--- a/src/plugins/imageformats/gif/qgifhandler.cpp Mon Mar 15 12:43:09 2010 +0200
+++ b/src/plugins/imageformats/gif/qgifhandler.cpp Thu Apr 08 14:19:33 2010 +0300
@@ -71,7 +71,8 @@
~QGIFFormat();
int decode(QImage *image, const uchar* buffer, int length,
- int *nextFrameDelay, int *loopCount, QSize *nextSize);
+ int *nextFrameDelay, int *loopCount);
+ static void scan(QIODevice *device, QVector<QSize> *imageSizes, int *loopCount);
bool newFrame;
bool partialNewFrame;
@@ -229,7 +230,7 @@
Returns the number of bytes consumed.
*/
int QGIFFormat::decode(QImage *image, const uchar *buffer, int length,
- int *nextFrameDelay, int *loopCount, QSize *nextSize)
+ int *nextFrameDelay, int *loopCount)
{
// We are required to state that
// "The Graphics Interchange Format(c) is the Copyright property of
@@ -346,10 +347,6 @@
bpl = image->bytesPerLine();
bits = image->bits();
memset(bits, 0, image->byteCount());
-
- // ### size of the upcoming frame, should rather
- // be known before decoding it.
- *nextSize = QSize(swidth, sheight);
}
disposePrevious(image);
@@ -645,6 +642,273 @@
return initial-length;
}
+/*!
+ Scans through the data stream defined by \a device and returns the image
+ sizes found in the stream in the \a imageSizes vector.
+*/
+void QGIFFormat::scan(QIODevice *device, QVector<QSize> *imageSizes, int *loopCount)
+{
+ if (!device)
+ return;
+
+ qint64 oldPos = device->pos();
+ if (!device->seek(0))
+ return;
+
+ int colorCount = 0;
+ int localColorCount = 0;
+ int globalColorCount = 0;
+ int colorReadCount = 0;
+ bool localColormap = false;
+ bool globalColormap = false;
+ int count = 0;
+ int blockSize = 0;
+ int imageWidth = 0;
+ int imageHeight = 0;
+ bool done = false;
+ uchar hold[16];
+ State state = Header;
+
+ const int readBufferSize = 40960; // 40k read buffer
+ QByteArray readBuffer(device->read(readBufferSize));
+
+ if (readBuffer.isEmpty()) {
+ device->seek(oldPos);
+ return;
+ }
+
+ // This is a specialized version of the state machine from decode(),
+ // which doesn't do any image decoding or mallocing, and has an
+ // optimized way of skipping SkipBlocks, ImageDataBlocks and
+ // Global/LocalColorMaps.
+
+ while (!readBuffer.isEmpty()) {
+ int length = readBuffer.size();
+ const uchar *buffer = (const uchar *) readBuffer.constData();
+ while (!done && length) {
+ length--;
+ uchar ch = *buffer++;
+ switch (state) {
+ case Header:
+ hold[count++] = ch;
+ if (count == 6) {
+ state = LogicalScreenDescriptor;
+ count = 0;
+ }
+ break;
+ case LogicalScreenDescriptor:
+ hold[count++] = ch;
+ if (count == 7) {
+ imageWidth = LM(hold[0], hold[1]);
+ imageHeight = LM(hold[2], hold[3]);
+ globalColormap = !!(hold[4] & 0x80);
+ globalColorCount = 2 << (hold[4] & 0x7);
+ count = 0;
+ colorCount = globalColorCount;
+ if (globalColormap) {
+ int colorTableSize = 3 * globalColorCount;
+ if (length >= colorTableSize) {
+ // skip the global color table in one go
+ length -= colorTableSize;
+ buffer += colorTableSize;
+ state = Introducer;
+ } else {
+ colorReadCount = 0;
+ state = GlobalColorMap;
+ }
+ } else {
+ state=Introducer;
+ }
+ }
+ break;
+ case GlobalColorMap:
+ case LocalColorMap:
+ hold[count++] = ch;
+ if (count == 3) {
+ if (++colorReadCount >= colorCount) {
+ if (state == LocalColorMap)
+ state = TableImageLZWSize;
+ else
+ state = Introducer;
+ }
+ count = 0;
+ }
+ break;
+ case Introducer:
+ hold[count++] = ch;
+ switch (ch) {
+ case 0x2c:
+ state = ImageDescriptor;
+ break;
+ case 0x21:
+ state = ExtensionLabel;
+ break;
+ case 0x3b:
+ state = Done;
+ break;
+ default:
+ done = true;
+ state = Error;
+ }
+ break;
+ case ImageDescriptor:
+ hold[count++] = ch;
+ if (count == 10) {
+ int newLeft = LM(hold[1], hold[2]);
+ int newTop = LM(hold[3], hold[4]);
+ int newWidth = LM(hold[5], hold[6]);
+ int newHeight = LM(hold[7], hold[8]);
+
+ if (imageWidth/10 > qMax(newWidth,200))
+ imageWidth = -1;
+ if (imageHeight/10 > qMax(newHeight,200))
+ imageHeight = -1;
+
+ if (imageWidth <= 0)
+ imageWidth = newLeft + newWidth;
+ if (imageHeight <= 0)
+ imageHeight = newTop + newHeight;
+
+ *imageSizes << QSize(imageWidth, imageHeight);
+
+ localColormap = !!(hold[9] & 0x80);
+ localColorCount = localColormap ? (2 << (hold[9] & 0x7)) : 0;
+ if (localColorCount)
+ colorCount = localColorCount;
+ else
+ colorCount = globalColorCount;
+
+ count = 0;
+ if (localColormap) {
+ int colorTableSize = 3 * localColorCount;
+ if (length >= colorTableSize) {
+ // skip the local color table in one go
+ length -= colorTableSize;
+ buffer += colorTableSize;
+ state = TableImageLZWSize;
+ } else {
+ colorReadCount = 0;
+ state = LocalColorMap;
+ }
+ } else {
+ state = TableImageLZWSize;
+ }
+ }
+ break;
+ case TableImageLZWSize:
+ if (ch > max_lzw_bits)
+ state = Error;
+ else
+ state = ImageDataBlockSize;
+ count = 0;
+ break;
+ case ImageDataBlockSize:
+ blockSize = ch;
+ if (blockSize) {
+ if (length >= blockSize) {
+ // we can skip the block in one go
+ length -= blockSize;
+ buffer += blockSize;
+ count = 0;
+ } else {
+ state = ImageDataBlock;
+ }
+ } else {
+ state = Introducer;
+ }
+ break;
+ case ImageDataBlock:
+ ++count;
+ if (count == blockSize) {
+ count = 0;
+ state = ImageDataBlockSize;
+ }
+ break;
+ case ExtensionLabel:
+ switch (ch) {
+ case 0xf9:
+ state = GraphicControlExtension;
+ break;
+ case 0xff:
+ state = ApplicationExtension;
+ break;
+ default:
+ state = SkipBlockSize;
+ }
+ count = 0;
+ break;
+ case ApplicationExtension:
+ if (count < 11)
+ hold[count] = ch;
+ ++count;
+ if (count == hold[0] + 1) {
+ if (qstrncmp((char*)(hold+1), "NETSCAPE", 8) == 0)
+ state=NetscapeExtensionBlockSize;
+ else
+ state=SkipBlockSize;
+ count = 0;
+ }
+ break;
+ case GraphicControlExtension:
+ if (count < 5)
+ hold[count] = ch;
+ ++count;
+ if (count == hold[0] + 1) {
+ count = 0;
+ state = SkipBlockSize;
+ }
+ break;
+ case NetscapeExtensionBlockSize:
+ blockSize = ch;
+ count = 0;
+ if (blockSize)
+ state = NetscapeExtensionBlock;
+ else
+ state = Introducer;
+ break;
+ case NetscapeExtensionBlock:
+ if (count < 3)
+ hold[count] = ch;
+ count++;
+ if (count == blockSize) {
+ *loopCount = LM(hold[1], hold[2]);
+ state = SkipBlockSize;
+ }
+ break;
+ case SkipBlockSize:
+ blockSize = ch;
+ count = 0;
+ if (blockSize) {
+ if (length >= blockSize) {
+ // we can skip the block in one go
+ length -= blockSize;
+ buffer += blockSize;
+ } else {
+ state = SkipBlock;
+ }
+ } else {
+ state = Introducer;
+ }
+ break;
+ case SkipBlock:
+ ++count;
+ if (count == blockSize)
+ state = SkipBlockSize;
+ break;
+ case Done:
+ done = true;
+ break;
+ case Error:
+ device->seek(oldPos);
+ return;
+ }
+ }
+ readBuffer = device->read(readBufferSize);
+ }
+ device->seek(oldPos);
+ return;
+}
+
void QGIFFormat::fillRect(QImage *image, int col, int row, int w, int h, QRgb color)
{
if (w>0) {
@@ -763,9 +1027,9 @@
{
gifFormat = new QGIFFormat;
nextDelay = 0;
- loopCnt = 0;
+ loopCnt = 1;
frameNumber = -1;
- nextSize = QSize();
+ scanIsCached = false;
}
QGifHandler::~QGifHandler()
@@ -787,7 +1051,7 @@
}
int decoded = gifFormat->decode(&lastImage, (const uchar *)buffer.constData(), buffer.size(),
- &nextDelay, &loopCnt, &nextSize);
+ &nextDelay, &loopCnt);
if (decoded == -1)
break;
buffer.remove(0, decoded);
@@ -831,7 +1095,7 @@
}
int decoded = gifFormat->decode(&lastImage, (const uchar *)buffer.constData(), buffer.size(),
- &nextDelay, &loopCnt, &nextSize);
+ &nextDelay, &loopCnt);
if (decoded == -1)
break;
buffer.remove(0, decoded);
@@ -862,8 +1126,18 @@
QVariant QGifHandler::option(ImageOption option) const
{
if (option == Size) {
- if (imageIsComing())
- return nextSize;
+ if (!scanIsCached) {
+ QGIFFormat::scan(device(), &imageSizes, &loopCnt);
+ scanIsCached = true;
+ }
+ // before the first frame is read, or we have an empty data stream
+ if (frameNumber == -1)
+ return (imageSizes.count() > 0) ? QVariant(imageSizes.at(0)) : QVariant();
+ // after the last frame has been read, the next size is undefined
+ if (frameNumber >= imageSizes.count() - 1)
+ return QVariant();
+ // and the last case: the size of the next frame
+ return imageSizes.at(frameNumber + 1);
} else if (option == Animation) {
return true;
}
@@ -883,11 +1157,19 @@
int QGifHandler::imageCount() const
{
- return 0; // Don't know
+ if (!scanIsCached) {
+ QGIFFormat::scan(device(), &imageSizes, &loopCnt);
+ scanIsCached = true;
+ }
+ return imageSizes.count();
}
int QGifHandler::loopCount() const
{
+ if (!scanIsCached) {
+ QGIFFormat::scan(device(), &imageSizes, &loopCnt);
+ scanIsCached = true;
+ }
return loopCnt-1; // In GIF, loop count is iteration count, so subtract one
}