qgifhandler.cpp

奇趣公司比较新的qt/emd版本

          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";
}