diff -r 000000000000 -r 1918ee327afb src/plugins/imageformats/gif/qgifhandler.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/plugins/imageformats/gif/qgifhandler.cpp	Mon Jan 11 14:00:40 2010 +0000
@@ -0,0 +1,892 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the plugins of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights.  These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+** WARNING:
+**      A separate license from Unisys may be required to use the gif
+**      reader. See http://www.unisys.com/about__unisys/lzw/
+**      for information from Unisys
+**
+****************************************************************************/
+
+#include "qgifhandler.h"
+
+#include <qimage.h>
+#include <qiodevice.h>
+#include <qvariant.h>
+
+QT_BEGIN_NAMESPACE
+
+#define Q_TRANSPARENT 0x00ffffff
+
+/*
+  Incremental image decoder for GIF image format.
+
+  This subclass of QImageFormat decodes GIF format images,
+  including animated GIFs. Internally in
+*/
+
+class QGIFFormat {
+public:
+    QGIFFormat();
+    ~QGIFFormat();
+
+    int decode(QImage *image, const uchar* buffer, int length,
+               int *nextFrameDelay, int *loopCount, QSize *nextSize);
+
+    bool newFrame;
+    bool partialNewFrame;
+
+private:
+    void fillRect(QImage *image, int x, int y, int w, int h, QRgb col);
+    inline QRgb color(uchar index) const;
+
+    // GIF specific stuff
+    QRgb* globalcmap;
+    QRgb* localcmap;
+    QImage backingstore;
+    unsigned char hold[16];
+    bool gif89;
+    int count;
+    int ccount;
+    int expectcount;
+    enum State {
+        Header,
+        LogicalScreenDescriptor,
+        GlobalColorMap,
+        LocalColorMap,
+        Introducer,
+        ImageDescriptor,
+        TableImageLZWSize,
+        ImageDataBlockSize,
+        ImageDataBlock,
+        ExtensionLabel,
+        GraphicControlExtension,
+        ApplicationExtension,
+        NetscapeExtensionBlockSize,
+        NetscapeExtensionBlock,
+        SkipBlockSize,
+        SkipBlock,
+        Done,
+        Error
+    } state;
+    int gncols;
+    int lncols;
+    int ncols;
+    int lzwsize;
+    bool lcmap;
+    int swidth, sheight;
+    int width, height;
+    int left, top, right, bottom;
+    enum Disposal { NoDisposal, DoNotChange, RestoreBackground, RestoreImage };
+    Disposal disposal;
+    bool disposed;
+    int trans_index;
+    bool gcmap;
+    int bgcol;
+    int interlace;
+    int accum;
+    int bitcount;
+
+    enum { max_lzw_bits=12 }; // (poor-compiler's static const int)
+
+    int code_size, clear_code, end_code, max_code_size, max_code;
+    int firstcode, oldcode, incode;
+    short table[2][1<< max_lzw_bits];
+    short stack[(1<<(max_lzw_bits))*2];
+    short *sp;
+    bool needfirst;
+    int x, y;
+    int frame;
+    bool out_of_bounds;
+    bool digress;
+    void nextY(QImage *image);
+    void disposePrevious(QImage *image);
+};
+
+/*!
+    Constructs a QGIFFormat.
+*/
+QGIFFormat::QGIFFormat()
+{
+    globalcmap = 0;
+    localcmap = 0;
+    lncols = 0;
+    gncols = 0;
+    disposal = NoDisposal;
+    out_of_bounds = false;
+    disposed = true;
+    frame = -1;
+    state = Header;
+    count = 0;
+    lcmap = false;
+    newFrame = false;
+    partialNewFrame = false;
+}
+
+/*!
+    Destroys a QGIFFormat.
+*/
+QGIFFormat::~QGIFFormat()
+{
+    if (globalcmap) delete[] globalcmap;
+    if (localcmap) delete[] localcmap;
+}
+
+void QGIFFormat::disposePrevious(QImage *image)
+{
+    if (out_of_bounds) {
+        // flush anything that survived
+        // ### Changed: QRect(0, 0, swidth, sheight)
+    }
+
+    // Handle disposal of previous image before processing next one
+
+    if (disposed) return;
+
+    int l = qMin(swidth-1,left);
+    int r = qMin(swidth-1,right);
+    int t = qMin(sheight-1,top);
+    int b = qMin(sheight-1,bottom);
+
+    switch (disposal) {
+      case NoDisposal:
+        break;
+      case DoNotChange:
+        break;
+      case RestoreBackground:
+        if (trans_index>=0) {
+            // Easy:  we use the transparent color
+            fillRect(image, l, t, r-l+1, b-t+1, Q_TRANSPARENT);
+        } else if (bgcol>=0) {
+            // Easy:  we use the bgcol given
+            fillRect(image, l, t, r-l+1, b-t+1, color(bgcol));
+        } else {
+            // Impossible:  We don't know of a bgcol - use pixel 0
+            QRgb *bits = (QRgb*)image->bits();
+            fillRect(image, l, t, r-l+1, b-t+1, bits[0]);
+        }
+        // ### Changed: QRect(l, t, r-l+1, b-t+1)
+        break;
+      case RestoreImage: {
+        if (frame >= 0) {
+            for (int ln=t; ln<=b; ln++) {
+                memcpy(image->scanLine(ln)+l,
+                    backingstore.scanLine(ln-t),
+                    (r-l+1)*sizeof(QRgb));
+            }
+            // ### Changed: QRect(l, t, r-l+1, b-t+1)
+        }
+      }
+    }
+    disposal = NoDisposal; // Until an extension says otherwise.
+
+    disposed = true;
+}
+
+/*!
+    This function decodes some data into image changes.
+
+    Returns the number of bytes consumed.
+*/
+int QGIFFormat::decode(QImage *image, const uchar *buffer, int length,
+                       int *nextFrameDelay, int *loopCount, QSize *nextSize)
+{
+    // We are required to state that
+    //    "The Graphics Interchange Format(c) is the Copyright property of
+    //    CompuServe Incorporated. GIF(sm) is a Service Mark property of
+    //    CompuServe Incorporated."
+
+#define LM(l, m) (((m)<<8)|l)
+    digress = false;
+    const int initial = length;
+    while (!digress && length) {
+        length--;
+        unsigned char ch=*buffer++;
+        switch (state) {
+          case Header:
+            hold[count++]=ch;
+            if (count==6) {
+                // Header
+                gif89=(hold[3]!='8' || hold[4]!='7');
+                state=LogicalScreenDescriptor;
+                count=0;
+            }
+            break;
+          case LogicalScreenDescriptor:
+            hold[count++]=ch;
+            if (count==7) {
+                // Logical Screen Descriptor
+                swidth=LM(hold[0], hold[1]);
+                sheight=LM(hold[2], hold[3]);
+                gcmap=!!(hold[4]&0x80);
+                //UNUSED: bpchan=(((hold[4]&0x70)>>3)+1);
+                //UNUSED: gcmsortflag=!!(hold[4]&0x08);
+                gncols=2<<(hold[4]&0x7);
+                bgcol=(gcmap) ? hold[5] : -1;
+                //aspect=hold[6] ? double(hold[6]+15)/64.0 : 1.0;
+
+                trans_index = -1;
+                count=0;
+                ncols=gncols;
+                if (gcmap) {
+                    ccount=0;
+                    state=GlobalColorMap;
+                    globalcmap = new QRgb[gncols+1]; // +1 for trans_index
+                    globalcmap[gncols] = Q_TRANSPARENT;
+                } else {
+                    state=Introducer;
+                }
+            }
+            break;
+          case GlobalColorMap: case LocalColorMap:
+            hold[count++]=ch;
+            if (count==3) {
+                QRgb rgb = qRgb(hold[0], hold[1], hold[2]);
+                if (state == LocalColorMap) {
+                    if (ccount < lncols)
+                        localcmap[ccount] =  rgb;
+                } else {
+                    globalcmap[ccount] = rgb;
+                }
+                if (++ccount >= ncols) {
+                    if (state == LocalColorMap)
+                        state=TableImageLZWSize;
+                    else
+                        state=Introducer;
+                }
+                count=0;
+            }
+            break;
+          case Introducer:
+            hold[count++]=ch;
+            switch (ch) {
+              case ',':
+                state=ImageDescriptor;
+                break;
+              case '!':
+                state=ExtensionLabel;
+                break;
+              case ';':
+                  // ### Changed: QRect(0, 0, swidth, sheight)
+                state=Done;
+                break;
+              default:
+                digress=true;
+                // Unexpected Introducer - ignore block
+                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]);
+
+                // disbelieve ridiculous logical screen sizes,
+                // unless the image frames are also large.
+                if (swidth/10 > qMax(newwidth,200))
+                    swidth = -1;
+                if (sheight/10 > qMax(newheight,200))
+                    sheight = -1;
+
+                if (swidth <= 0)
+                    swidth = newleft + newwidth;
+                if (sheight <= 0)
+                    sheight = newtop + newheight;
+
+                QImage::Format format = trans_index >= 0 ? QImage::Format_ARGB32 : QImage::Format_RGB32;
+                if (image->isNull()) {
+                    (*image) = QImage(swidth, sheight, format);
+                    memset(image->bits(), 0, image->numBytes());
+
+                    // ### size of the upcoming frame, should rather
+                    // be known before decoding it.
+                    *nextSize = QSize(swidth, sheight);
+                }
+
+                disposePrevious(image);
+                disposed = false;
+
+                left = newleft;
+                top = newtop;
+                width = newwidth;
+                height = newheight;
+
+                right=qMax(0, qMin(left+width, swidth)-1);
+                bottom=qMax(0, qMin(top+height, sheight)-1);
+                lcmap=!!(hold[9]&0x80);
+                interlace=!!(hold[9]&0x40);
+                //bool lcmsortflag=!!(hold[9]&0x20);
+                lncols=lcmap ? (2<<(hold[9]&0x7)) : 0;
+                if (lncols) {
+                    if (localcmap)
+                        delete [] localcmap;
+                    localcmap = new QRgb[lncols+1];
+                    localcmap[lncols] = Q_TRANSPARENT;
+                    ncols = lncols;
+                } else {
+                    ncols = gncols;
+                }
+                frame++;
+                if (frame == 0) {
+                    if (left || top || width<swidth || height<sheight) {
+                        // Not full-size image - erase with bg or transparent
+                        if (trans_index >= 0) {
+                            fillRect(image, 0, 0, swidth, sheight, color(trans_index));
+                            // ### Changed: QRect(0, 0, swidth, sheight)
+                        } else if (bgcol>=0) {
+                            fillRect(image, 0, 0, swidth, sheight, color(bgcol));
+                            // ### Changed: QRect(0, 0, swidth, sheight)
+                        }
+                    }
+                }
+
+                if (disposal == RestoreImage) {
+                    int l = qMin(swidth-1,left);
+                    int r = qMin(swidth-1,right);
+                    int t = qMin(sheight-1,top);
+                    int b = qMin(sheight-1,bottom);
+                    int w = r-l+1;
+                    int h = b-t+1;
+
+                    if (backingstore.width() < w
+                        || backingstore.height() < h) {
+                        // We just use the backing store as a byte array
+                        backingstore = QImage(qMax(backingstore.width(), w),
+                                              qMax(backingstore.height(), h),
+                                              QImage::Format_RGB32);
+                        memset(image->bits(), 0, image->numBytes());
+                    }
+                    for (int ln=0; ln<h; ln++) {
+                        memcpy(backingstore.scanLine(ln),
+                               image->scanLine(t+ln)+l, w*sizeof(QRgb));
+                    }
+                }
+
+                count=0;
+                if (lcmap) {
+                    ccount=0;
+                    state=LocalColorMap;
+                } else {
+                    state=TableImageLZWSize;
+                }
+                x = left;
+                y = top;
+                accum = 0;
+                bitcount = 0;
+                sp = stack;
+                firstcode = oldcode = 0;
+                needfirst = true;
+                out_of_bounds = left>=swidth || y>=sheight;
+            }
+            break;
+          case TableImageLZWSize: {
+            lzwsize=ch;
+            if (lzwsize > max_lzw_bits) {
+                state=Error;
+            } else {
+                code_size=lzwsize+1;
+                clear_code=1<<lzwsize;
+                end_code=clear_code+1;
+                max_code_size=2*clear_code;
+                max_code=clear_code+2;
+                int i;
+                for (i=0; i<clear_code; i++) {
+                    table[0][i]=0;
+                    table[1][i]=i;
+                }
+                state=ImageDataBlockSize;
+            }
+            count=0;
+            break;
+          } case ImageDataBlockSize:
+            expectcount=ch;
+            if (expectcount) {
+                state=ImageDataBlock;
+            } else {
+                state=Introducer;
+                digress = true;
+                newFrame = true;
+            }
+            break;
+          case ImageDataBlock:
+            count++;
+            accum|=(ch<<bitcount);
+            bitcount+=8;
+            while (bitcount>=code_size && state==ImageDataBlock) {
+                int code=accum&((1<<code_size)-1);
+                bitcount-=code_size;
+                accum>>=code_size;
+
+                if (code==clear_code) {
+                    if (!needfirst) {
+                        code_size=lzwsize+1;
+                        max_code_size=2*clear_code;
+                        max_code=clear_code+2;
+                    }
+                    needfirst=true;
+                } else if (code==end_code) {
+                    bitcount = -32768;
+                    // Left the block end arrive
+                } else {
+                    if (needfirst) {
+                        firstcode=oldcode=code;
+                        if (!out_of_bounds && image->height() > y && firstcode!=trans_index)
+                            ((QRgb*)image->scanLine(y))[x] = color(firstcode);
+                        x++;
+                        if (x>=swidth) out_of_bounds = true;
+                        needfirst=false;
+                        if (x>=left+width) {
+                            x=left;
+                            out_of_bounds = left>=swidth || y>=sheight;
+                            nextY(image);
+                        }
+                    } else {
+                        incode=code;
+                        if (code>=max_code) {
+                            *sp++=firstcode;
+                            code=oldcode;
+                        }
+                        while (code>=clear_code+2) {
+                            *sp++=table[1][code];
+                            if (code==table[0][code]) {
+                                state=Error;
+                                break;
+                            }
+                            if (sp-stack>=(1<<(max_lzw_bits))*2) {
+                                state=Error;
+                                break;
+                            }
+                            code=table[0][code];
+                        }
+                        *sp++=firstcode=table[1][code];
+                        code=max_code;
+                        if (code<(1<<max_lzw_bits)) {
+                            table[0][code]=oldcode;
+                            table[1][code]=firstcode;
+                            max_code++;
+                            if ((max_code>=max_code_size)
+                             && (max_code_size<(1<<max_lzw_bits)))
+                            {
+                                max_code_size*=2;
+                                code_size++;
+                            }
+                        }
+                        oldcode=incode;
+                        const int h = image->height();
+                        const QRgb *map = lcmap ? localcmap : globalcmap;
+                        QRgb *line = 0;
+                        if (!out_of_bounds && h > y)
+                            line = (QRgb*)image->scanLine(y);
+                        while (sp>stack) {
+                            const uchar index = *(--sp);
+                            if (!out_of_bounds && h > y && index!=trans_index) {
+                                if (index > ncols)
+                                    line[x] = Q_TRANSPARENT;
+                                else
+                                    line[x] = map ? map[index] : 0;
+                            }
+                            x++;
+                            if (x>=swidth) out_of_bounds = true;
+                            if (x>=left+width) {
+                                x=left;
+                                out_of_bounds = left>=swidth || y>=sheight;
+                                nextY(image);
+                                if (!out_of_bounds && h > y)
+                                    line = (QRgb*)image->scanLine(y);
+                            }
+                        }
+                    }
+                }
+            }
+            partialNewFrame = true;
+            if (count==expectcount) {
+                count=0;
+                state=ImageDataBlockSize;
+            }
+            break;
+          case ExtensionLabel:
+            switch (ch) {
+            case 0xf9:
+                state=GraphicControlExtension;
+                break;
+            case 0xff:
+                state=ApplicationExtension;
+                break;
+#if 0
+            case 0xfe:
+                state=CommentExtension;
+                break;
+            case 0x01:
+                break;
+#endif
+            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) {
+                    // Looping extension
+                    state=NetscapeExtensionBlockSize;
+                } else {
+                    state=SkipBlockSize;
+                }
+                count=0;
+            }
+            break;
+          case NetscapeExtensionBlockSize:
+            expectcount=ch;
+            count=0;
+            if (expectcount) state=NetscapeExtensionBlock;
+            else state=Introducer;
+            break;
+          case NetscapeExtensionBlock:
+            if (count<3) hold[count]=ch;
+            count++;
+            if (count==expectcount) {
+                *loopCount = hold[1]+hold[2]*256;
+                state=SkipBlockSize; // Ignore further blocks
+            }
+            break;
+          case GraphicControlExtension:
+            if (count<5) hold[count]=ch;
+            count++;
+            if (count==hold[0]+1) {
+                disposePrevious(image);
+                disposal=Disposal((hold[1]>>2)&0x7);
+                //UNUSED: waitforuser=!!((hold[1]>>1)&0x1);
+                int delay=count>3 ? LM(hold[2], hold[3]) : 1;
+                // IE and mozilla use a minimum delay of 10. With the minimum delay of 10
+                // we are compatible to them and avoid huge loads on the app and xserver.
+                *nextFrameDelay = (delay < 2 ? 10 : delay) * 10;
+
+                bool havetrans=hold[1]&0x1;
+                trans_index = havetrans ? hold[4] : -1;
+
+                count=0;
+                state=SkipBlockSize;
+            }
+            break;
+          case SkipBlockSize:
+            expectcount=ch;
+            count=0;
+            if (expectcount) state=SkipBlock;
+            else state=Introducer;
+            break;
+          case SkipBlock:
+            count++;
+            if (count==expectcount) state=SkipBlockSize;
+            break;
+          case Done:
+            digress=true;
+            /* Netscape ignores the junk, so we do too.
+            length++; // Unget
+            state=Error; // More calls to this is an error
+            */
+            break;
+          case Error:
+            return -1; // Called again after done.
+        }
+    }
+    return initial-length;
+}
+
+void QGIFFormat::fillRect(QImage *image, int col, int row, int w, int h, QRgb color)
+{
+    if (w>0) {
+        for (int j=0; j<h; j++) {
+            QRgb *line = (QRgb*)image->scanLine(j+row);
+            for (int i=0; i<w; i++)
+                *(line+col+i) = color;
+        }
+    }
+}
+
+void QGIFFormat::nextY(QImage *image)
+{
+    int my;
+    switch (interlace) {
+    case 0: // Non-interlaced
+        // if (!out_of_bounds) {
+        //     ### Changed: QRect(left, y, right - left + 1, 1);
+        // }
+        y++;
+        break;
+    case 1: {
+        int i;
+        my = qMin(7, bottom-y);
+        // Don't dup with transparency
+        if (trans_index < 0) {
+            for (i=1; i<=my; i++) {
+                memcpy(image->scanLine(y+i)+left*sizeof(QRgb), image->scanLine(y)+left*sizeof(QRgb),
+                       (right-left+1)*sizeof(QRgb));
+            }
+        }
+
+        // if (!out_of_bounds) {
+        //     ### Changed: QRect(left, y, right - left + 1, my + 1);
+        // }
+//        if (!out_of_bounds)
+//            qDebug("consumer->changed(QRect(%d, %d, %d, %d))", left, y, right-left+1, my+1);
+        y+=8;
+        if (y>bottom) {
+            interlace++; y=top+4;
+            if (y > bottom) { // for really broken GIFs with bottom < 5
+                interlace=2;
+                y = top + 2;
+                if (y > bottom) { // for really broken GIF with bottom < 3
+                    interlace = 0;
+                    y = top + 1;
+                }
+            }
+        }
+    } break;
+    case 2: {
+        int i;
+        my = qMin(3, bottom-y);
+        // Don't dup with transparency
+        if (trans_index < 0) {
+            for (i=1; i<=my; i++) {
+                memcpy(image->scanLine(y+i)+left*sizeof(QRgb), image->scanLine(y)+left*sizeof(QRgb),
+                       (right-left+1)*sizeof(QRgb));
+            }
+        }
+
+        // if (!out_of_bounds) {
+        //     ### Changed: QRect(left, y, right - left + 1, my + 1);
+        // }
+        y+=8;
+        if (y>bottom) {
+            interlace++; y=top+2;
+            // handle broken GIF with bottom < 3
+            if (y > bottom) {
+                interlace = 3;
+                y = top + 1;
+            }
+        }
+    } break;
+    case 3: {
+        int i;
+        my = qMin(1, bottom-y);
+        // Don't dup with transparency
+        if (trans_index < 0) {
+            for (i=1; i<=my; i++) {
+                memcpy(image->scanLine(y+i)+left*sizeof(QRgb), image->scanLine(y)+left*sizeof(QRgb),
+                       (right-left+1)*sizeof(QRgb));
+            }
+        }
+        // if (!out_of_bounds) {
+        //     ### Changed: QRect(left, y, right - left + 1, my + 1);
+        // }
+        y+=4;
+        if (y>bottom) { interlace++; y=top+1; }
+    } break;
+    case 4:
+        // if (!out_of_bounds) {
+        //     ### Changed: QRect(left, y, right - left + 1, 1);
+        // }
+        y+=2;
+    }
+
+    // Consume bogus extra lines
+    if (y >= sheight) out_of_bounds=true; //y=bottom;
+}
+
+inline QRgb QGIFFormat::color(uchar index) const
+{
+    if (index == trans_index || index > ncols)
+        return Q_TRANSPARENT;
+
+    QRgb *map = lcmap ? localcmap : globalcmap;
+    return map ? map[index] : 0;
+}
+
+//-------------------------------------------------------------------------
+//-------------------------------------------------------------------------
+//-------------------------------------------------------------------------
+
+QGifHandler::QGifHandler()
+{
+    gifFormat = new QGIFFormat;
+    nextDelay = 0;
+    loopCnt = 0;
+    frameNumber = -1;
+    nextSize = QSize();
+}
+
+QGifHandler::~QGifHandler()
+{
+    delete gifFormat;
+}
+
+// Does partial decode if necessary, just to see if an image is coming
+
+bool QGifHandler::imageIsComing() const
+{
+    const int GifChunkSize = 4096;
+
+    while (!gifFormat->partialNewFrame) {
+        if (buffer.isEmpty()) {
+            buffer += device()->read(GifChunkSize);
+            if (buffer.isEmpty())
+                break;
+        }
+
+        int decoded = gifFormat->decode(&lastImage, (const uchar *)buffer.constData(), buffer.size(),
+                                        &nextDelay, &loopCnt, &nextSize);
+        if (decoded == -1)
+            break;
+        buffer.remove(0, decoded);
+    }
+    return gifFormat->partialNewFrame;
+}
+
+bool QGifHandler::canRead() const
+{
+    if (!nextDelay && canRead(device())) {
+        setFormat("gif");
+        return true;
+    }
+
+    return imageIsComing();
+}
+
+bool QGifHandler::canRead(QIODevice *device)
+{
+    if (!device) {
+        qWarning("QGifHandler::canRead() called with no device");
+        return false;
+    }
+
+    char head[6];
+    if (device->peek(head, sizeof(head)) == sizeof(head))
+        return qstrncmp(head, "GIF87a", 6) == 0
+            || qstrncmp(head, "GIF89a", 6) == 0;
+    return false;
+}
+
+bool QGifHandler::read(QImage *image)
+{
+    const int GifChunkSize = 4096;
+
+    while (!gifFormat->newFrame) {
+        if (buffer.isEmpty()) {
+            buffer += device()->read(GifChunkSize);
+            if (buffer.isEmpty())
+                break;
+        }
+
+        int decoded = gifFormat->decode(&lastImage, (const uchar *)buffer.constData(), buffer.size(),
+                                        &nextDelay, &loopCnt, &nextSize);
+        if (decoded == -1)
+            break;
+        buffer.remove(0, decoded);
+    }
+    if (gifFormat->newFrame || (gifFormat->partialNewFrame && device()->atEnd())) {
+        *image = lastImage;
+        ++frameNumber;
+        gifFormat->newFrame = false;
+        gifFormat->partialNewFrame = false;
+        return true;
+    }
+
+    return false;
+}
+
+bool QGifHandler::write(const QImage &image)
+{
+    Q_UNUSED(image);
+    return false;
+}
+
+bool QGifHandler::supportsOption(ImageOption option) const
+{
+    return option == Size
+        || option == Animation;
+}
+
+QVariant QGifHandler::option(ImageOption option) const
+{
+    if (option == Size) {
+        if (imageIsComing())
+            return nextSize;
+    } else if (option == Animation) {
+        return true;
+    }
+    return QVariant();
+}
+
+void QGifHandler::setOption(ImageOption option, const QVariant &value)
+{
+    Q_UNUSED(option);
+    Q_UNUSED(value);
+}
+
+int QGifHandler::nextImageDelay() const
+{
+    return nextDelay;
+}
+
+int QGifHandler::imageCount() const
+{
+    return 0; // Don't know
+}
+
+int QGifHandler::loopCount() const
+{
+    return loopCnt-1; // In GIF, loop count is iteration count, so subtract one
+}
+
+int QGifHandler::currentImageNumber() const
+{
+    return frameNumber;
+}
+
+QByteArray QGifHandler::name() const
+{
+    return "gif";
+}
+
+QT_END_NAMESPACE