| /* |
| * Copyright (C) 2006 Apple Inc. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY |
| * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR |
| * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
| * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY |
| * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #include "config.h" |
| #include "GIFImageDecoder.h" |
| |
| #include "GIFImageReader.h" |
| #include <limits> |
| |
| namespace WebCore { |
| |
| GIFImageDecoder::GIFImageDecoder(AlphaOption alphaOption, GammaAndColorProfileOption gammaAndColorProfileOption) |
| : ScalableImageDecoder(alphaOption, gammaAndColorProfileOption) |
| { |
| } |
| |
| GIFImageDecoder::~GIFImageDecoder() = default; |
| |
| void GIFImageDecoder::setData(SharedBuffer& data, bool allDataReceived) |
| { |
| if (failed()) |
| return; |
| |
| ScalableImageDecoder::setData(data, allDataReceived); |
| if (m_reader) |
| m_reader->setData(*m_data); |
| } |
| |
| bool GIFImageDecoder::setSize(const IntSize& size) |
| { |
| if (ScalableImageDecoder::encodedDataStatus() >= EncodedDataStatus::SizeAvailable && this->size() == size) |
| return true; |
| |
| return ScalableImageDecoder::setSize(size); |
| } |
| |
| size_t GIFImageDecoder::frameCount() const |
| { |
| const_cast<GIFImageDecoder*>(this)->decode(std::numeric_limits<unsigned>::max(), GIFFrameCountQuery, isAllDataReceived()); |
| return m_frameBufferCache.size(); |
| } |
| |
| RepetitionCount GIFImageDecoder::repetitionCount() const |
| { |
| // This value can arrive at any point in the image data stream. Most GIFs |
| // in the wild declare it near the beginning of the file, so it usually is |
| // set by the time we've decoded the size, but (depending on the GIF and the |
| // packets sent back by the webserver) not always. If the reader hasn't |
| // seen a loop count yet, it will return cLoopCountNotSeen, in which case we |
| // should default to looping once (the initial value for |
| // |m_repetitionCount|). |
| // |
| // There are some additional wrinkles here. First, ImageSource::clear() |
| // may destroy the reader, making the result from the reader _less_ |
| // authoritative on future calls if the recreated reader hasn't seen the |
| // loop count. We don't need to special-case this because in this case the |
| // new reader will once again return cLoopCountNotSeen, and we won't |
| // overwrite the cached correct value. |
| // |
| // Second, a GIF might never set a loop count at all, in which case we |
| // should continue to treat it as a "loop once" animation. We don't need |
| // special code here either, because in this case we'll never change |
| // |m_repetitionCount| from its default value. |
| // |
| // Third, we use the same GIFImageReader for counting frames and we might |
| // see the loop count and then encounter a decoding error which happens |
| // later in the stream. It is also possible that no frames are in the |
| // stream. In these cases we should just loop once. |
| if (failed() || (m_reader && (!m_reader->imagesCount()))) |
| m_repetitionCount = RepetitionCountOnce; |
| else if (m_reader && m_reader->loopCount() != cLoopCountNotSeen) |
| m_repetitionCount = m_reader->loopCount() > 0 ? m_reader->loopCount() + 1 : m_reader->loopCount(); |
| return m_repetitionCount; |
| } |
| |
| size_t GIFImageDecoder::findFirstRequiredFrameToDecode(size_t frameIndex) |
| { |
| // The first frame doesn't depend on any other. |
| if (!frameIndex) |
| return 0; |
| |
| for (size_t i = frameIndex; i > 0; --i) { |
| auto& frame = m_frameBufferCache[i - 1]; |
| |
| // Frames with disposal method RestoreToPrevious are useless, skip them. |
| if (frame.disposalMethod() == ScalableImageDecoderFrame::DisposalMethod::RestoreToPrevious) |
| continue; |
| |
| // At this point the disposal method can be Unspecified, DoNotDispose or RestoreToBackground. |
| // In every case, if the frame is complete we can start decoding the next one. |
| if (frame.isComplete()) |
| return i; |
| |
| // If the disposal method of this frame is RestoreToBackground and it fills the whole area, |
| // the next frame's backing store is initialized to transparent, so we start decoding with it. |
| if (frame.disposalMethod() == ScalableImageDecoderFrame::DisposalMethod::RestoreToBackground) { |
| // We cannot use frame.backingStore()->frameRect() here, because it has been cleared |
| // when the frame was removed from the cache. We need to get the values from the |
| // reader context. |
| const auto* frameContext = m_reader->frameContext(i - 1); |
| ASSERT(frameContext); |
| IntRect frameRect(frameContext->xOffset, frameContext->yOffset, frameContext->width, frameContext->height); |
| if (frameRect.contains({ { }, size() })) |
| return i; |
| } |
| } |
| |
| return 0; |
| } |
| |
| ScalableImageDecoderFrame* GIFImageDecoder::frameBufferAtIndex(size_t index) |
| { |
| if (index >= frameCount()) |
| return 0; |
| |
| auto& frame = m_frameBufferCache[index]; |
| if (!frame.isComplete()) { |
| for (auto i = findFirstRequiredFrameToDecode(index); i <= index; i++) |
| decode(i + 1, GIFFullQuery, isAllDataReceived()); |
| } |
| |
| return &frame; |
| } |
| |
| bool GIFImageDecoder::setFailed() |
| { |
| m_reader = nullptr; |
| return ScalableImageDecoder::setFailed(); |
| } |
| |
| void GIFImageDecoder::clearFrameBufferCache(size_t clearBeforeFrame) |
| { |
| // In some cases, like if the decoder was destroyed while animating, we |
| // can be asked to clear more frames than we currently have. |
| if (m_frameBufferCache.isEmpty()) |
| return; // Nothing to do. |
| |
| // The "-1" here is tricky. It does not mean that |clearBeforeFrame| is the |
| // last frame we wish to preserve, but rather that we never want to clear |
| // the very last frame in the cache: it's empty (so clearing it is |
| // pointless), it's partial (so we don't want to clear it anyway), or the |
| // cache could be enlarged with a future setData() call and it could be |
| // needed to construct the next frame (see comments below). Callers can |
| // always use ImageSource::clear(true, ...) to completely free the memory in |
| // this case. |
| clearBeforeFrame = std::min(clearBeforeFrame, m_frameBufferCache.size() - 1); |
| const Vector<ScalableImageDecoderFrame>::iterator end(m_frameBufferCache.begin() + clearBeforeFrame); |
| |
| // We need to preserve frames such that: |
| // * We don't clear |end| |
| // * We don't clear the frame we're currently decoding |
| // * We don't clear any frame from which a future initFrameBuffer() call |
| // will copy bitmap data |
| // All other frames can be cleared. Because of the constraints on when |
| // ImageSource::clear() can be called (see ImageSource.h), we're guaranteed |
| // not to have non-empty frames after the frame we're currently decoding. |
| // So, scan backwards from |end| as follows: |
| // * If the frame is empty, we're still past any frames we care about. |
| // * If the frame is complete, but is DisposalMethod::RestoreToPrevious, we'll |
| // skip over it in future initFrameBuffer() calls. We can clear it |
| // unless it's |end|, and keep scanning. For any other disposal method, |
| // stop scanning, as we've found the frame initFrameBuffer() will need |
| // next. |
| // * If the frame is partial, we're decoding it, so don't clear it; if it |
| // has a disposal method other than DisposalMethod::RestoreToPrevious, stop |
| // scanning, as we'll only need this frame when decoding the next one. |
| Vector<ScalableImageDecoderFrame>::iterator i(end); |
| for (; (i != m_frameBufferCache.begin()) && (i->isInvalid() || (i->disposalMethod() == ScalableImageDecoderFrame::DisposalMethod::RestoreToPrevious)); --i) { |
| if (i->isComplete() && (i != end)) |
| i->clear(); |
| } |
| |
| // Now |i| holds the last frame we need to preserve; clear prior frames. |
| for (Vector<ScalableImageDecoderFrame>::iterator j(m_frameBufferCache.begin()); j != i; ++j) { |
| ASSERT(!j->isPartial()); |
| if (!j->isInvalid()) |
| j->clear(); |
| } |
| } |
| |
| bool GIFImageDecoder::haveDecodedRow(unsigned frameIndex, const Vector<unsigned char>& rowBuffer, size_t width, size_t rowNumber, unsigned repeatCount, bool writeTransparentPixels) |
| { |
| const GIFFrameContext* frameContext = m_reader->frameContext(); |
| // The pixel data and coordinates supplied to us are relative to the frame's |
| // origin within the entire image size, i.e. |
| // (frameContext->xOffset, frameContext->yOffset). There is no guarantee |
| // that width == (size().width() - frameContext->xOffset), so |
| // we must ensure we don't run off the end of either the source data or the |
| // row's X-coordinates. |
| int xBegin = frameContext->xOffset; |
| int yBegin = frameContext->yOffset + rowNumber; |
| int xEnd = std::min(static_cast<int>(frameContext->xOffset + width), size().width()); |
| int yEnd = std::min(static_cast<int>(frameContext->yOffset + rowNumber + repeatCount), size().height()); |
| if (rowBuffer.isEmpty() || xEnd <= xBegin || yEnd <= yBegin) |
| return true; |
| |
| // Get the colormap. |
| const unsigned char* colorMap; |
| unsigned colorMapSize; |
| if (frameContext->isLocalColormapDefined) { |
| colorMap = m_reader->localColormap(frameContext); |
| colorMapSize = m_reader->localColormapSize(frameContext); |
| } else { |
| colorMap = m_reader->globalColormap(); |
| colorMapSize = m_reader->globalColormapSize(); |
| } |
| if (!colorMap) |
| return true; |
| |
| // Initialize the frame if necessary. |
| auto& buffer = m_frameBufferCache[frameIndex]; |
| if ((buffer.isInvalid() && !initFrameBuffer(frameIndex)) || !buffer.hasBackingStore()) |
| return false; |
| |
| auto* currentAddress = buffer.backingStore()->pixelAt(xBegin, yBegin); |
| // Write one row's worth of data into the frame. |
| for (int x = xBegin; x < xEnd; ++x) { |
| const unsigned char sourceValue = rowBuffer[x - frameContext->xOffset]; |
| if ((!frameContext->isTransparent || (sourceValue != frameContext->tpixel)) && (sourceValue < colorMapSize)) { |
| const size_t colorIndex = static_cast<size_t>(sourceValue) * 3; |
| buffer.backingStore()->setPixel(currentAddress, colorMap[colorIndex], colorMap[colorIndex + 1], colorMap[colorIndex + 2], 255); |
| } else { |
| m_currentBufferSawAlpha = true; |
| // We may or may not need to write transparent pixels to the buffer. |
| // If we're compositing against a previous image, it's wrong, and if |
| // we're writing atop a cleared, fully transparent buffer, it's |
| // unnecessary; but if we're decoding an interlaced gif and |
| // displaying it "Haeberli"-style, we must write these for passes |
| // beyond the first, or the initial passes will "show through" the |
| // later ones. |
| if (writeTransparentPixels) |
| buffer.backingStore()->setPixel(currentAddress, 0, 0, 0, 0); |
| } |
| ++currentAddress; |
| } |
| |
| // Tell the frame to copy the row data if need be. |
| if (repeatCount > 1) |
| buffer.backingStore()->repeatFirstRow(IntRect(xBegin, yBegin, xEnd - xBegin , yEnd - yBegin)); |
| |
| return true; |
| } |
| |
| bool GIFImageDecoder::frameComplete(unsigned frameIndex, unsigned frameDuration, ScalableImageDecoderFrame::DisposalMethod disposalMethod) |
| { |
| // Initialize the frame if necessary. Some GIFs insert do-nothing frames, |
| // in which case we never reach haveDecodedRow() before getting here. |
| auto& buffer = m_frameBufferCache[frameIndex]; |
| if (buffer.isInvalid() && !initFrameBuffer(frameIndex)) |
| return false; // initFrameBuffer() has already called setFailed(). |
| |
| buffer.setDecodingStatus(DecodingStatus::Complete); |
| buffer.setDuration(Seconds::fromMilliseconds(frameDuration)); |
| buffer.setDisposalMethod(disposalMethod); |
| |
| if (!m_currentBufferSawAlpha) { |
| IntRect rect = buffer.backingStore()->frameRect(); |
| |
| // The whole frame was non-transparent, so it's possible that the entire |
| // resulting buffer was non-transparent, and we can setHasAlpha(false). |
| if (rect.contains(IntRect(IntPoint(), size()))) |
| buffer.setHasAlpha(false); |
| else if (frameIndex) { |
| // Tricky case. This frame does not have alpha only if everywhere |
| // outside its rect doesn't have alpha. To know whether this is |
| // true, we check the start state of the frame -- if it doesn't have |
| // alpha, we're safe. |
| // |
| // First skip over prior DisposalMethod::RestoreToPrevious frames (since they |
| // don't affect the start state of this frame) the same way we do in |
| // initFrameBuffer(). |
| const auto* prevBuffer = &m_frameBufferCache[--frameIndex]; |
| while (frameIndex && (prevBuffer->disposalMethod() == ScalableImageDecoderFrame::DisposalMethod::RestoreToPrevious)) |
| prevBuffer = &m_frameBufferCache[--frameIndex]; |
| |
| // Now, if we're at a DisposalMethod::Unspecified or DisposalMethod::DoNotDispose frame, then |
| // we can say we have no alpha if that frame had no alpha. But |
| // since in initFrameBuffer() we already copied that frame's alpha |
| // state into the current frame's, we need do nothing at all here. |
| // |
| // The only remaining case is a DisposalMethod::RestoreToBackground frame. If |
| // it had no alpha, and its rect is contained in the current frame's |
| // rect, we know the current frame has no alpha. |
| IntRect prevRect = prevBuffer->backingStore()->frameRect(); |
| if ((prevBuffer->disposalMethod() == ScalableImageDecoderFrame::DisposalMethod::RestoreToBackground) && !prevBuffer->hasAlpha() && rect.contains(prevRect)) |
| buffer.setHasAlpha(false); |
| } |
| } |
| |
| return true; |
| } |
| |
| void GIFImageDecoder::gifComplete() |
| { |
| // Cache the repetition count, which is now as authoritative as it's ever |
| // going to be. |
| repetitionCount(); |
| |
| m_reader = nullptr; |
| } |
| |
| void GIFImageDecoder::decode(unsigned haltAtFrame, GIFQuery query, bool allDataReceived) |
| { |
| if (failed()) |
| return; |
| |
| if (!m_reader) { |
| m_reader = makeUnique<GIFImageReader>(this); |
| m_reader->setData(*m_data); |
| } |
| |
| if (query == GIFSizeQuery) { |
| if (!m_reader->decode(GIFSizeQuery, haltAtFrame)) |
| setFailed(); |
| return; |
| } |
| |
| if (!m_reader->decode(GIFFrameCountQuery, haltAtFrame)) { |
| setFailed(); |
| return; |
| } |
| |
| m_frameBufferCache.resize(m_reader->imagesCount()); |
| |
| if (query == GIFFrameCountQuery) |
| return; |
| |
| if (!m_reader->decode(GIFFullQuery, haltAtFrame)) { |
| setFailed(); |
| return; |
| } |
| |
| // It is also a fatal error if all data is received but we failed to decode |
| // all frames completely. |
| if (allDataReceived && haltAtFrame >= m_frameBufferCache.size() && m_reader) |
| setFailed(); |
| } |
| |
| bool GIFImageDecoder::initFrameBuffer(unsigned frameIndex) |
| { |
| // Initialize the frame rect in our buffer. |
| const GIFFrameContext* frameContext = m_reader->frameContext(); |
| IntRect frameRect(frameContext->xOffset, frameContext->yOffset, frameContext->width, frameContext->height); |
| auto* const buffer = &m_frameBufferCache[frameIndex]; |
| |
| if (!frameIndex) { |
| // This is the first frame, so we're not relying on any previous data. |
| if (!buffer->initialize(size(), m_premultiplyAlpha)) |
| return setFailed(); |
| } else { |
| // The starting state for this frame depends on the previous frame's |
| // disposal method. |
| // |
| // Frames that use the DisposalMethod::RestoreToPrevious method are effectively |
| // no-ops in terms of changing the starting state of a frame compared to |
| // the starting state of the previous frame, so skip over them. (If the |
| // first frame specifies this method, it will get treated like |
| // DisposalMethod::RestoreToBackground below and reset to a completely empty image.) |
| const auto* prevBuffer = &m_frameBufferCache[--frameIndex]; |
| auto prevMethod = prevBuffer->disposalMethod(); |
| while (frameIndex && (prevMethod == ScalableImageDecoderFrame::DisposalMethod::RestoreToPrevious)) { |
| prevBuffer = &m_frameBufferCache[--frameIndex]; |
| prevMethod = prevBuffer->disposalMethod(); |
| } |
| |
| ASSERT(prevBuffer->isComplete()); |
| |
| if ((prevMethod == ScalableImageDecoderFrame::DisposalMethod::Unspecified) || (prevMethod == ScalableImageDecoderFrame::DisposalMethod::DoNotDispose)) { |
| // Preserve the last frame as the starting state for this frame. |
| if (!prevBuffer->backingStore() || !buffer->initialize(*prevBuffer->backingStore())) |
| return setFailed(); |
| } else { |
| // We want to clear the previous frame to transparent, without |
| // affecting pixels in the image outside of the frame. |
| IntRect prevRect = prevBuffer->backingStore()->frameRect(); |
| const IntSize& bufferSize = size(); |
| if (!frameIndex || prevRect.contains(IntRect(IntPoint(), size()))) { |
| // Clearing the first frame, or a frame the size of the whole |
| // image, results in a completely empty image. |
| if (!buffer->initialize(bufferSize, m_premultiplyAlpha)) |
| return setFailed(); |
| } else { |
| // Copy the whole previous buffer, then clear just its frame. |
| if (!prevBuffer->backingStore() || !buffer->initialize(*prevBuffer->backingStore())) |
| return setFailed(); |
| buffer->backingStore()->clearRect(prevRect); |
| buffer->setHasAlpha(true); |
| } |
| } |
| } |
| |
| // Make sure the frameRect doesn't extend outside the buffer. |
| if (frameRect.maxX() > size().width()) |
| frameRect.setWidth(size().width() - frameContext->xOffset); |
| if (frameRect.maxY() > size().height()) |
| frameRect.setHeight(size().height() - frameContext->yOffset); |
| |
| buffer->backingStore()->setFrameRect(frameRect); |
| |
| // Update our status to be partially complete. |
| buffer->setDecodingStatus(DecodingStatus::Partial); |
| |
| // Reset the alpha pixel tracker for this frame. |
| m_currentBufferSawAlpha = false; |
| return true; |
| } |
| |
| } // namespace WebCore |
