1 /* 2 * Copyright 2006 The Android Open Source Project 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #include "SkColor.h" 9 #include "SkColorPriv.h" 10 #include "SkColorTable.h" 11 #include "SkImageDecoder.h" 12 #include "SkRTConf.h" 13 #include "SkScaledBitmapSampler.h" 14 #include "SkStream.h" 15 #include "SkTemplates.h" 16 #include "SkUtils.h" 17 18 #include "gif_lib.h" 19 20 class SkGIFImageDecoder : public SkImageDecoder { 21 public: 22 virtual Format getFormat() const SK_OVERRIDE { 23 return kGIF_Format; 24 } 25 26 protected: 27 virtual bool onDecode(SkStream* stream, SkBitmap* bm, Mode mode) SK_OVERRIDE; 28 29 private: 30 typedef SkImageDecoder INHERITED; 31 }; 32 33 static const uint8_t gStartingIterlaceYValue[] = { 34 0, 4, 2, 1 35 }; 36 static const uint8_t gDeltaIterlaceYValue[] = { 37 8, 8, 4, 2 38 }; 39 40 SK_CONF_DECLARE(bool, c_suppressGIFImageDecoderWarnings, 41 "images.gif.suppressDecoderWarnings", true, 42 "Suppress GIF warnings and errors when calling image decode " 43 "functions."); 44 45 46 /* Implement the GIF interlace algorithm in an iterator. 47 1) grab every 8th line beginning at 0 48 2) grab every 8th line beginning at 4 49 3) grab every 4th line beginning at 2 50 4) grab every 2nd line beginning at 1 51 */ 52 class GifInterlaceIter { 53 public: 54 GifInterlaceIter(int height) : fHeight(height) { 55 fStartYPtr = gStartingIterlaceYValue; 56 fDeltaYPtr = gDeltaIterlaceYValue; 57 58 fCurrY = *fStartYPtr++; 59 fDeltaY = *fDeltaYPtr++; 60 } 61 62 int currY() const { 63 SkASSERT(fStartYPtr); 64 SkASSERT(fDeltaYPtr); 65 return fCurrY; 66 } 67 68 void next() { 69 SkASSERT(fStartYPtr); 70 SkASSERT(fDeltaYPtr); 71 72 int y = fCurrY + fDeltaY; 73 // We went from an if statement to a while loop so that we iterate 74 // through fStartYPtr until a valid row is found. This is so that images 75 // that are smaller than 5x5 will not trash memory. 76 while (y >= fHeight) { 77 if (gStartingIterlaceYValue + 78 SK_ARRAY_COUNT(gStartingIterlaceYValue) == fStartYPtr) { 79 // we done 80 SkDEBUGCODE(fStartYPtr = NULL;) 81 SkDEBUGCODE(fDeltaYPtr = NULL;) 82 y = 0; 83 } else { 84 y = *fStartYPtr++; 85 fDeltaY = *fDeltaYPtr++; 86 } 87 } 88 fCurrY = y; 89 } 90 91 private: 92 const int fHeight; 93 int fCurrY; 94 int fDeltaY; 95 const uint8_t* fStartYPtr; 96 const uint8_t* fDeltaYPtr; 97 }; 98 99 /////////////////////////////////////////////////////////////////////////////// 100 101 static int DecodeCallBackProc(GifFileType* fileType, GifByteType* out, 102 int size) { 103 SkStream* stream = (SkStream*) fileType->UserData; 104 return (int) stream->read(out, size); 105 } 106 107 void CheckFreeExtension(SavedImage* Image) { 108 if (Image->ExtensionBlocks) { 109 #if GIFLIB_MAJOR < 5 110 FreeExtension(Image); 111 #else 112 GifFreeExtensions(&Image->ExtensionBlockCount, &Image->ExtensionBlocks); 113 #endif 114 } 115 } 116 117 // return NULL on failure 118 static const ColorMapObject* find_colormap(const GifFileType* gif) { 119 const ColorMapObject* cmap = gif->Image.ColorMap; 120 if (NULL == cmap) { 121 cmap = gif->SColorMap; 122 } 123 124 if (NULL == cmap) { 125 // no colormap found 126 return NULL; 127 } 128 // some sanity checks 129 if (cmap && ((unsigned)cmap->ColorCount > 256 || 130 cmap->ColorCount != (1 << cmap->BitsPerPixel))) { 131 cmap = NULL; 132 } 133 return cmap; 134 } 135 136 // return -1 if not found (i.e. we're completely opaque) 137 static int find_transpIndex(const SavedImage& image, int colorCount) { 138 int transpIndex = -1; 139 for (int i = 0; i < image.ExtensionBlockCount; ++i) { 140 const ExtensionBlock* eb = image.ExtensionBlocks + i; 141 if (eb->Function == 0xF9 && eb->ByteCount == 4) { 142 if (eb->Bytes[0] & 1) { 143 transpIndex = (unsigned char)eb->Bytes[3]; 144 // check for valid transpIndex 145 if (transpIndex >= colorCount) { 146 transpIndex = -1; 147 } 148 break; 149 } 150 } 151 } 152 return transpIndex; 153 } 154 155 static bool error_return(const SkBitmap& bm, const char msg[]) { 156 if (!c_suppressGIFImageDecoderWarnings) { 157 SkDebugf("libgif error [%s] bitmap [%d %d] pixels %p colortable %p\n", 158 msg, bm.width(), bm.height(), bm.getPixels(), 159 bm.getColorTable()); 160 } 161 return false; 162 } 163 static void gif_warning(const SkBitmap& bm, const char msg[]) { 164 if (!c_suppressGIFImageDecoderWarnings) { 165 SkDebugf("libgif warning [%s] bitmap [%d %d] pixels %p colortable %p\n", 166 msg, bm.width(), bm.height(), bm.getPixels(), 167 bm.getColorTable()); 168 } 169 } 170 171 /** 172 * Skip rows in the source gif image. 173 * @param gif Source image. 174 * @param dst Scratch output needed by gif library call. Must be >= width bytes. 175 * @param width Bytes per row in the source image. 176 * @param rowsToSkip Number of rows to skip. 177 * @return True on success, false on GIF_ERROR. 178 */ 179 static bool skip_src_rows(GifFileType* gif, uint8_t* dst, int width, int rowsToSkip) { 180 for (int i = 0; i < rowsToSkip; i++) { 181 if (DGifGetLine(gif, dst, width) == GIF_ERROR) { 182 return false; 183 } 184 } 185 return true; 186 } 187 188 bool SkGIFImageDecoder::onDecode(SkStream* sk_stream, SkBitmap* bm, Mode mode) { 189 #if GIFLIB_MAJOR < 5 190 GifFileType* gif = DGifOpen(sk_stream, DecodeCallBackProc); 191 #else 192 GifFileType* gif = DGifOpen(sk_stream, DecodeCallBackProc, NULL); 193 #endif 194 if (NULL == gif) { 195 return error_return(*bm, "DGifOpen"); 196 } 197 198 SkAutoTCallIProc<GifFileType, DGifCloseFile> acp(gif); 199 200 SavedImage temp_save; 201 temp_save.ExtensionBlocks=NULL; 202 temp_save.ExtensionBlockCount=0; 203 SkAutoTCallVProc<SavedImage, CheckFreeExtension> acp2(&temp_save); 204 205 int width, height; 206 GifRecordType recType; 207 GifByteType *extData; 208 #if GIFLIB_MAJOR >= 5 209 int extFunction; 210 #endif 211 int transpIndex = -1; // -1 means we don't have it (yet) 212 int fillIndex = gif->SBackGroundColor; 213 214 do { 215 if (DGifGetRecordType(gif, &recType) == GIF_ERROR) { 216 return error_return(*bm, "DGifGetRecordType"); 217 } 218 219 switch (recType) { 220 case IMAGE_DESC_RECORD_TYPE: { 221 if (DGifGetImageDesc(gif) == GIF_ERROR) { 222 return error_return(*bm, "IMAGE_DESC_RECORD_TYPE"); 223 } 224 225 if (gif->ImageCount < 1) { // sanity check 226 return error_return(*bm, "ImageCount < 1"); 227 } 228 229 width = gif->SWidth; 230 height = gif->SHeight; 231 232 SavedImage* image = &gif->SavedImages[gif->ImageCount-1]; 233 const GifImageDesc& desc = image->ImageDesc; 234 235 int imageLeft = desc.Left; 236 int imageTop = desc.Top; 237 const int innerWidth = desc.Width; 238 const int innerHeight = desc.Height; 239 if (innerWidth <= 0 || innerHeight <= 0) { 240 return error_return(*bm, "invalid dimensions"); 241 } 242 243 // check for valid descriptor 244 if (innerWidth > width) { 245 gif_warning(*bm, "image too wide, expanding output to size"); 246 width = innerWidth; 247 imageLeft = 0; 248 } else if (imageLeft + innerWidth > width) { 249 gif_warning(*bm, "shifting image left to fit"); 250 imageLeft = width - innerWidth; 251 } else if (imageLeft < 0) { 252 gif_warning(*bm, "shifting image right to fit"); 253 imageLeft = 0; 254 } 255 256 257 if (innerHeight > height) { 258 gif_warning(*bm, "image too tall, expanding output to size"); 259 height = innerHeight; 260 imageTop = 0; 261 } else if (imageTop + innerHeight > height) { 262 gif_warning(*bm, "shifting image up to fit"); 263 imageTop = height - innerHeight; 264 } else if (imageTop < 0) { 265 gif_warning(*bm, "shifting image down to fit"); 266 imageTop = 0; 267 } 268 269 // FIXME: We could give the caller a choice of images or configs. 270 if (!this->chooseFromOneChoice(SkBitmap::kIndex8_Config, width, height)) { 271 return error_return(*bm, "chooseFromOneChoice"); 272 } 273 274 SkScaledBitmapSampler sampler(width, height, this->getSampleSize()); 275 276 bm->setConfig(SkBitmap::kIndex8_Config, sampler.scaledWidth(), 277 sampler.scaledHeight()); 278 279 if (SkImageDecoder::kDecodeBounds_Mode == mode) { 280 return true; 281 } 282 283 284 // now we decode the colortable 285 int colorCount = 0; 286 { 287 // Declare colorPtr here for scope. 288 SkPMColor colorPtr[256]; // storage for worst-case 289 const ColorMapObject* cmap = find_colormap(gif); 290 SkAlphaType alphaType = kOpaque_SkAlphaType; 291 if (cmap != NULL) { 292 colorCount = cmap->ColorCount; 293 if (colorCount > 256) { 294 colorCount = 256; // our kIndex8 can't support more 295 } 296 for (int index = 0; index < colorCount; index++) { 297 colorPtr[index] = SkPackARGB32(0xFF, 298 cmap->Colors[index].Red, 299 cmap->Colors[index].Green, 300 cmap->Colors[index].Blue); 301 } 302 } else { 303 // find_colormap() returned NULL. Some (rare, broken) 304 // GIFs don't have a color table, so we force one. 305 gif_warning(*bm, "missing colormap"); 306 colorCount = 256; 307 sk_memset32(colorPtr, SK_ColorWHITE, colorCount); 308 } 309 transpIndex = find_transpIndex(temp_save, colorCount); 310 if (transpIndex >= 0) { 311 colorPtr[transpIndex] = SK_ColorTRANSPARENT; // ram in a transparent SkPMColor 312 alphaType = kPremul_SkAlphaType; 313 fillIndex = transpIndex; 314 } else if (fillIndex >= colorCount) { 315 // gif->SBackGroundColor should be less than colorCount. 316 fillIndex = 0; // If not, fix it. 317 } 318 319 SkAutoTUnref<SkColorTable> ctable(SkNEW_ARGS(SkColorTable, 320 (colorPtr, colorCount, 321 alphaType))); 322 if (!this->allocPixelRef(bm, ctable)) { 323 return error_return(*bm, "allocPixelRef"); 324 } 325 } 326 327 // abort if either inner dimension is <= 0 328 if (innerWidth <= 0 || innerHeight <= 0) { 329 return error_return(*bm, "non-pos inner width/height"); 330 } 331 332 SkAutoLockPixels alp(*bm); 333 334 SkAutoMalloc storage(innerWidth); 335 uint8_t* scanline = (uint8_t*) storage.get(); 336 337 // GIF has an option to store the scanlines of an image, plus a larger background, 338 // filled by a fill color. In this case, we will use a subset of the larger bitmap 339 // for sampling. 340 SkBitmap subset; 341 SkBitmap* workingBitmap; 342 // are we only a subset of the total bounds? 343 if ((imageTop | imageLeft) > 0 || 344 innerWidth < width || innerHeight < height) { 345 // Fill the background. 346 memset(bm->getPixels(), fillIndex, bm->getSize()); 347 348 // Create a subset of the bitmap. 349 SkIRect subsetRect(SkIRect::MakeXYWH(imageLeft / sampler.srcDX(), 350 imageTop / sampler.srcDY(), 351 innerWidth / sampler.srcDX(), 352 innerHeight / sampler.srcDY())); 353 if (!bm->extractSubset(&subset, subsetRect)) { 354 return error_return(*bm, "Extract failed."); 355 } 356 // Update the sampler. We'll now be only sampling into the subset. 357 sampler = SkScaledBitmapSampler(innerWidth, innerHeight, this->getSampleSize()); 358 workingBitmap = ⊂ 359 } else { 360 workingBitmap = bm; 361 } 362 363 // bm is already locked, but if we had to take a subset, it must be locked also, 364 // so that getPixels() will point to its pixels. 365 SkAutoLockPixels alpWorking(*workingBitmap); 366 367 if (!sampler.begin(workingBitmap, SkScaledBitmapSampler::kIndex, *this)) { 368 return error_return(*bm, "Sampler failed to begin."); 369 } 370 371 // now decode each scanline 372 if (gif->Image.Interlace) { 373 // Iterate over the height of the source data. The sampler will 374 // take care of skipping unneeded rows. 375 GifInterlaceIter iter(innerHeight); 376 for (int y = 0; y < innerHeight; y++) { 377 if (DGifGetLine(gif, scanline, innerWidth) == GIF_ERROR) { 378 gif_warning(*bm, "interlace DGifGetLine"); 379 memset(scanline, fillIndex, innerWidth); 380 for (; y < innerHeight; y++) { 381 sampler.sampleInterlaced(scanline, iter.currY()); 382 iter.next(); 383 } 384 return true; 385 } 386 sampler.sampleInterlaced(scanline, iter.currY()); 387 iter.next(); 388 } 389 } else { 390 // easy, non-interlace case 391 const int outHeight = workingBitmap->height(); 392 skip_src_rows(gif, scanline, innerWidth, sampler.srcY0()); 393 for (int y = 0; y < outHeight; y++) { 394 if (DGifGetLine(gif, scanline, innerWidth) == GIF_ERROR) { 395 gif_warning(*bm, "DGifGetLine"); 396 memset(scanline, fillIndex, innerWidth); 397 for (; y < outHeight; y++) { 398 sampler.next(scanline); 399 } 400 return true; 401 } 402 // scanline now contains the raw data. Sample it. 403 sampler.next(scanline); 404 if (y < outHeight - 1) { 405 skip_src_rows(gif, scanline, innerWidth, sampler.srcDY() - 1); 406 } 407 } 408 // skip the rest of the rows (if any) 409 int read = (outHeight - 1) * sampler.srcDY() + sampler.srcY0() + 1; 410 SkASSERT(read <= innerHeight); 411 skip_src_rows(gif, scanline, innerWidth, innerHeight - read); 412 } 413 return true; 414 } break; 415 416 case EXTENSION_RECORD_TYPE: 417 #if GIFLIB_MAJOR < 5 418 if (DGifGetExtension(gif, &temp_save.Function, 419 &extData) == GIF_ERROR) { 420 #else 421 if (DGifGetExtension(gif, &extFunction, &extData) == GIF_ERROR) { 422 #endif 423 return error_return(*bm, "DGifGetExtension"); 424 } 425 426 while (extData != NULL) { 427 /* Create an extension block with our data */ 428 #if GIFLIB_MAJOR < 5 429 if (AddExtensionBlock(&temp_save, extData[0], 430 &extData[1]) == GIF_ERROR) { 431 #else 432 if (GifAddExtensionBlock(&gif->ExtensionBlockCount, 433 &gif->ExtensionBlocks, 434 extFunction, 435 extData[0], 436 &extData[1]) == GIF_ERROR) { 437 #endif 438 return error_return(*bm, "AddExtensionBlock"); 439 } 440 if (DGifGetExtensionNext(gif, &extData) == GIF_ERROR) { 441 return error_return(*bm, "DGifGetExtensionNext"); 442 } 443 #if GIFLIB_MAJOR < 5 444 temp_save.Function = 0; 445 #endif 446 } 447 break; 448 449 case TERMINATE_RECORD_TYPE: 450 break; 451 452 default: /* Should be trapped by DGifGetRecordType */ 453 break; 454 } 455 } while (recType != TERMINATE_RECORD_TYPE); 456 457 return true; 458 } 459 460 /////////////////////////////////////////////////////////////////////////////// 461 DEFINE_DECODER_CREATOR(GIFImageDecoder); 462 /////////////////////////////////////////////////////////////////////////////// 463 464 static bool is_gif(SkStreamRewindable* stream) { 465 char buf[GIF_STAMP_LEN]; 466 if (stream->read(buf, GIF_STAMP_LEN) == GIF_STAMP_LEN) { 467 if (memcmp(GIF_STAMP, buf, GIF_STAMP_LEN) == 0 || 468 memcmp(GIF87_STAMP, buf, GIF_STAMP_LEN) == 0 || 469 memcmp(GIF89_STAMP, buf, GIF_STAMP_LEN) == 0) { 470 return true; 471 } 472 } 473 return false; 474 } 475 476 static SkImageDecoder* sk_libgif_dfactory(SkStreamRewindable* stream) { 477 if (is_gif(stream)) { 478 return SkNEW(SkGIFImageDecoder); 479 } 480 return NULL; 481 } 482 483 static SkImageDecoder_DecodeReg gReg(sk_libgif_dfactory); 484 485 static SkImageDecoder::Format get_format_gif(SkStreamRewindable* stream) { 486 if (is_gif(stream)) { 487 return SkImageDecoder::kGIF_Format; 488 } 489 return SkImageDecoder::kUnknown_Format; 490 } 491 492 static SkImageDecoder_FormatReg gFormatReg(get_format_gif); 493