1/* 2 * Copyright (C) 2006 Apple 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 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 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 29#include "GIFImageReader.h" 30#include <limits> 31#include <wtf/PassOwnPtr.h> 32 33namespace WebCore { 34 35GIFImageDecoder::GIFImageDecoder(ImageSource::AlphaOption alphaOption, 36 ImageSource::GammaAndColorProfileOption gammaAndColorProfileOption) 37 : ImageDecoder(alphaOption, gammaAndColorProfileOption) 38 , m_repetitionCount(cAnimationLoopOnce) 39{ 40} 41 42GIFImageDecoder::~GIFImageDecoder() 43{ 44} 45 46void GIFImageDecoder::setData(SharedBuffer* data, bool allDataReceived) 47{ 48 if (failed()) 49 return; 50 51 ImageDecoder::setData(data, allDataReceived); 52 if (m_reader) 53 m_reader->setData(data); 54} 55 56bool GIFImageDecoder::isSizeAvailable() 57{ 58 if (!ImageDecoder::isSizeAvailable()) 59 decode(0, GIFSizeQuery); 60 61 return ImageDecoder::isSizeAvailable(); 62} 63 64bool 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 76size_t GIFImageDecoder::frameCount() 77{ 78 decode(std::numeric_limits<unsigned>::max(), GIFFrameCountQuery); 79 return m_frameBufferCache.size(); 80} 81 82int GIFImageDecoder::repetitionCount() const 83{ 84 // This value can arrive at any point in the image data stream. Most GIFs 85 // in the wild declare it near the beginning of the file, so it usually is 86 // set by the time we've decoded the size, but (depending on the GIF and the 87 // packets sent back by the webserver) not always. If the reader hasn't 88 // seen a loop count yet, it will return cLoopCountNotSeen, in which case we 89 // should default to looping once (the initial value for 90 // |m_repetitionCount|). 91 // 92 // There are some additional wrinkles here. First, ImageSource::clear() 93 // may destroy the reader, making the result from the reader _less_ 94 // authoritative on future calls if the recreated reader hasn't seen the 95 // loop count. We don't need to special-case this because in this case the 96 // new reader will once again return cLoopCountNotSeen, and we won't 97 // overwrite the cached correct value. 98 // 99 // Second, a GIF might never set a loop count at all, in which case we 100 // should continue to treat it as a "loop once" animation. We don't need 101 // special code here either, because in this case we'll never change 102 // |m_repetitionCount| from its default value. 103 // 104 // Third, we use the same GIFImageReader for counting frames and we might 105 // see the loop count and then encounter a decoding error which happens 106 // later in the stream. It is also possible that no frames are in the 107 // stream. In these cases we should just loop once. 108 if (failed() || (m_reader && (!m_reader->imagesCount()))) 109 m_repetitionCount = cAnimationLoopOnce; 110 else if (m_reader && m_reader->loopCount() != cLoopCountNotSeen) 111 m_repetitionCount = m_reader->loopCount(); 112 return m_repetitionCount; 113} 114 115ImageFrame* GIFImageDecoder::frameBufferAtIndex(size_t index) 116{ 117 if (index >= frameCount()) 118 return 0; 119 120 ImageFrame& frame = m_frameBufferCache[index]; 121 if (frame.status() != ImageFrame::FrameComplete) 122 decode(index + 1, GIFFullQuery); 123 return &frame; 124} 125 126bool GIFImageDecoder::setFailed() 127{ 128 m_reader.clear(); 129 return ImageDecoder::setFailed(); 130} 131 132void GIFImageDecoder::clearFrameBufferCache(size_t clearBeforeFrame) 133{ 134 // In some cases, like if the decoder was destroyed while animating, we 135 // can be asked to clear more frames than we currently have. 136 if (m_frameBufferCache.isEmpty()) 137 return; // Nothing to do. 138 139 // The "-1" here is tricky. It does not mean that |clearBeforeFrame| is the 140 // last frame we wish to preserve, but rather that we never want to clear 141 // the very last frame in the cache: it's empty (so clearing it is 142 // pointless), it's partial (so we don't want to clear it anyway), or the 143 // cache could be enlarged with a future setData() call and it could be 144 // needed to construct the next frame (see comments below). Callers can 145 // always use ImageSource::clear(true, ...) to completely free the memory in 146 // this case. 147 clearBeforeFrame = std::min(clearBeforeFrame, m_frameBufferCache.size() - 1); 148 const Vector<ImageFrame>::iterator end(m_frameBufferCache.begin() + clearBeforeFrame); 149 150 // We need to preserve frames such that: 151 // * We don't clear |end| 152 // * We don't clear the frame we're currently decoding 153 // * We don't clear any frame from which a future initFrameBuffer() call 154 // will copy bitmap data 155 // All other frames can be cleared. Because of the constraints on when 156 // ImageSource::clear() can be called (see ImageSource.h), we're guaranteed 157 // not to have non-empty frames after the frame we're currently decoding. 158 // So, scan backwards from |end| as follows: 159 // * If the frame is empty, we're still past any frames we care about. 160 // * If the frame is complete, but is DisposeOverwritePrevious, we'll 161 // skip over it in future initFrameBuffer() calls. We can clear it 162 // unless it's |end|, and keep scanning. For any other disposal method, 163 // stop scanning, as we've found the frame initFrameBuffer() will need 164 // next. 165 // * If the frame is partial, we're decoding it, so don't clear it; if it 166 // has a disposal method other than DisposeOverwritePrevious, stop 167 // scanning, as we'll only need this frame when decoding the next one. 168 Vector<ImageFrame>::iterator i(end); 169 for (; (i != m_frameBufferCache.begin()) && ((i->status() == ImageFrame::FrameEmpty) || (i->disposalMethod() == ImageFrame::DisposeOverwritePrevious)); --i) { 170 if ((i->status() == ImageFrame::FrameComplete) && (i != end)) 171 i->clearPixelData(); 172 } 173 174 // Now |i| holds the last frame we need to preserve; clear prior frames. 175 for (Vector<ImageFrame>::iterator j(m_frameBufferCache.begin()); j != i; ++j) { 176 ASSERT(j->status() != ImageFrame::FramePartial); 177 if (j->status() != ImageFrame::FrameEmpty) 178 j->clearPixelData(); 179 } 180} 181 182bool GIFImageDecoder::haveDecodedRow(unsigned frameIndex, const Vector<unsigned char>& rowBuffer, size_t width, size_t rowNumber, unsigned repeatCount, bool writeTransparentPixels) 183{ 184 const GIFFrameContext* frameContext = m_reader->frameContext(); 185 // The pixel data and coordinates supplied to us are relative to the frame's 186 // origin within the entire image size, i.e. 187 // (frameContext->xOffset, frameContext->yOffset). There is no guarantee 188 // that width == (size().width() - frameContext->xOffset), so 189 // we must ensure we don't run off the end of either the source data or the 190 // row's X-coordinates. 191 int xBegin = upperBoundScaledX(frameContext->xOffset); 192 int yBegin = upperBoundScaledY(frameContext->yOffset + rowNumber); 193 int xEnd = lowerBoundScaledX(std::min(static_cast<int>(frameContext->xOffset + width), size().width()) - 1, xBegin + 1) + 1; 194 int yEnd = lowerBoundScaledY(std::min(static_cast<int>(frameContext->yOffset + rowNumber + repeatCount), size().height()) - 1, yBegin + 1) + 1; 195 if (rowBuffer.isEmpty() || (xBegin < 0) || (yBegin < 0) || (xEnd <= xBegin) || (yEnd <= yBegin)) 196 return true; 197 198 // Get the colormap. 199 const unsigned char* colorMap; 200 unsigned colorMapSize; 201 if (frameContext->isLocalColormapDefined) { 202 colorMap = m_reader->localColormap(frameContext); 203 colorMapSize = m_reader->localColormapSize(frameContext); 204 } else { 205 colorMap = m_reader->globalColormap(); 206 colorMapSize = m_reader->globalColormapSize(); 207 } 208 if (!colorMap) 209 return true; 210 211 // Initialize the frame if necessary. 212 ImageFrame& buffer = m_frameBufferCache[frameIndex]; 213 if (((buffer.status() == ImageFrame::FrameEmpty) && !initFrameBuffer(frameIndex)) || !buffer.hasPixelData()) 214 return false; 215 216 ImageFrame::PixelData* currentAddress = buffer.getAddr(xBegin, yBegin); 217 // Write one row's worth of data into the frame. 218 for (int x = xBegin; x < xEnd; ++x) { 219 const unsigned char sourceValue = rowBuffer[(m_scaled ? m_scaledColumns[x] : x) - frameContext->xOffset]; 220 if ((!frameContext->isTransparent || (sourceValue != frameContext->tpixel)) && (sourceValue < colorMapSize)) { 221 const size_t colorIndex = static_cast<size_t>(sourceValue) * 3; 222 buffer.setRGBA(currentAddress, colorMap[colorIndex], colorMap[colorIndex + 1], colorMap[colorIndex + 2], 255); 223 } else { 224 m_currentBufferSawAlpha = true; 225 // We may or may not need to write transparent pixels to the buffer. 226 // If we're compositing against a previous image, it's wrong, and if 227 // we're writing atop a cleared, fully transparent buffer, it's 228 // unnecessary; but if we're decoding an interlaced gif and 229 // displaying it "Haeberli"-style, we must write these for passes 230 // beyond the first, or the initial passes will "show through" the 231 // later ones. 232 if (writeTransparentPixels) 233 buffer.setRGBA(currentAddress, 0, 0, 0, 0); 234 } 235 ++currentAddress; 236 } 237 238 // Tell the frame to copy the row data if need be. 239 if (repeatCount > 1) 240 buffer.copyRowNTimes(xBegin, xEnd, yBegin, yEnd); 241 242 return true; 243} 244 245bool GIFImageDecoder::frameComplete(unsigned frameIndex, unsigned frameDuration, ImageFrame::FrameDisposalMethod disposalMethod) 246{ 247 // Initialize the frame if necessary. Some GIFs insert do-nothing frames, 248 // in which case we never reach haveDecodedRow() before getting here. 249 ImageFrame& buffer = m_frameBufferCache[frameIndex]; 250 if ((buffer.status() == ImageFrame::FrameEmpty) && !initFrameBuffer(frameIndex)) 251 return false; // initFrameBuffer() has already called setFailed(). 252 253 buffer.setStatus(ImageFrame::FrameComplete); 254 buffer.setDuration(frameDuration); 255 buffer.setDisposalMethod(disposalMethod); 256 257 if (!m_currentBufferSawAlpha) { 258 // The whole frame was non-transparent, so it's possible that the entire 259 // resulting buffer was non-transparent, and we can setHasAlpha(false). 260 if (buffer.originalFrameRect().contains(IntRect(IntPoint(), scaledSize()))) 261 buffer.setHasAlpha(false); 262 else if (frameIndex) { 263 // Tricky case. This frame does not have alpha only if everywhere 264 // outside its rect doesn't have alpha. To know whether this is 265 // true, we check the start state of the frame -- if it doesn't have 266 // alpha, we're safe. 267 // 268 // First skip over prior DisposeOverwritePrevious frames (since they 269 // don't affect the start state of this frame) the same way we do in 270 // initFrameBuffer(). 271 const ImageFrame* prevBuffer = &m_frameBufferCache[--frameIndex]; 272 while (frameIndex && (prevBuffer->disposalMethod() == ImageFrame::DisposeOverwritePrevious)) 273 prevBuffer = &m_frameBufferCache[--frameIndex]; 274 275 // Now, if we're at a DisposeNotSpecified or DisposeKeep frame, then 276 // we can say we have no alpha if that frame had no alpha. But 277 // since in initFrameBuffer() we already copied that frame's alpha 278 // state into the current frame's, we need do nothing at all here. 279 // 280 // The only remaining case is a DisposeOverwriteBgcolor frame. If 281 // it had no alpha, and its rect is contained in the current frame's 282 // rect, we know the current frame has no alpha. 283 if ((prevBuffer->disposalMethod() == ImageFrame::DisposeOverwriteBgcolor) && !prevBuffer->hasAlpha() && buffer.originalFrameRect().contains(prevBuffer->originalFrameRect())) 284 buffer.setHasAlpha(false); 285 } 286 } 287 288 return true; 289} 290 291void GIFImageDecoder::gifComplete() 292{ 293 // Cache the repetition count, which is now as authoritative as it's ever 294 // going to be. 295 repetitionCount(); 296 297 m_reader.clear(); 298} 299 300void GIFImageDecoder::decode(unsigned haltAtFrame, GIFQuery query) 301{ 302 if (failed()) 303 return; 304 305 if (!m_reader) { 306 m_reader = adoptPtr(new GIFImageReader(this)); 307 m_reader->setData(m_data); 308 } 309 310 if (query == GIFSizeQuery) { 311 if (!m_reader->decode(GIFSizeQuery, haltAtFrame)) 312 setFailed(); 313 return; 314 } 315 316 if (!m_reader->decode(GIFFrameCountQuery, haltAtFrame)) { 317 setFailed(); 318 return; 319 } 320 321 const size_t oldSize = m_frameBufferCache.size(); 322 m_frameBufferCache.resize(m_reader->imagesCount()); 323 for (size_t i = oldSize; i < m_reader->imagesCount(); ++i) 324 m_frameBufferCache[i].setPremultiplyAlpha(m_premultiplyAlpha); 325 326 if (query == GIFFrameCountQuery) 327 return; 328 329 if (!m_reader->decode(GIFFullQuery, haltAtFrame)) { 330 setFailed(); 331 return; 332 } 333 334 // It is also a fatal error if all data is received but we failed to decode 335 // all frames completely. 336 if (isAllDataReceived() && haltAtFrame >= m_frameBufferCache.size() && m_reader) 337 setFailed(); 338} 339 340bool GIFImageDecoder::initFrameBuffer(unsigned frameIndex) 341{ 342 // Initialize the frame rect in our buffer. 343 const GIFFrameContext* frameContext = m_reader->frameContext(); 344 IntRect frameRect(frameContext->xOffset, frameContext->yOffset, frameContext->width, frameContext->height); 345 346 // Make sure the frameRect doesn't extend outside the buffer. 347 if (frameRect.maxX() > size().width()) 348 frameRect.setWidth(size().width() - frameContext->xOffset); 349 if (frameRect.maxY() > size().height()) 350 frameRect.setHeight(size().height() - frameContext->yOffset); 351 352 ImageFrame* const buffer = &m_frameBufferCache[frameIndex]; 353 int left = upperBoundScaledX(frameRect.x()); 354 int right = lowerBoundScaledX(frameRect.maxX(), left); 355 int top = upperBoundScaledY(frameRect.y()); 356 int bottom = lowerBoundScaledY(frameRect.maxY(), top); 357 buffer->setOriginalFrameRect(IntRect(left, top, right - left, bottom - top)); 358 359 if (!frameIndex) { 360 // This is the first frame, so we're not relying on any previous data. 361 if (!buffer->setSize(scaledSize().width(), scaledSize().height())) 362 return setFailed(); 363 } else { 364 // The starting state for this frame depends on the previous frame's 365 // disposal method. 366 // 367 // Frames that use the DisposeOverwritePrevious method are effectively 368 // no-ops in terms of changing the starting state of a frame compared to 369 // the starting state of the previous frame, so skip over them. (If the 370 // first frame specifies this method, it will get treated like 371 // DisposeOverwriteBgcolor below and reset to a completely empty image.) 372 const ImageFrame* prevBuffer = &m_frameBufferCache[--frameIndex]; 373 ImageFrame::FrameDisposalMethod prevMethod = prevBuffer->disposalMethod(); 374 while (frameIndex && (prevMethod == ImageFrame::DisposeOverwritePrevious)) { 375 prevBuffer = &m_frameBufferCache[--frameIndex]; 376 prevMethod = prevBuffer->disposalMethod(); 377 } 378 ASSERT(prevBuffer->status() == ImageFrame::FrameComplete); 379 380 if ((prevMethod == ImageFrame::DisposeNotSpecified) || (prevMethod == ImageFrame::DisposeKeep)) { 381 // Preserve the last frame as the starting state for this frame. 382 if (!buffer->copyBitmapData(*prevBuffer)) 383 return setFailed(); 384 } else { 385 // We want to clear the previous frame to transparent, without 386 // affecting pixels in the image outside of the frame. 387 const IntRect& prevRect = prevBuffer->originalFrameRect(); 388 const IntSize& bufferSize = scaledSize(); 389 if (!frameIndex || prevRect.contains(IntRect(IntPoint(), scaledSize()))) { 390 // Clearing the first frame, or a frame the size of the whole 391 // image, results in a completely empty image. 392 if (!buffer->setSize(bufferSize.width(), bufferSize.height())) 393 return setFailed(); 394 } else { 395 // Copy the whole previous buffer, then clear just its frame. 396 if (!buffer->copyBitmapData(*prevBuffer)) 397 return setFailed(); 398 buffer->zeroFillFrameRect(prevRect); 399 } 400 } 401 } 402 403 // Update our status to be partially complete. 404 buffer->setStatus(ImageFrame::FramePartial); 405 406 // Reset the alpha pixel tracker for this frame. 407 m_currentBufferSawAlpha = false; 408 return true; 409} 410 411} // namespace WebCore 412