <= 0 || innerHeight <= 0) { 268 return error_return(gif, *bm, "non-pos inner width/height"); 269 } 270 271 // are we only a subset of the total bounds? 272 if ((desc.Top | desc.Left) > 0 || 273 innerWidth < width || innerHeight < height) 274 { 275 int fill; 276 if (transpIndex >= 0) { 277 fill = transpIndex; 278 } else { 279 fill = gif->SBackGroundColor; 280 } 281 // check for valid fill index/color 282 if (static_cast<unsigned>(fill) >= 283 static_cast<unsigned>(colorCount)) { 284 fill = 0; 285 } 286 memset(scanline, fill, bm->getSize()); 287 // bump our starting address 288 scanline += desc.Top * rowBytes + desc.Left; 289 } 290 291 // now decode each scanline 292 if (gif->Image.Interlace) 293 { 294 GifInterlaceIter iter(innerHeight); 295 for (int y = 0; y < innerHeight; y++) 296 { 297 uint8_t* row = scanline + iter.currY() * rowBytes; 298 if (DGifGetLine(gif, row, innerWidth) == GIF_ERROR) { 299 return error_return(gif, *bm, "interlace DGifGetLine"); 300 } 301 iter.next(); 302 } 303 } 304 else 305 { 306 // easy, non-interlace case 307 for (int y = 0; y < innerHeight; y++) { 308 if (DGifGetLine(gif, scanline, innerWidth) == GIF_ERROR) { 309 return error_return(gif, *bm, "DGifGetLine"); 310 } 311 scanline += rowBytes; 312 } 313 } 314 goto DONE; 315 } break; 316 317 case EXTENSION_RECORD_TYPE: 318 #if GIFLIB_MAJOR < 5 319 if (DGifGetExtension(gif, &temp_save.Function, 320 &extData) == GIF_ERROR) { 321 #else 322 if (DGifGetExtension(gif, &extFunction, &extData) == GIF_ERROR) { 323 #endif 324 return error_return(gif, *bm, "DGifGetExtension"); 325 } 326 327 while (extData != NULL) { 328 /* Create an extension block with our data */ 329 #if GIFLIB_MAJOR < 5 330 if (AddExtensionBlock(&temp_save, extData[0], 331 &extData[1]) == GIF_ERROR) { 332 #else 333 if (GifAddExtensionBlock(&gif->ExtensionBlockCount, 334 &gif->ExtensionBlocks, 335 extFunction, 336 extData[0], 337 &extData[1]) == GIF_ERROR) { 338 #endif 339 return error_return(gif, *bm, "AddExtensionBlock"); 340 } 341 if (DGifGetExtensionNext(gif, &extData) == GIF_ERROR) { 342 return error_return(gif, *bm, "DGifGetExtensionNext"); 343 } 344 #if GIFLIB_MAJOR < 5 345 temp_save.Function = 0; 346 #endif 347 } 348 break; 349 350 case TERMINATE_RECORD_TYPE: 351 break; 352 353 default: /* Should be trapped by DGifGetRecordType */ 354 break; 355 } 356 } while (recType != TERMINATE_RECORD_TYPE); 357 358 DONE: 359 return true; 360 } 361 362 /////////////////////////////////////////////////////////////////////////////// 363 DEFINE_DECODER_CREATOR(GIFImageDecoder); 364 /////////////////////////////////////////////////////////////////////////////// 365 366 #include "SkTRegistry.h" 367 368 static SkImageDecoder* sk_libgif_dfactory(SkStream* stream) { 369 char buf[GIF_STAMP_LEN]; 370 if (stream->read(buf, GIF_STAMP_LEN) == GIF_STAMP_LEN) { 371 if (memcmp(GIF_STAMP, buf, GIF_STAMP_LEN) == 0 || 372 memcmp(GIF87_STAMP, buf, GIF_STAMP_LEN) == 0 || 373 memcmp(GIF89_STAMP, buf, GIF_STAMP_LEN) == 0) { 374 return SkNEW(SkGIFImageDecoder); 375 } 376 } 377 return NULL; 378 } 379 380 static SkTRegistry<SkImageDecoder*, SkStream*> gReg(sk_libgif_dfactory); 381
