1 /* 2 * Copyright (C) 2006 Apple Computer, Inc. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY 14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE COMPUTER, INC. OR 17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY 21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24 */ 25 26 #include "config.h" 27 #include "GIFImageDecoder.h" 28 #include "GIFImageReader.h" 29 30 namespace WebCore { 31 32 GIFImageDecoder::GIFImageDecoder(ImageSource::AlphaOption alphaOption, 33 ImageSource::GammaAndColorProfileOption gammaAndColorProfileOption) 34 : ImageDecoder(alphaOption, gammaAndColorProfileOption) 35 , m_alreadyScannedThisDataForFrameCount(true) 36 , m_repetitionCount(cAnimationLoopOnce) 37 , m_readOffset(0) 38 { 39 } 40 41 GIFImageDecoder::~GIFImageDecoder() 42 { 43 } 44 45 void GIFImageDecoder::setData(SharedBuffer* data, bool allDataReceived) 46 { 47 if (failed()) 48 return; 49 50 ImageDecoder::setData(data, allDataReceived); 51 52 // We need to rescan the frame count, as the new data may have changed it. 53 m_alreadyScannedThisDataForFrameCount = false; 54 } 55 56 bool GIFImageDecoder::isSizeAvailable() 57 { 58 if (!ImageDecoder::isSizeAvailable()) 59 decode(0, GIFSizeQuery); 60 61 return ImageDecoder::isSizeAvailable(); 62 } 63 64 bool GIFImageDecoder::setSize(unsigned width, unsigned height) 65 { 66 if (ImageDecoder::isSizeAvailable() && size() == IntSize(width, height)) 67 return true; 68 69 if (!ImageDecoder::setSize(width, height)) 70 return false; 71 72 prepareScaleDataIfNecessary(); 73 return true; 74 } 75 76 size_t GIFImageDecoder::frameCount() 77 { 78 if (!m_alreadyScannedThisDataForFrameCount) { 79 // FIXME: Scanning all the data has O(n^2) behavior if the data were to 80 // come in really slowly. Might be interesting to try to clone our 81 // existing read session to preserve state, but for now we just crawl 82 // all the data. Note that this is no worse than what ImageIO does on 83 // Mac right now (it also crawls all the data again). 84 GIFImageReader reader(0); 85 reader.read((const unsigned char*)m_data->data(), m_data->size(), GIFFrameCountQuery, static_cast<unsigned>(-1)); 86 m_alreadyScannedThisDataForFrameCount = true; 87 m_frameBufferCache.resize(reader.images_count); 88 for (int i = 0; i < reader.images_count; ++i) 89 m_frameBufferCache[i].setPremultiplyAlpha(m_premultiplyAlpha); 90 } 91 92 return m_frameBufferCache.size(); 93 } 94 95 int GIFImageDecoder::repetitionCount() const 96 { 97 // This value can arrive at any point in the image data stream. Most GIFs 98 // in the wild declare it near the beginning of the file, so it usually is 99 // set by the time we've decoded the size, but (depending on the GIF and the 100 // packets sent back by the webserver) not always. If the reader hasn't 101 // seen a loop count yet, it will return cLoopCountNotSeen, in which case we 102 // should default to looping once (the initial value for 103 // |m_repetitionCount|). 104 // 105 // There are two additional wrinkles here. First, ImageSource::clear() may 106 // destroy the reader, making the result from the reader _less_ 107 // authoritative on future calls if the recreated reader hasn't seen the 108 // loop count. We don't need to special-case this because in this case the 109 // new reader will once again return cLoopCountNotSeen, and we won't 110 // overwrite the cached correct value. 111 // 112 // Second, a GIF might never set a loop count at all, in which case we 113 // should continue to treat it as a "loop once" animation. We don't need 114 // special code here either, because in this case we'll never change 115 // |m_repetitionCount| from its default value. 116 if (m_reader && (m_reader->loop_count != cLoopCountNotSeen)) 117 m_repetitionCount = m_reader->loop_count; 118 return m_repetitionCount; 119 } 120 121 ImageFrame* GIFImageDecoder::frameBufferAtIndex(size_t index) 122 { 123 if (index >= frameCount()) 124 return 0; 125 126 ImageFrame& frame = m_frameBufferCache[index]; 127 if (frame.status() != ImageFrame::FrameComplete) 128 decode(index + 1, GIFFullQuery); 129 return &frame; 130 } 131 132 bool GIFImageDecoder::setFailed() 133 { 134 m_reader.clear(); 135 return ImageDecoder::setFailed(); 136 } 137 138 void GIFImageDecoder::clearFrameBufferCache(size_t clearBeforeFrame) 139 { 140 // In some cases, like if the decoder was destroyed while animating, we 141 // can be asked to clear more frames than we currently have. 142 if (m_frameBufferCache.isEmpty()) 143 return; // Nothing to do. 144 145 // The "-1" here is tricky. It does not mean that |clearBeforeFrame| is the 146 // last frame we wish to preserve, but rather that we never want to clear 147 // the very last frame in the cache: it's empty (so clearing it is 148 // pointless), it's partial (so we don't want to clear it anyway), or the 149 // cache could be enlarged with a future setData() call and it could be 150 // needed to construct the next frame (see comments below). Callers can 151 // always use ImageSource::clear(true, ...) to completely free the memory in 152 // this case. 153 clearBeforeFrame = std::min(clearBeforeFrame, m_frameBufferCache.size() - 1); 154 const Vector<ImageFrame>::iterator end(m_frameBufferCache.begin() + clearBeforeFrame); 155 156 // We need to preserve frames such that: 157 // * We don't clear |end| 158 // * We don't clear the frame we're currently decoding 159 // * We don't clear any frame from which a future initFrameBuffer() call 160 // will copy bitmap data 161 // All other frames can be cleared. Because of the constraints on when 162 // ImageSource::clear() can be called (see ImageSource.h), we're guaranteed 163 // not to have non-empty frames after the frame we're currently decoding. 164 // So, scan backwards from |end| as follows: 165 // * If the frame is empty, we're still past any frames we care about. 166 // * If the frame is complete, but is DisposeOverwritePrevious, we'll 167 // skip over it in future initFrameBuffer() calls. We can clear it 168 // unless it's |end|, and keep scanning. For any other disposal method, 169 // stop scanning, as we've found the frame initFrameBuffer() will need 170 // next. 171 // * If the frame is partial, we're decoding it, so don't clear it; if it 172 // has a disposal method other than DisposeOverwritePrevious, stop 173 // scanning, as we'll only need this frame when decoding the next one. 174 Vector<ImageFrame>::iterator i(end); 175 for (; (i != m_frameBufferCache.begin()) && ((i->status() == ImageFrame::FrameEmpty) || (i->disposalMethod() == ImageFrame::DisposeOverwritePrevious)); --i) { 176 if ((i->status() == ImageFrame::FrameComplete) && (i != end)) 177 i->clearPixelData(); 178 } 179 180 // Now |i| holds the last frame we need to preserve; clear prior frames. 181 for (Vector<ImageFrame>::iterator j(m_frameBufferCache.begin()); j != i; ++j) { 182 ASSERT(j->status() != ImageFrame::FramePartial); 183 if (j->status() != ImageFrame::FrameEmpty) 184 j->clearPixelData(); 185 } 186 } 187 188 void GIFImageDecoder::decodingHalted(unsigned bytesLeft) 189 { 190 m_readOffset = m_data->size() - bytesLeft; 191 } 192 193 bool GIFImageDecoder::haveDecodedRow(unsigned frameIndex, unsigned char* rowBuffer, unsigned char* rowEnd, unsigned rowNumber, unsigned repeatCount, bool writeTransparentPixels) 194 { 195 const GIFFrameReader* frameReader = m_reader->frame_reader; 196 // The pixel data and coordinates supplied to us are relative to the frame's 197 // origin within the entire image size, i.e. 198 // (frameReader->x_offset, frameReader->y_offset). There is no guarantee 199 // that (rowEnd - rowBuffer) == (size().width() - frameReader->x_offset), so 200 // we must ensure we don't run off the end of either the source data or the 201 // row's X-coordinates. 202 int xBegin = upperBoundScaledX(frameReader->x_offset); 203 int yBegin = upperBoundScaledY(frameReader->y_offset + rowNumber); 204 int xEnd = lowerBoundScaledX(std::min(static_cast<int>(frameReader->x_offset + (rowEnd - rowBuffer)), size().width()) - 1, xBegin + 1) + 1; 205 int yEnd = lowerBoundScaledY(std::min(static_cast<int>(frameReader->y_offset + rowNumber + repeatCount), size().height()) - 1, yBegin + 1) + 1; 206 if (!rowBuffer || (xBegin < 0) || (yBegin < 0) || (xEnd <= xBegin) || (yEnd <= yBegin)) 207 return true; 208 209 // Get the colormap. 210 const unsigned char* colorMap; 211 unsigned colorMapSize; 212 if (frameReader->is_local_colormap_defined) { 213 colorMap = frameReader->local_colormap; 214 colorMapSize = (unsigned)frameReader->local_colormap_size; 215 } else { 216 colorMap = m_reader->global_colormap; 217 colorMapSize = m_reader->global_colormap_size; 218 } 219 if (!colorMap) 220 return true; 221 222 // Initialize the frame if necessary. 223 ImageFrame& buffer = m_frameBufferCache[frameIndex]; 224 if ((buffer.status() == ImageFrame::FrameEmpty) && !initFrameBuffer(frameIndex)) 225 return false; 226 227 // Write one row's worth of data into the frame. 228 for (int x = xBegin; x < xEnd; ++x) { 229 const unsigned char sourceValue = *(rowBuffer + (m_scaled ? m_scaledColumns[x] : x) - frameReader->x_offset); 230 if ((!frameReader->is_transparent || (sourceValue != frameReader->tpixel)) && (sourceValue < colorMapSize)) { 231 const size_t colorIndex = static_cast<size_t>(sourceValue) * 3; 232 buffer.setRGBA(x, yBegin, colorMap[colorIndex], colorMap[colorIndex + 1], colorMap[colorIndex + 2], 255); 233 } else { 234 m_currentBufferSawAlpha = true; 235 // We may or may not need to write transparent pixels to the buffer. 236 // If we're compositing against a previous image, it's wrong, and if 237 // we're writing atop a cleared, fully transparent buffer, it's 238 // unnecessary; but if we're decoding an interlaced gif and 239 // displaying it "Haeberli"-style, we must write these for passes 240 // beyond the first, or the initial passes will "show through" the 241 // later ones. 242 if (writeTransparentPixels) 243 buffer.setRGBA(x, yBegin, 0, 0, 0, 0); 244 } 245 } 246 247 // Tell the frame to copy the row data if need be. 248 if (repeatCount > 1) 249 buffer.copyRowNTimes(xBegin, xEnd, yBegin, yEnd); 250 251 return true; 252 } 253 254 bool GIFImageDecoder::frameComplete(unsigned frameIndex, unsigned frameDuration, ImageFrame::FrameDisposalMethod disposalMethod) 255 { 256 // Initialize the frame if necessary. Some GIFs insert do-nothing frames, 257 // in which case we never reach haveDecodedRow() before getting here. 258 ImageFrame& buffer = m_frameBufferCache[frameIndex]; 259 if ((buffer.status() == ImageFrame::FrameEmpty) && !initFrameBuffer(frameIndex)) 260 return false; // initFrameBuffer() has already called setFailed(). 261 262 buffer.setStatus(ImageFrame::FrameComplete); 263 buffer.setDuration(frameDuration); 264 buffer.setDisposalMethod(disposalMethod); 265 266 if (!m_currentBufferSawAlpha) { 267 // The whole frame was non-transparent, so it's possible that the entire 268 // resulting buffer was non-transparent, and we can setHasAlpha(false). 269 if (buffer.originalFrameRect().contains(IntRect(IntPoint(), scaledSize()))) 270 buffer.setHasAlpha(false); 271 else if (frameIndex) { 272 // Tricky case. This frame does not have alpha only if everywhere 273 // outside its rect doesn't have alpha. To know whether this is 274 // true, we check the start state of the frame -- if it doesn't have 275 // alpha, we're safe. 276 // 277 // First skip over prior DisposeOverwritePrevious frames (since they 278 // don't affect the start state of this frame) the same way we do in 279 // initFrameBuffer(). 280 const ImageFrame* prevBuffer = &m_frameBufferCache[--frameIndex]; 281 while (frameIndex && (prevBuffer->disposalMethod() == ImageFrame::DisposeOverwritePrevious)) 282 prevBuffer = &m_frameBufferCache[--frameIndex]; 283 284 // Now, if we're at a DisposeNotSpecified or DisposeKeep frame, then 285 // we can say we have no alpha if that frame had no alpha. But 286 // since in initFrameBuffer() we already copied that frame's alpha 287 // state into the current frame's, we need do nothing at all here. 288 // 289 // The only remaining case is a DisposeOverwriteBgcolor frame. If 290 // it had no alpha, and its rect is contained in the current frame's 291 // rect, we know the current frame has no alpha. 292 if ((prevBuffer->disposalMethod() == ImageFrame::DisposeOverwriteBgcolor) && !prevBuffer->hasAlpha() && buffer.originalFrameRect().contains(prevBuffer->originalFrameRect())) 293 buffer.setHasAlpha(false); 294 } 295 } 296 297 return true; 298 } 299 300 void GIFImageDecoder::gifComplete() 301 { 302 // Cache the repetition count, which is now as authoritative as it's ever 303 // going to be. 304 repetitionCount(); 305 306 m_reader.clear(); 307 } 308 309 void GIFImageDecoder::decode(unsigned haltAtFrame, GIFQuery query) 310 { 311 if (failed()) 312 return; 313 314 if (!m_reader) 315 m_reader.set(new GIFImageReader(this)); 316 317 // If we couldn't decode the image but we've received all the data, decoding 318 // has failed. 319 if (!m_reader->read((const unsigned char*)m_data->data() + m_readOffset, m_data->size() - m_readOffset, query, haltAtFrame) && isAllDataReceived()) 320 setFailed(); 321 } 322 323 bool GIFImageDecoder::initFrameBuffer(unsigned frameIndex) 324 { 325 // Initialize the frame rect in our buffer. 326 const GIFFrameReader* frameReader = m_reader->frame_reader; 327 IntRect frameRect(frameReader->x_offset, frameReader->y_offset, frameReader->width, frameReader->height); 328 329 // Make sure the frameRect doesn't extend outside the buffer. 330 if (frameRect.maxX() > size().width()) 331 frameRect.setWidth(size().width() - frameReader->x_offset); 332 if (frameRect.maxY() > size().height()) 333 frameRect.setHeight(size().height() - frameReader->y_offset); 334 335 ImageFrame* const buffer = &m_frameBufferCache[frameIndex]; 336 int left = upperBoundScaledX(frameRect.x()); 337 int right = lowerBoundScaledX(frameRect.maxX(), left); 338 int top = upperBoundScaledY(frameRect.y()); 339 int bottom = lowerBoundScaledY(frameRect.maxY(), top); 340 buffer->setOriginalFrameRect(IntRect(left, top, right - left, bottom - top)); 341 342 if (!frameIndex) { 343 // This is the first frame, so we're not relying on any previous data. 344 if (!buffer->setSize(scaledSize().width(), scaledSize().height())) 345 return setFailed(); 346 } else { 347 // The starting state for this frame depends on the previous frame's 348 // disposal method. 349 // 350 // Frames that use the DisposeOverwritePrevious method are effectively 351 // no-ops in terms of changing the starting state of a frame compared to 352 // the starting state of the previous frame, so skip over them. (If the 353 // first frame specifies this method, it will get treated like 354 // DisposeOverwriteBgcolor below and reset to a completely empty image.) 355 const ImageFrame* prevBuffer = &m_frameBufferCache[--frameIndex]; 356 ImageFrame::FrameDisposalMethod prevMethod = prevBuffer->disposalMethod(); 357 while (frameIndex && (prevMethod == ImageFrame::DisposeOverwritePrevious)) { 358 prevBuffer = &m_frameBufferCache[--frameIndex]; 359 prevMethod = prevBuffer->disposalMethod(); 360 } 361 ASSERT(prevBuffer->status() == ImageFrame::FrameComplete); 362 363 if ((prevMethod == ImageFrame::DisposeNotSpecified) || (prevMethod == ImageFrame::DisposeKeep)) { 364 // Preserve the last frame as the starting state for this frame. 365 if (!buffer->copyBitmapData(*prevBuffer)) 366 return setFailed(); 367 } else { 368 // We want to clear the previous frame to transparent, without 369 // affecting pixels in the image outside of the frame. 370 const IntRect& prevRect = prevBuffer->originalFrameRect(); 371 const IntSize& bufferSize = scaledSize(); 372 if (!frameIndex || prevRect.contains(IntRect(IntPoint(), scaledSize()))) { 373 // Clearing the first frame, or a frame the size of the whole 374 // image, results in a completely empty image. 375 if (!buffer->setSize(bufferSize.width(), bufferSize.height())) 376 return setFailed(); 377 } else { 378 // Copy the whole previous buffer, then clear just its frame. 379 if (!buffer->copyBitmapData(*prevBuffer)) 380 return setFailed(); 381 for (int y = prevRect.y(); y < prevRect.maxY(); ++y) { 382 for (int x = prevRect.x(); x < prevRect.maxX(); ++x) 383 buffer->setRGBA(x, y, 0, 0, 0, 0); 384 } 385 if ((prevRect.width() > 0) && (prevRect.height() > 0)) 386 buffer->setHasAlpha(true); 387 } 388 } 389 } 390 391 // Update our status to be partially complete. 392 buffer->setStatus(ImageFrame::FramePartial); 393 394 // Reset the alpha pixel tracker for this frame. 395 m_currentBufferSawAlpha = false; 396 return true; 397 } 398 399 } // namespace WebCore 400
