/* * Copyright (C) 2006 Apple Computer, Inc. All rights reserved. * Copyright (C) 2008, 2009 Google, Inc. * * 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 COMPUTER, 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 COMPUTER, 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" namespace WebCore { class GIFImageDecoderPrivate { public: GIFImageDecoderPrivate(GIFImageDecoder* decoder = 0) : m_reader(decoder) , m_readOffset(0) { } ~GIFImageDecoderPrivate() { m_reader.close(); } bool decode(SharedBuffer* data, GIFImageDecoder::GIFQuery query = GIFImageDecoder::GIFFullQuery, unsigned int haltFrame = -1) { return m_reader.read((const unsigned char*)data->data() + m_readOffset, data->size() - m_readOffset, query, haltFrame); } unsigned frameCount() const { return m_reader.images_count; } int repetitionCount() const { return m_reader.loop_count; } void setReadOffset(unsigned o) { m_readOffset = o; } bool isTransparent() const { return m_reader.frame_reader->is_transparent; } void getColorMap(unsigned char*& map, unsigned& size) const { if (m_reader.frame_reader->is_local_colormap_defined) { map = m_reader.frame_reader->local_colormap; size = (unsigned)m_reader.frame_reader->local_colormap_size; } else { map = m_reader.global_colormap; size = m_reader.global_colormap_size; } } unsigned frameXOffset() const { return m_reader.frame_reader->x_offset; } unsigned frameYOffset() const { return m_reader.frame_reader->y_offset; } unsigned frameWidth() const { return m_reader.frame_reader->width; } unsigned frameHeight() const { return m_reader.frame_reader->height; } int transparentPixel() const { return m_reader.frame_reader->tpixel; } unsigned duration() const { return m_reader.frame_reader->delay_time; } private: GIFImageReader m_reader; unsigned m_readOffset; }; GIFImageDecoder::GIFImageDecoder() : m_frameCountValid(true) , m_repetitionCount(cAnimationLoopOnce) , m_reader(0) { } GIFImageDecoder::~GIFImageDecoder() { delete m_reader; } // Take the data and store it. void GIFImageDecoder::setData(SharedBuffer* data, bool allDataReceived) { if (m_failed) return; // Cache our new data. ImageDecoder::setData(data, allDataReceived); // Our frame count is now unknown. m_frameCountValid = false; // Create the GIF reader. if (!m_reader && !m_failed) m_reader = new GIFImageDecoderPrivate(this); } // Whether or not the size information has been decoded yet. bool GIFImageDecoder::isSizeAvailable() const { // If we have pending data to decode, send it to the GIF reader now. if (!ImageDecoder::isSizeAvailable() && m_reader) { if (m_failed) return false; // The decoder will go ahead and aggressively consume everything up until the first // size is encountered. decode(GIFSizeQuery, 0); } return !m_failed && ImageDecoder::isSizeAvailable(); } // The total number of frames for the image. Will scan the image data for the answer // (without necessarily decoding all of the individual frames). int GIFImageDecoder::frameCount() { // If the decoder had an earlier error, we will just return what we had decoded // so far. if (!m_frameCountValid) { // FIXME: Scanning all the data has O(n^2) behavior if the data were to come in really // slowly. Might be interesting to try to clone our existing read session to preserve // state, but for now we just crawl all the data. Note that this is no worse than what // ImageIO does on Mac right now (it also crawls all the data again). GIFImageDecoderPrivate reader; // This function may fail, but we want to keep any partial data it may // have decoded, so don't mark it is invalid. If there is an overflow // or some serious error, m_failed will have gotten set for us. reader.decode(m_data.get(), GIFFrameCountQuery); m_frameCountValid = true; m_frameBufferCache.resize(reader.frameCount()); } return m_frameBufferCache.size(); } // The number of repetitions to perform for an animation loop. int 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. Our caller is // responsible for waiting until image decoding has finished to ask this if // it needs an authoritative answer. In the meantime, we should default to // "loop once". if (m_reader) { // Added wrinkle: ImageSource::clear() may destroy the reader, making // the result from the reader _less_ authoritative on future calls. To // detect this, the reader returns cLoopCountNotSeen (-2) instead of // cAnimationLoopOnce (-1) when its current incarnation hasn't actually // seen a loop count yet; in this case we return our previously-cached // value. const int repetitionCount = m_reader->repetitionCount(); if (repetitionCount != cLoopCountNotSeen) m_repetitionCount = repetitionCount; } return m_repetitionCount; } RGBA32Buffer* GIFImageDecoder::frameBufferAtIndex(size_t index) { if (index >= static_cast<size_t>(frameCount())) return 0; RGBA32Buffer& frame = m_frameBufferCache[index]; if (frame.status() != RGBA32Buffer::FrameComplete && m_reader) decode(GIFFullQuery, index+1); // Decode this frame. return &frame; } 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<RGBA32Buffer>::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 DisposeOverwritePrevious, 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 DisposeOverwritePrevious, stop // scanning, as we'll only need this frame when decoding the next one. Vector<RGBA32Buffer>::iterator i(end); for (; (i != m_frameBufferCache.begin()) && ((i->status() == RGBA32Buffer::FrameEmpty) || (i->disposalMethod() == RGBA32Buffer::DisposeOverwritePrevious)); --i) { if ((i->status() == RGBA32Buffer::FrameComplete) && (i != end)) i->clear(); } // Now |i| holds the last frame we need to preserve; clear prior frames. for (Vector<RGBA32Buffer>::iterator j(m_frameBufferCache.begin()); j != i; ++j) { ASSERT(j->status() != RGBA32Buffer::FramePartial); if (j->status() != RGBA32Buffer::FrameEmpty) j->clear(); } } // Feed data to the GIF reader. void GIFImageDecoder::decode(GIFQuery query, unsigned haltAtFrame) const { if (m_failed) return; m_failed = !m_reader->decode(m_data.get(), query, haltAtFrame); if (m_failed) { delete m_reader; m_reader = 0; } } // Callbacks from the GIF reader. bool GIFImageDecoder::sizeNowAvailable(unsigned width, unsigned height) { return setSize(width, height); } void GIFImageDecoder::decodingHalted(unsigned bytesLeft) { m_reader->setReadOffset(m_data->size() - bytesLeft); } bool GIFImageDecoder::initFrameBuffer(unsigned frameIndex) { // Initialize the frame rect in our buffer. IntRect frameRect(m_reader->frameXOffset(), m_reader->frameYOffset(), m_reader->frameWidth(), m_reader->frameHeight()); // Make sure the frameRect doesn't extend past the bottom-right of the buffer. if (frameRect.right() > size().width()) frameRect.setWidth(size().width() - m_reader->frameXOffset()); if (frameRect.bottom() > size().height()) frameRect.setHeight(size().height() - m_reader->frameYOffset()); RGBA32Buffer* const buffer = &m_frameBufferCache[frameIndex]; buffer->setRect(frameRect); if (frameIndex == 0) { // This is the first frame, so we're not relying on any previous data. if (!prepEmptyFrameBuffer(buffer)) { buffer->setStatus(RGBA32Buffer::FrameComplete); m_failed = true; return false; } } else { // The starting state for this frame depends on the previous frame's // disposal method. // // Frames that use the DisposeOverwritePrevious 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 // DisposeOverwriteBgcolor below and reset to a completely empty image.) const RGBA32Buffer* prevBuffer = &m_frameBufferCache[--frameIndex]; RGBA32Buffer::FrameDisposalMethod prevMethod = prevBuffer->disposalMethod(); while ((frameIndex > 0) && (prevMethod == RGBA32Buffer::DisposeOverwritePrevious)) { prevBuffer = &m_frameBufferCache[--frameIndex]; prevMethod = prevBuffer->disposalMethod(); } ASSERT(prevBuffer->status() == RGBA32Buffer::FrameComplete); if ((prevMethod == RGBA32Buffer::DisposeNotSpecified) || (prevMethod == RGBA32Buffer::DisposeKeep)) { // Preserve the last frame as the starting state for this frame. buffer->copyBitmapData(*prevBuffer); // This next line isn't currently necessary since the alpha state is // currently carried along in the Skia bitmap data, but it's safe, // future-proof, and parallel to the Cairo code. buffer->setHasAlpha(prevBuffer->hasAlpha()); } else { // We want to clear the previous frame to transparent, without // affecting pixels in the image outside of the frame. const IntRect& prevRect = prevBuffer->rect(); if ((frameIndex == 0) || prevRect.contains(IntRect(IntPoint(0, 0), size()))) { // Clearing the first frame, or a frame the size of the whole // image, results in a completely empty image. prepEmptyFrameBuffer(buffer); } else { // Copy the whole previous buffer, then clear just its frame. buffer->copyBitmapData(*prevBuffer); // Unnecessary (but safe); see comments on the similar call above. buffer->setHasAlpha(prevBuffer->hasAlpha()); SkBitmap& bitmap = buffer->bitmap(); for (int y = prevRect.y(); y < prevRect.bottom(); ++y) { for (int x = prevRect.x(); x < prevRect.right(); ++x) buffer->setRGBA(bitmap.getAddr32(x, y), 0, 0, 0, 0); } if ((prevRect.width() > 0) && (prevRect.height() > 0)) buffer->setHasAlpha(true); } } } // Update our status to be partially complete. buffer->setStatus(RGBA32Buffer::FramePartial); // Reset the alpha pixel tracker for this frame. m_currentBufferSawAlpha = false; return true; } bool GIFImageDecoder::prepEmptyFrameBuffer(RGBA32Buffer* buffer) const { if (!buffer->setSize(size().width(), size().height())) return false; // This next line isn't currently necessary since Skia's eraseARGB() sets // this for us, but we do it for similar reasons to the setHasAlpha() calls // in initFrameBuffer() above. buffer->setHasAlpha(true); return true; } void GIFImageDecoder::haveDecodedRow(unsigned frameIndex, unsigned char* rowBuffer, // Pointer to single scanline temporary buffer unsigned char* rowEnd, unsigned rowNumber, // The row index unsigned repeatCount, // How many times to repeat the row bool writeTransparentPixels) { // Initialize the frame if necessary. RGBA32Buffer& buffer = m_frameBufferCache[frameIndex]; if ((buffer.status() == RGBA32Buffer::FrameEmpty) && !initFrameBuffer(frameIndex)) return; // Do nothing for bogus data. if (rowBuffer == 0 || static_cast<int>(m_reader->frameYOffset() + rowNumber) >= size().height()) return; unsigned colorMapSize; unsigned char* colorMap; m_reader->getColorMap(colorMap, colorMapSize); if (!colorMap) return; // The buffers that we draw are the entire image's width and height, so a final output frame is // width * height RGBA32 values in size. // // A single GIF frame, however, can be smaller than the entire image, i.e., it can represent some sub-rectangle // within the overall image. The rows we are decoding are within this // sub-rectangle. This means that if the GIF frame's sub-rectangle is (x,y,w,h) then row 0 is really row // y, and each row goes from x to x+w. unsigned dstPos = (m_reader->frameYOffset() + rowNumber) * size().width() + m_reader->frameXOffset(); unsigned* dst = buffer.bitmap().getAddr32(0, 0) + dstPos; unsigned* dstEnd = dst + size().width() - m_reader->frameXOffset(); unsigned* currDst = dst; unsigned char* currentRowByte = rowBuffer; while (currentRowByte != rowEnd && currDst < dstEnd) { if ((!m_reader->isTransparent() || *currentRowByte != m_reader->transparentPixel()) && *currentRowByte < colorMapSize) { unsigned colorIndex = *currentRowByte * 3; unsigned red = colorMap[colorIndex]; unsigned green = colorMap[colorIndex + 1]; unsigned blue = colorMap[colorIndex + 2]; RGBA32Buffer::setRGBA(currDst, red, green, blue, 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) RGBA32Buffer::setRGBA(currDst, 0, 0, 0, 0); } currDst++; currentRowByte++; } if (repeatCount > 1) { // Copy the row |repeatCount|-1 times. unsigned num = currDst - dst; unsigned data_size = num * sizeof(unsigned); unsigned width = size().width(); unsigned* end = buffer.bitmap().getAddr32(0, 0) + width * size().height(); currDst = dst + width; for (unsigned i = 1; i < repeatCount; i++) { if (currDst + num > end) // Protect against a buffer overrun from a bogus repeatCount. break; memcpy(currDst, dst, data_size); currDst += width; } } } void GIFImageDecoder::frameComplete(unsigned frameIndex, unsigned frameDuration, RGBA32Buffer::FrameDisposalMethod disposalMethod) { // Initialize the frame if necessary. Some GIFs insert do-nothing frames, // in which case we never reach haveDecodedRow() before getting here. RGBA32Buffer& buffer = m_frameBufferCache[frameIndex]; if ((buffer.status() == RGBA32Buffer::FrameEmpty) && !initFrameBuffer(frameIndex)) return; buffer.setStatus(RGBA32Buffer::FrameComplete); buffer.setDuration(frameDuration); buffer.setDisposalMethod(disposalMethod); if (!m_currentBufferSawAlpha) { // The whole frame was non-transparent, so it's possible that the entire // resulting buffer was non-transparent, and we can setHasAlpha(false). if (buffer.rect().contains(IntRect(IntPoint(0, 0), size()))) buffer.setHasAlpha(false); else if (frameIndex > 0) { // 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 DisposeOverwritePrevious frames (since they // don't affect the start state of this frame) the same way we do in // initFrameBuffer(). const RGBA32Buffer* prevBuffer = &m_frameBufferCache[--frameIndex]; while ((frameIndex > 0) && (prevBuffer->disposalMethod() == RGBA32Buffer::DisposeOverwritePrevious)) prevBuffer = &m_frameBufferCache[--frameIndex]; // Now, if we're at a DisposeNotSpecified or DisposeKeep 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 DisposeOverwriteBgcolor 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. if ((prevBuffer->disposalMethod() == RGBA32Buffer::DisposeOverwriteBgcolor) && !prevBuffer->hasAlpha() && buffer.rect().contains(prevBuffer->rect())) buffer.setHasAlpha(false); } } } void GIFImageDecoder::gifComplete() { if (m_reader) m_repetitionCount = m_reader->repetitionCount(); delete m_reader; m_reader = 0; } } // namespace WebCore