The Tor Browser / file comparison

comparison: gfx/skia/trunk/src/images/SkImageDecoder_libgif.cpp

gfx/skia/trunk/src/images/SkImageDecoder_libgif.cpp

branch
TOR_BUG_3246
changeset 7
129ffea94266
equal deleted inserted replaced
-1:000000000000 0:e9e043df2322
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 /**
189 * GIFs with fewer then 256 color entries will sometimes index out of
190 * bounds of the color table (this is malformed, but libgif does not
191 * check sicne it is rare). This function checks for this error and
192 * fixes it. This makes the output image consistantly deterministic.
193 */
194 static void sanitize_indexed_bitmap(SkBitmap* bm) {
195 if ((SkBitmap::kIndex8_Config == bm->config()) && !(bm->empty())) {
196 SkAutoLockPixels alp(*bm);
197 if (NULL != bm->getPixels()) {
198 SkColorTable* ct = bm->getColorTable(); // Index8 must have it.
199 SkASSERT(ct != NULL);
200 uint32_t count = ct->count();
201 SkASSERT(count > 0);
202 SkASSERT(count <= 0x100);
203 if (count != 0x100) { // Full colortables can't go wrong.
204 // Count is a power of 2; asserted elsewhere.
205 uint8_t byteMask = (~(count - 1));
206 bool warning = false;
207 uint8_t* addr = static_cast<uint8_t*>(bm->getPixels());
208 int height = bm->height();
209 int width = bm->width();
210 size_t rowBytes = bm->rowBytes();
211 while (--height >= 0) {
212 uint8_t* ptr = addr;
213 int x = width;
214 while (--x >= 0) {
215 if (0 != ((*ptr) & byteMask)) {
216 warning = true;
217 *ptr = 0;
218 }
219 ++ptr;
220 }
221 addr += rowBytes;
222 }
223 if (warning) {
224 gif_warning(*bm, "Index out of bounds.");
225 }
226 }
227 }
228 }
229 }
230
231 bool SkGIFImageDecoder::onDecode(SkStream* sk_stream, SkBitmap* bm, Mode mode) {
232 #if GIFLIB_MAJOR < 5
233 GifFileType* gif = DGifOpen(sk_stream, DecodeCallBackProc);
234 #else
235 GifFileType* gif = DGifOpen(sk_stream, DecodeCallBackProc, NULL);
236 #endif
237 if (NULL == gif) {
238 return error_return(*bm, "DGifOpen");
239 }
240
241 SkAutoTCallIProc<GifFileType, DGifCloseFile> acp(gif);
242
243 SavedImage temp_save;
244 temp_save.ExtensionBlocks=NULL;
245 temp_save.ExtensionBlockCount=0;
246 SkAutoTCallVProc<SavedImage, CheckFreeExtension> acp2(&temp_save);
247
248 int width, height;
249 GifRecordType recType;
250 GifByteType *extData;
251 #if GIFLIB_MAJOR >= 5
252 int extFunction;
253 #endif
254 int transpIndex = -1; // -1 means we don't have it (yet)
255 int fillIndex = gif->SBackGroundColor;
256
257 do {
258 if (DGifGetRecordType(gif, &recType) == GIF_ERROR) {
259 return error_return(*bm, "DGifGetRecordType");
260 }
261
262 switch (recType) {
263 case IMAGE_DESC_RECORD_TYPE: {
264 if (DGifGetImageDesc(gif) == GIF_ERROR) {
265 return error_return(*bm, "IMAGE_DESC_RECORD_TYPE");
266 }
267
268 if (gif->ImageCount < 1) { // sanity check
269 return error_return(*bm, "ImageCount < 1");
270 }
271
272 width = gif->SWidth;
273 height = gif->SHeight;
274
275 SavedImage* image = &gif->SavedImages[gif->ImageCount-1];
276 const GifImageDesc& desc = image->ImageDesc;
277
278 int imageLeft = desc.Left;
279 int imageTop = desc.Top;
280 const int innerWidth = desc.Width;
281 const int innerHeight = desc.Height;
282 if (innerWidth <= 0 || innerHeight <= 0) {
283 return error_return(*bm, "invalid dimensions");
284 }
285
286 // check for valid descriptor
287 if (innerWidth > width) {
288 gif_warning(*bm, "image too wide, expanding output to size");
289 width = innerWidth;
290 imageLeft = 0;
291 } else if (imageLeft + innerWidth > width) {
292 gif_warning(*bm, "shifting image left to fit");
293 imageLeft = width - innerWidth;
294 } else if (imageLeft < 0) {
295 gif_warning(*bm, "shifting image right to fit");
296 imageLeft = 0;
297 }
298
299
300 if (innerHeight > height) {
301 gif_warning(*bm, "image too tall, expanding output to size");
302 height = innerHeight;
303 imageTop = 0;
304 } else if (imageTop + innerHeight > height) {
305 gif_warning(*bm, "shifting image up to fit");
306 imageTop = height - innerHeight;
307 } else if (imageTop < 0) {
308 gif_warning(*bm, "shifting image down to fit");
309 imageTop = 0;
310 }
311
312 // FIXME: We could give the caller a choice of images or configs.
313 if (!this->chooseFromOneChoice(SkBitmap::kIndex8_Config, width, height)) {
314 return error_return(*bm, "chooseFromOneChoice");
315 }
316
317 SkScaledBitmapSampler sampler(width, height, this->getSampleSize());
318
319 bm->setConfig(SkBitmap::kIndex8_Config, sampler.scaledWidth(),
320 sampler.scaledHeight());
321
322 if (SkImageDecoder::kDecodeBounds_Mode == mode) {
323 return true;
324 }
325
326
327 // now we decode the colortable
328 int colorCount = 0;
329 {
330 // Declare colorPtr here for scope.
331 SkPMColor colorPtr[256]; // storage for worst-case
332 const ColorMapObject* cmap = find_colormap(gif);
333 SkAlphaType alphaType = kOpaque_SkAlphaType;
334 if (cmap != NULL) {
335 SkASSERT(cmap->ColorCount == (1 << (cmap->BitsPerPixel)));
336 colorCount = cmap->ColorCount;
337 if (colorCount > 256) {
338 colorCount = 256; // our kIndex8 can't support more
339 }
340 for (int index = 0; index < colorCount; index++) {
341 colorPtr[index] = SkPackARGB32(0xFF,
342 cmap->Colors[index].Red,
343 cmap->Colors[index].Green,
344 cmap->Colors[index].Blue);
345 }
346 } else {
347 // find_colormap() returned NULL. Some (rare, broken)
348 // GIFs don't have a color table, so we force one.
349 gif_warning(*bm, "missing colormap");
350 colorCount = 256;
351 sk_memset32(colorPtr, SK_ColorWHITE, colorCount);
352 }
353 transpIndex = find_transpIndex(temp_save, colorCount);
354 if (transpIndex >= 0) {
355 colorPtr[transpIndex] = SK_ColorTRANSPARENT; // ram in a transparent SkPMColor
356 alphaType = kPremul_SkAlphaType;
357 fillIndex = transpIndex;
358 } else if (fillIndex >= colorCount) {
359 // gif->SBackGroundColor should be less than colorCount.
360 fillIndex = 0; // If not, fix it.
361 }
362
363 SkAutoTUnref<SkColorTable> ctable(SkNEW_ARGS(SkColorTable,
364 (colorPtr, colorCount,
365 alphaType)));
366 if (!this->allocPixelRef(bm, ctable)) {
367 return error_return(*bm, "allocPixelRef");
368 }
369 }
370
371 // abort if either inner dimension is <= 0
372 if (innerWidth <= 0 || innerHeight <= 0) {
373 return error_return(*bm, "non-pos inner width/height");
374 }
375
376 SkAutoLockPixels alp(*bm);
377
378 SkAutoMalloc storage(innerWidth);
379 uint8_t* scanline = (uint8_t*) storage.get();
380
381 // GIF has an option to store the scanlines of an image, plus a larger background,
382 // filled by a fill color. In this case, we will use a subset of the larger bitmap
383 // for sampling.
384 SkBitmap subset;
385 SkBitmap* workingBitmap;
386 // are we only a subset of the total bounds?
387 if ((imageTop | imageLeft) > 0 ||
388 innerWidth < width || innerHeight < height) {
389 // Fill the background.
390 memset(bm->getPixels(), fillIndex, bm->getSize());
391
392 // Create a subset of the bitmap.
393 SkIRect subsetRect(SkIRect::MakeXYWH(imageLeft / sampler.srcDX(),
394 imageTop / sampler.srcDY(),
395 innerWidth / sampler.srcDX(),
396 innerHeight / sampler.srcDY()));
397 if (!bm->extractSubset(&subset, subsetRect)) {
398 return error_return(*bm, "Extract failed.");
399 }
400 // Update the sampler. We'll now be only sampling into the subset.
401 sampler = SkScaledBitmapSampler(innerWidth, innerHeight, this->getSampleSize());
402 workingBitmap = &subset;
403 } else {
404 workingBitmap = bm;
405 }
406
407 // bm is already locked, but if we had to take a subset, it must be locked also,
408 // so that getPixels() will point to its pixels.
409 SkAutoLockPixels alpWorking(*workingBitmap);
410
411 if (!sampler.begin(workingBitmap, SkScaledBitmapSampler::kIndex, *this)) {
412 return error_return(*bm, "Sampler failed to begin.");
413 }
414
415 // now decode each scanline
416 if (gif->Image.Interlace) {
417 // Iterate over the height of the source data. The sampler will
418 // take care of skipping unneeded rows.
419 GifInterlaceIter iter(innerHeight);
420 for (int y = 0; y < innerHeight; y++) {
421 if (DGifGetLine(gif, scanline, innerWidth) == GIF_ERROR) {
422 gif_warning(*bm, "interlace DGifGetLine");
423 memset(scanline, fillIndex, innerWidth);
424 for (; y < innerHeight; y++) {
425 sampler.sampleInterlaced(scanline, iter.currY());
426 iter.next();
427 }
428 return true;
429 }
430 sampler.sampleInterlaced(scanline, iter.currY());
431 iter.next();
432 }
433 } else {
434 // easy, non-interlace case
435 const int outHeight = workingBitmap->height();
436 skip_src_rows(gif, scanline, innerWidth, sampler.srcY0());
437 for (int y = 0; y < outHeight; y++) {
438 if (DGifGetLine(gif, scanline, innerWidth) == GIF_ERROR) {
439 gif_warning(*bm, "DGifGetLine");
440 memset(scanline, fillIndex, innerWidth);
441 for (; y < outHeight; y++) {
442 sampler.next(scanline);
443 }
444 return true;
445 }
446 // scanline now contains the raw data. Sample it.
447 sampler.next(scanline);
448 if (y < outHeight - 1) {
449 skip_src_rows(gif, scanline, innerWidth, sampler.srcDY() - 1);
450 }
451 }
452 // skip the rest of the rows (if any)
453 int read = (outHeight - 1) * sampler.srcDY() + sampler.srcY0() + 1;
454 SkASSERT(read <= innerHeight);
455 skip_src_rows(gif, scanline, innerWidth, innerHeight - read);
456 }
457 sanitize_indexed_bitmap(bm);
458 return true;
459 } break;
460
461 case EXTENSION_RECORD_TYPE:
462 #if GIFLIB_MAJOR < 5
463 if (DGifGetExtension(gif, &temp_save.Function,
464 &extData) == GIF_ERROR) {
465 #else
466 if (DGifGetExtension(gif, &extFunction, &extData) == GIF_ERROR) {
467 #endif
468 return error_return(*bm, "DGifGetExtension");
469 }
470
471 while (extData != NULL) {
472 /* Create an extension block with our data */
473 #if GIFLIB_MAJOR < 5
474 if (AddExtensionBlock(&temp_save, extData[0],
475 &extData[1]) == GIF_ERROR) {
476 #else
477 if (GifAddExtensionBlock(&gif->ExtensionBlockCount,
478 &gif->ExtensionBlocks,
479 extFunction,
480 extData[0],
481 &extData[1]) == GIF_ERROR) {
482 #endif
483 return error_return(*bm, "AddExtensionBlock");
484 }
485 if (DGifGetExtensionNext(gif, &extData) == GIF_ERROR) {
486 return error_return(*bm, "DGifGetExtensionNext");
487 }
488 #if GIFLIB_MAJOR < 5
489 temp_save.Function = 0;
490 #endif
491 }
492 break;
493
494 case TERMINATE_RECORD_TYPE:
495 break;
496
497 default: /* Should be trapped by DGifGetRecordType */
498 break;
499 }
500 } while (recType != TERMINATE_RECORD_TYPE);
501
502 sanitize_indexed_bitmap(bm);
503 return true;
504 }
505
506 ///////////////////////////////////////////////////////////////////////////////
507 DEFINE_DECODER_CREATOR(GIFImageDecoder);
508 ///////////////////////////////////////////////////////////////////////////////
509
510 static bool is_gif(SkStreamRewindable* stream) {
511 char buf[GIF_STAMP_LEN];
512 if (stream->read(buf, GIF_STAMP_LEN) == GIF_STAMP_LEN) {
513 if (memcmp(GIF_STAMP, buf, GIF_STAMP_LEN) == 0 ||
514 memcmp(GIF87_STAMP, buf, GIF_STAMP_LEN) == 0 ||
515 memcmp(GIF89_STAMP, buf, GIF_STAMP_LEN) == 0) {
516 return true;
517 }
518 }
519 return false;
520 }
521
522 static SkImageDecoder* sk_libgif_dfactory(SkStreamRewindable* stream) {
523 if (is_gif(stream)) {
524 return SkNEW(SkGIFImageDecoder);
525 }
526 return NULL;
527 }
528
529 static SkImageDecoder_DecodeReg gReg(sk_libgif_dfactory);
530
531 static SkImageDecoder::Format get_format_gif(SkStreamRewindable* stream) {
532 if (is_gif(stream)) {
533 return SkImageDecoder::kGIF_Format;
534 }
535 return SkImageDecoder::kUnknown_Format;
536 }
537
538 static SkImageDecoder_FormatReg gFormatReg(get_format_gif);

Mercurial Repository: The Tor Browser

Europalab SCM Repository Server

mercurial