QGIFFormat Class Reference

Public Functions
int	decode (QImage *image, const uchar *buffer, int length, int *nextFrameDelay, int *loopCount)
	This function decodes some data into image changes. More...
	QGIFFormat ()
	Constructs a QGIFFormat. More...
	~QGIFFormat ()
	Destroys a QGIFFormat. More...

Static Public Functions
static void	scan (QIODevice *device, QVector< QSize > *imageSizes, int *loopCount)
	Scans through the data stream defined by device and returns the image sizes found in the stream in the imageSizes vector. More...

Public Variables
bool	newFrame
bool	partialNewFrame

Private Types
enum	{ max_lzw_bits =12 }
enum	Disposal { NoDisposal, DoNotChange, RestoreBackground, RestoreImage }
enum	State {   Header, LogicalScreenDescriptor, GlobalColorMap, LocalColorMap,   Introducer, ImageDescriptor, TableImageLZWSize, ImageDataBlockSize,   ImageDataBlock, ExtensionLabel, GraphicControlExtension, ApplicationExtension,   NetscapeExtensionBlockSize, NetscapeExtensionBlock, SkipBlockSize, SkipBlock,   Done, Error }

Private Functions
QRgb	color (uchar index) const
void	disposePrevious (QImage *image)
void	fillRect (QImage *image, int x, int y, int w, int h, QRgb col)
void	nextY (unsigned char *bits, int bpl)

Properties
int	accum
QImage	backingstore
int	bgcol
int	bitcount
int	bottom
int	ccount
int	clear_code
int	code_size
int	count
bool	digress
Disposal	disposal
bool	disposed
int	end_code
int	expectcount
int	firstcode
int	frame
bool	gcmap
bool	gif89
QRgb *	globalcmap
int	gncols
int	height
unsigned char	hold [16]
int	incode
int	interlace
bool	lcmap
int	left
int	lncols
QRgb *	localcmap
int	lzwsize
int	max_code
int	max_code_size
int	ncols
bool	needfirst
int	oldcode
bool	out_of_bounds
int	right
int	sheight
short *	sp
short *	stack
enum QGIFFormat::State	state
int	swidth
short *	table [2]
int	top
int	trans_index
int	width
int	x
int	y

Detailed Description

Definition at line 68 of file qgifhandler.cpp.

Enumerations

anonymous enum

anonymous enum

private

Enumerator
max_lzw_bits

Definition at line 131 of file qgifhandler.cpp.

{ max_lzw_bits=12 }; // (poor-compiler's static const int)

Disposal

enum QGIFFormat::Disposal

private

Enumerator
NoDisposal
DoNotChange
RestoreBackground
RestoreImage

Definition at line 121 of file qgifhandler.cpp.

{ NoDisposal, DoNotChange, RestoreBackground, RestoreImage };

State

enum QGIFFormat::State

private

Enumerator
Header
LogicalScreenDescriptor
GlobalColorMap
LocalColorMap
Introducer
ImageDescriptor
TableImageLZWSize
ImageDataBlockSize
ImageDataBlock
ExtensionLabel
GraphicControlExtension
ApplicationExtension
NetscapeExtensionBlockSize
NetscapeExtensionBlock
SkipBlockSize
SkipBlock
Done
Error

Definition at line 93 of file qgifhandler.cpp.

               {
        Header,
        LogicalScreenDescriptor,
        GlobalColorMap,
        LocalColorMap,
        Introducer,
        ImageDescriptor,
        TableImageLZWSize,
        ImageDataBlockSize,
        ImageDataBlock,
        ExtensionLabel,
        GraphicControlExtension,
        ApplicationExtension,
        NetscapeExtensionBlockSize,
        NetscapeExtensionBlock,
        SkipBlockSize,
        SkipBlock,
        Done,
        Error
    } state;

Constructors and Destructors

QGIFFormat()

QGIFFormat::QGIFFormat

(

)

Constructs a QGIFFormat.

Definition at line 150 of file qgifhandler.cpp.

Referenced by QGifHandler::QGifHandler().

{
    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;
    table[0] = 0;
    table[1] = 0;
    stack = 0;
}

~QGIFFormat()

QGIFFormat::~QGIFFormat

(

)

Destroys a QGIFFormat.

Definition at line 173 of file qgifhandler.cpp.

{
    if (globalcmap) delete[] globalcmap;
    if (localcmap) delete[] localcmap;
    delete [] stack;
}

Functions

color()

QRgb QGIFFormat::color ( uchar  index ) const

inlineprivate

Definition at line 1028 of file qgifhandler.cpp.

Referenced by decode(), disposePrevious(), and fillRect().

{
    if (index > ncols)
        return Q_TRANSPARENT;

    QRgb *map = lcmap ? localcmap : globalcmap;
    QRgb col = map ? map[index] : 0;
    return index == trans_index ? col & Q_TRANSPARENT : col;
}

decode()

int QGIFFormat::decode	(	QImage *	image,
		const uchar *	buffer,
		int	length,
		int *	nextFrameDelay,
		int *	loopCount
	)

This function decodes some data into image changes.

Returns the number of bytes consumed.

Definition at line 236 of file qgifhandler.cpp.

{
    // 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."

    if (!stack) {
        stack = new short[(1 << max_lzw_bits) * 4];
        table[0] = &stack[(1 << max_lzw_bits) * 2];
        table[1] = &stack[(1 << max_lzw_bits) * 3];
    }

    image->detach();
    int bpl = image->bytesPerLine();
    unsigned char *bits = image->bits();

#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);
                    bpl = image->bytesPerLine();
                    bits = image->bits();
                    memset(bits, 0, image->byteCount());
                }

                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(bits, 0, image->byteCount());
                    }
                    const int dest_bpl = backingstore.bytesPerLine();
                    unsigned char *dest_data = backingstore.bits();
                    for (int ln=0; ln<h; ln++) {
                        memcpy(FAST_SCAN_LINE(dest_data, dest_bpl, ln),
                               FAST_SCAN_LINE(bits, bpl, 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 && ((frame == 0) || (firstcode != trans_index)))
                            ((QRgb*)FAST_SCAN_LINE(bits, bpl, 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(bits, bpl);
                        }
                    } else {
                        incode=code;
                        if (code>=max_code) {
                            *sp++=firstcode;
                            code=oldcode;
                        }
                        while (code>=clear_code+2) {
                            if (code >= max_code) {
                                state = Error;
                                return -1;
                            }
                            *sp++=table[1][code];
                            if (code==table[0][code]) {
                                state=Error;
                                return -1;
                            }
                            if (sp-stack>=(1<<(max_lzw_bits))*2) {
                                state=Error;
                                return -1;
                            }
                            code=table[0][code];
                        }
                        if (code < 0) {
                            state = Error;
                            return -1;
                        }

                        *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();
                        QRgb *line = 0;
                        if (!out_of_bounds && h > y)
                            line = (QRgb*)FAST_SCAN_LINE(bits, bpl, y);
                        while (sp>stack) {
                            const uchar index = *(--sp);
                            if (!out_of_bounds && h > y && ((frame == 0) || (index != trans_index))) {
                                line[x] = color(index);
                            }
                            x++;
                            if (x>=swidth) out_of_bounds = true;
                            if (x>=left+width) {
                                x=left;
                                out_of_bounds = left>=swidth || y>=sheight;
                                nextY(bits, bpl);
                                if (!out_of_bounds && h > y)
                                    line = (QRgb*)FAST_SCAN_LINE(bits, bpl, 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;
}

disposePrevious()

void QGIFFormat::disposePrevious ( QImage *  image )

private

Definition at line 180 of file qgifhandler.cpp.

Referenced by decode().

{
    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;
}

fillRect()

void QGIFFormat::fillRect ( QImage *  image, int  x, int  y, int  w, int  h, QRgb  col  )

private

Definition at line 927 of file qgifhandler.cpp.

Referenced by decode(), and disposePrevious().

{
    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;
        }
    }
}

nextY()

void QGIFFormat::nextY ( unsigned char *  bits, int  bpl  )

private

Definition at line 938 of file qgifhandler.cpp.

Referenced by decode().

{
    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(FAST_SCAN_LINE(bits, bpl, y+i)+left*sizeof(QRgb), FAST_SCAN_LINE(bits, bpl, 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(FAST_SCAN_LINE(bits, bpl, y+i)+left*sizeof(QRgb), FAST_SCAN_LINE(bits, bpl, 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(FAST_SCAN_LINE(bits, bpl, y+i)+left*sizeof(QRgb), FAST_SCAN_LINE(bits, bpl, 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;
}

scan()

void QGIFFormat::scan ( QIODevice *  device, QVector< QSize > *  imageSizes, int *  loopCount  )

static

Scans through the data stream defined by device and returns the image sizes found in the stream in the imageSizes vector.

Definition at line 664 of file qgifhandler.cpp.

Referenced by QGifHandler::imageCount(), QGifHandler::loopCount(), and QGifHandler::option().

{
    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;
}

Properties

accum

int QGIFFormat::accum

private

Definition at line 128 of file qgifhandler.cpp.

Referenced by decode().

backingstore

QImage QGIFFormat::backingstore

private

Definition at line 87 of file qgifhandler.cpp.

Referenced by decode(), and disposePrevious().

bgcol

int QGIFFormat::bgcol

private

Definition at line 126 of file qgifhandler.cpp.

Referenced by decode(), and disposePrevious().

bitcount

int QGIFFormat::bitcount

private

Definition at line 129 of file qgifhandler.cpp.

Referenced by decode().

bottom

int QGIFFormat::bottom

private

Definition at line 120 of file qgifhandler.cpp.

Referenced by decode(), disposePrevious(), and nextY().

ccount

int QGIFFormat::ccount

private

Definition at line 91 of file qgifhandler.cpp.

Referenced by decode().

clear_code

int QGIFFormat::clear_code

private

Definition at line 133 of file qgifhandler.cpp.

Referenced by decode().

code_size

int QGIFFormat::code_size

private

Definition at line 133 of file qgifhandler.cpp.

Referenced by decode().

count

int QGIFFormat::count

private

Definition at line 90 of file qgifhandler.cpp.

Referenced by decode(), QGIFFormat(), and scan().

digress

bool QGIFFormat::digress

private

Definition at line 142 of file qgifhandler.cpp.

Referenced by decode().

disposal

Disposal QGIFFormat::disposal

private

Definition at line 122 of file qgifhandler.cpp.

Referenced by decode(), disposePrevious(), and QGIFFormat().

disposed

bool QGIFFormat::disposed

private

Definition at line 123 of file qgifhandler.cpp.

Referenced by decode(), disposePrevious(), and QGIFFormat().

end_code

int QGIFFormat::end_code

private

Definition at line 133 of file qgifhandler.cpp.

Referenced by decode().

expectcount

int QGIFFormat::expectcount

private

Definition at line 92 of file qgifhandler.cpp.

Referenced by decode().

firstcode

int QGIFFormat::firstcode

private

Definition at line 134 of file qgifhandler.cpp.

Referenced by decode().

frame

int QGIFFormat::frame

private

Definition at line 140 of file qgifhandler.cpp.

Referenced by decode(), disposePrevious(), and QGIFFormat().

gcmap

bool QGIFFormat::gcmap

private

Definition at line 125 of file qgifhandler.cpp.

Referenced by decode().

gif89

bool QGIFFormat::gif89

private

Definition at line 89 of file qgifhandler.cpp.

Referenced by decode().

globalcmap

QRgb* QGIFFormat::globalcmap

private

Definition at line 85 of file qgifhandler.cpp.

Referenced by color(), decode(), QGIFFormat(), and ~QGIFFormat().

gncols

int QGIFFormat::gncols

private

Definition at line 113 of file qgifhandler.cpp.

Referenced by decode(), and QGIFFormat().

height

int QGIFFormat::height

private

Definition at line 119 of file qgifhandler.cpp.

Referenced by decode().

hold

unsigned char QGIFFormat::hold[16]

private

Definition at line 88 of file qgifhandler.cpp.

Referenced by decode(), and scan().

incode

int QGIFFormat::incode

private

Definition at line 134 of file qgifhandler.cpp.

Referenced by decode().

interlace

int QGIFFormat::interlace

private

Definition at line 127 of file qgifhandler.cpp.

Referenced by decode(), and nextY().

lcmap

bool QGIFFormat::lcmap

private

Definition at line 117 of file qgifhandler.cpp.

Referenced by color(), decode(), and QGIFFormat().

left

int QGIFFormat::left

private

Definition at line 120 of file qgifhandler.cpp.

Referenced by decode(), disposePrevious(), and nextY().

lncols

int QGIFFormat::lncols

private

Definition at line 114 of file qgifhandler.cpp.

Referenced by decode(), and QGIFFormat().

localcmap

QRgb* QGIFFormat::localcmap

private

Definition at line 86 of file qgifhandler.cpp.

Referenced by color(), decode(), QGIFFormat(), and ~QGIFFormat().

lzwsize

int QGIFFormat::lzwsize

private

Definition at line 116 of file qgifhandler.cpp.

Referenced by decode().

max_code

int QGIFFormat::max_code

private

Definition at line 133 of file qgifhandler.cpp.

Referenced by decode().

max_code_size

int QGIFFormat::max_code_size

private

Definition at line 133 of file qgifhandler.cpp.

Referenced by decode().

ncols

int QGIFFormat::ncols

private

Definition at line 115 of file qgifhandler.cpp.

Referenced by color(), and decode().

needfirst

bool QGIFFormat::needfirst

private

Definition at line 138 of file qgifhandler.cpp.

Referenced by decode().

newFrame

bool QGIFFormat::newFrame

Definition at line 77 of file qgifhandler.cpp.

Referenced by decode(), and QGIFFormat().

oldcode

int QGIFFormat::oldcode

private

Definition at line 134 of file qgifhandler.cpp.

Referenced by decode().

out_of_bounds

bool QGIFFormat::out_of_bounds

private

Definition at line 141 of file qgifhandler.cpp.

Referenced by decode(), disposePrevious(), nextY(), and QGIFFormat().

partialNewFrame

bool QGIFFormat::partialNewFrame

Definition at line 78 of file qgifhandler.cpp.

Referenced by decode(), and QGIFFormat().

right

int QGIFFormat::right

private

Definition at line 120 of file qgifhandler.cpp.

Referenced by decode(), disposePrevious(), and nextY().

sheight

int QGIFFormat::sheight

private

Definition at line 118 of file qgifhandler.cpp.

Referenced by decode(), disposePrevious(), and nextY().

sp

short* QGIFFormat::sp

private

Definition at line 137 of file qgifhandler.cpp.

Referenced by decode().

stack

short* QGIFFormat::stack

private

Definition at line 136 of file qgifhandler.cpp.

Referenced by decode(), QGIFFormat(), and ~QGIFFormat().

state

enum QGIFFormat::State QGIFFormat::state

private

Referenced by decode(), QGIFFormat(), and scan().

swidth

int QGIFFormat::swidth

private

Definition at line 118 of file qgifhandler.cpp.

Referenced by decode(), and disposePrevious().

table

short* QGIFFormat::table[2]

private

Definition at line 135 of file qgifhandler.cpp.

Referenced by decode(), and QGIFFormat().

top

int QGIFFormat::top

private

Definition at line 120 of file qgifhandler.cpp.

Referenced by decode(), disposePrevious(), and nextY().

trans_index

int QGIFFormat::trans_index

private

Definition at line 124 of file qgifhandler.cpp.

Referenced by color(), decode(), disposePrevious(), and nextY().

width

int QGIFFormat::width

private

Definition at line 119 of file qgifhandler.cpp.

Referenced by decode().

x

int QGIFFormat::x

private

Definition at line 139 of file qgifhandler.cpp.

Referenced by decode().

y

int QGIFFormat::y

private

Definition at line 139 of file qgifhandler.cpp.

Referenced by decode(), and nextY().

---

The documentation for this class was generated from the following file:

• /src/gui/image/qgifhandler.cpp