// Copyright (C) 2016 The Qt Company Ltd.

// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only

// Qt-Security score:critical reason:data-parser

#include "private/qbmphandler_p.h"

#ifndef QT_NO_IMAGEFORMAT_BMP

#include <qimage.h>

#include <qlist.h>

#include <qvariant.h>

QT_BEGIN_NAMESPACE

static void swapPixel01(QImage *image)        // 1-bpp: swap 0 and 1 pixels

{

    qsizetype i;

    if (image->depth() == 1 && image->colorCount() == 2) {

        uint *p = (uint *)image->bits();

        qsizetype nbytes = static_cast<qsizetype>(image->sizeInBytes());

        for (i=0; i<nbytes/4; i++) {

            *p = ~*p;

            p++;

        }

        uchar *p2 = (uchar *)p;

        for (i=0; i<(nbytes&3); i++) {

            *p2 = ~*p2;

            p2++;

        }

        QRgb t = image->color(0);                // swap color 0 and 1

        image->setColor(0, image->color(1));

        image->setColor(1, t);

    }

}

/*

    QImageIO::defineIOHandler("BMP", "^BM", 0,

                               read_bmp_image, write_bmp_image);

*/

/*****************************************************************************

  BMP (DIB) image read/write functions

 *****************************************************************************/

const int BMP_FILEHDR_SIZE = 14;                // size of BMP_FILEHDR data

static QDataStream &operator>>(QDataStream &s, BMP_FILEHDR &bf)

{                                                // read file header

    s.readRawData(bf.bfType, 2);

    s >> bf.bfSize >> bf.bfReserved1 >> bf.bfReserved2 >> bf.bfOffBits;

    return s;

}

static QDataStream &operator<<(QDataStream &s, const BMP_FILEHDR &bf)

{                                                // write file header

    s.writeRawData(bf.bfType, 2);

    s << bf.bfSize << bf.bfReserved1 << bf.bfReserved2 << bf.bfOffBits;

    return s;

}

const int BMP_OLD  = 12;                        // old Windows/OS2 BMP size

const int BMP_WIN  = 40;                        // Windows BMP v3 size

const int BMP_OS2  = 64;                        // new OS/2 BMP size

const int BMP_WIN4 = 108;                       // Windows BMP v4 size

const int BMP_WIN5 = 124;                       // Windows BMP v5 size

const int BMP_RGB  = 0;                                // no compression

const int BMP_RLE8 = 1;                                // run-length encoded, 8 bits

const int BMP_RLE4 = 2;                                // run-length encoded, 4 bits

const int BMP_BITFIELDS = 3;                        // RGB values encoded in data as bit-fields

const int BMP_ALPHABITFIELDS = 4;                   // RGBA values encoded in data as bit-fields

static QDataStream &operator>>(QDataStream &s, BMP_INFOHDR &bi)

{

    s >> bi.biSize;

    if (bi.biSize == BMP_WIN || bi.biSize == BMP_OS2 || bi.biSize == BMP_WIN4 || bi.biSize == BMP_WIN5) {

        s >> bi.biWidth >> bi.biHeight >> bi.biPlanes >> bi.biBitCount;

        s >> bi.biCompression >> bi.biSizeImage;

        s >> bi.biXPelsPerMeter >> bi.biYPelsPerMeter;

        s >> bi.biClrUsed >> bi.biClrImportant;

        if (bi.biSize >= BMP_WIN4) {

            s >> bi.biRedMask >> bi.biGreenMask >> bi.biBlueMask >> bi.biAlphaMask;

            s >> bi.biCSType;

            for (int i = 0; i < 9; ++i)

                s >> bi.biEndpoints[i];

            s >> bi.biGammaRed >> bi.biGammaGreen >> bi.biGammaBlue;

            if (bi.biSize == BMP_WIN5)

                s >> bi.biIntent >> bi.biProfileData >> bi.biProfileSize >> bi.biReserved;

        }

    }

    else {                                        // probably old Windows format

        qint16 w, h;

        s >> w >> h >> bi.biPlanes >> bi.biBitCount;

        bi.biWidth  = w;

        bi.biHeight = h;

        bi.biCompression = BMP_RGB;                // no compression

        bi.biSizeImage = 0;

        bi.biXPelsPerMeter = bi.biYPelsPerMeter = 0;

        bi.biClrUsed = bi.biClrImportant = 0;

    }

    return s;

}

static QDataStream &operator<<(QDataStream &s, const BMP_INFOHDR &bi)

{

    s << bi.biSize;

    s << bi.biWidth << bi.biHeight;

    s << bi.biPlanes;

    s << bi.biBitCount;

    s << bi.biCompression;

    s << bi.biSizeImage;

    s << bi.biXPelsPerMeter << bi.biYPelsPerMeter;

    s << bi.biClrUsed << bi.biClrImportant;

    if (bi.biSize >= BMP_WIN4) {

        s << bi.biRedMask << bi.biGreenMask << bi.biBlueMask << bi.biAlphaMask;

        s << bi.biCSType;

        for (int i = 0; i < 9; i++)

            s << bi.biEndpoints[i];

        s << bi.biGammaRed;

        s << bi.biGammaGreen;

        s << bi.biGammaBlue;

    }

    if (bi.biSize >= BMP_WIN5) {

        s << bi.biIntent;

        s << bi.biProfileData;

        s << bi.biProfileSize;

        s << bi.biReserved;

    }

    return s;

}

static uint calc_shift(uint mask)

{

    uint result = 0;

    while ((mask >= 0x100) || (!(mask & 1) && mask)) {

        result++;

        mask >>= 1;

    }

    return result;

}

static uint calc_scale(uint low_mask)

{

    uint result = 8;

    while (low_mask && result) {

        result--;

        low_mask >>= 1;

    }

    return result;

}

static inline uint apply_scale(uint value, uint scale)

{

    if (!(scale & 0x07)) // return immediately if scale == 8 or 0

        return value;

    uint filled = 8 - scale;

    uint result = value << scale;

    do {

        result |= result >> filled;

        filled <<= 1;

    } while (filled < 8);

    return result;

}

static bool read_dib_fileheader(QDataStream &s, BMP_FILEHDR &bf)

{

    // read BMP file header

    if (!(s >> bf))

        return false;

    // check header

    if (qstrncmp(bf.bfType,"BM",2) != 0)

        return false;

    return true;

}

static bool read_dib_infoheader(QDataStream &s, BMP_INFOHDR &bi)

{

    if (!(s >> bi))                                       // read BMP info header

        return false;

    int nbits = bi.biBitCount;

    int comp = bi.biCompression;

    if (!(nbits == 1 || nbits == 4 || nbits == 8 || nbits == 16 || nbits == 24 || nbits == 32) ||

        bi.biPlanes != 1 || comp > BMP_BITFIELDS)

        return false;                                        // weird BMP image

    if (!(comp == BMP_RGB || (nbits == 4 && comp == BMP_RLE4) ||

        (nbits == 8 && comp == BMP_RLE8) || ((nbits == 16 || nbits == 32) && comp == BMP_BITFIELDS)))

         return false;                                // weird compression type

    if (bi.biHeight == INT_MIN)

        return false; // out of range for positive int

    if (bi.biWidth <= 0 || !bi.biHeight || quint64(bi.biWidth) * qAbs(bi.biHeight) > 16384 * 16384)

        return false;

    return true;

}

static bool read_dib_body(QDataStream &s, const BMP_INFOHDR &bi, qint64 datapos, qint64 startpos, QImage &image)

{

    QIODevice* d = s.device();

    if (d->atEnd())                                // end of stream/file

        return false;

#if 0

    qDebug("offset...........%lld", datapos);

    qDebug("startpos.........%lld", startpos);

    qDebug("biSize...........%d", bi.biSize);

    qDebug("biWidth..........%d", bi.biWidth);

    qDebug("biHeight.........%d", bi.biHeight);

    qDebug("biPlanes.........%d", bi.biPlanes);

    qDebug("biBitCount.......%d", bi.biBitCount);

    qDebug("biCompression....%d", bi.biCompression);

    qDebug("biSizeImage......%d", bi.biSizeImage);

    qDebug("biXPelsPerMeter..%d", bi.biXPelsPerMeter);

    qDebug("biYPelsPerMeter..%d", bi.biYPelsPerMeter);

    qDebug("biClrUsed........%d", bi.biClrUsed);

    qDebug("biClrImportant...%d", bi.biClrImportant);

#endif

    int w = bi.biWidth,         h = bi.biHeight,  nbits = bi.biBitCount;

    int t = bi.biSize,         comp = bi.biCompression;

    uint red_mask = 0;

    uint green_mask = 0;

    uint blue_mask = 0;

    uint alpha_mask = 0;

    uint red_shift = 0;

    uint green_shift = 0;

    uint blue_shift = 0;

    uint alpha_shift = 0;

    uint red_scale = 0;

    uint green_scale = 0;

    uint blue_scale = 0;

    uint alpha_scale = 0;

    bool bitfields = comp == BMP_BITFIELDS || comp == BMP_ALPHABITFIELDS;

    if (!d->isSequential())

        d->seek(startpos + bi.biSize); // goto start of colormap or masks

    if (bi.biSize >= BMP_WIN4) {

        red_mask = bi.biRedMask;

        green_mask = bi.biGreenMask;

        blue_mask = bi.biBlueMask;

        alpha_mask = bi.biAlphaMask;

    } else if (bitfields && (nbits == 16 || nbits == 32)) {

        if (d->read((char *)&red_mask, sizeof(red_mask)) != sizeof(red_mask))

            return false;

        if (d->read((char *)&green_mask, sizeof(green_mask)) != sizeof(green_mask))

            return false;

        if (d->read((char *)&blue_mask, sizeof(blue_mask)) != sizeof(blue_mask))

            return false;

        if (comp == BMP_ALPHABITFIELDS && d->read((char *)&alpha_mask, sizeof(alpha_mask)) != sizeof(alpha_mask))

            return false;

    }

    bool transp = bitfields || (comp == BMP_RGB && nbits == 32 && alpha_mask == 0xff000000);

    transp = transp && alpha_mask;

    int ncols = 0;

    int depth = 0;

    QImage::Format format;

    switch (nbits) {

        case 32:

        case 24:

        case 16:

            depth = 32;

            format = transp ? QImage::Format_ARGB32 : QImage::Format_RGB32;

            break;

        case 8:

        case 4:

            depth = 8;

            format = QImage::Format_Indexed8;

            break;

        case 1:

            depth = 1;

            format = QImage::Format_Mono;

            break;

        default:

            return false;

            break;

    }

    if (depth != 32) {

        ncols = bi.biClrUsed ? bi.biClrUsed : 1 << nbits;

        if (ncols < 1 || ncols > 256) // sanity check - don't run out of mem if color table is broken

            return false;

    }

    if (bi.biHeight < 0)

        h = -h;                  // support images with negative height

    if (!QImageIOHandler::allocateImage(QSize(w, h), format, &image))

        return false;

    image.fill(0);

    if (ncols > 0) {                                // read color table

        image.setColorCount(ncols);

        uchar rgb[4];

        int   rgb_len = t == BMP_OLD ? 3 : 4;

        for (int i=0; i<ncols; i++) {

            if (d->read((char *)rgb, rgb_len) != rgb_len)

                return false;

            image.setColor(i, qRgb(rgb[2],rgb[1],rgb[0]));

            if (d->atEnd())                        // truncated file

                return false;

        }

    } else if (bitfields && (nbits == 16 || nbits == 32)) {

        red_shift = calc_shift(red_mask);

        if (((red_mask >> red_shift) + 1) == 0)

            return false;

        red_scale = calc_scale(red_mask >> red_shift);

        green_shift = calc_shift(green_mask);

        if (((green_mask >> green_shift) + 1) == 0)

            return false;

        green_scale = calc_scale(green_mask >> green_shift);

        blue_shift = calc_shift(blue_mask);

        if (((blue_mask >> blue_shift) + 1) == 0)

            return false;

        blue_scale = calc_scale(blue_mask >> blue_shift);

        alpha_shift = calc_shift(alpha_mask);

        if (((alpha_mask >> alpha_shift) + 1) == 0)

            return false;

        alpha_scale = calc_scale(alpha_mask >> alpha_shift);

    } else if (comp == BMP_RGB && (nbits == 24 || nbits == 32)) {

        blue_mask = 0x000000ff;

        green_mask = 0x0000ff00;

        red_mask = 0x00ff0000;

        blue_shift = 0;

        green_shift = 8;

        red_shift = 16;

        blue_scale = green_scale = red_scale = 0;

        if (transp) {

            alpha_shift = calc_shift(alpha_mask);

            if (((alpha_mask >> alpha_shift) + 1) == 0)

                return false;

            alpha_scale = calc_scale(alpha_mask >> alpha_shift);

        }

    } else if (comp == BMP_RGB && nbits == 16) {

        blue_mask = 0x001f;

        green_mask = 0x03e0;

        red_mask = 0x7c00;

        blue_shift = 0;

        green_shift = 5;

        red_shift = 10;

        blue_scale = green_scale = red_scale = 3;

    }

    image.setDotsPerMeterX(bi.biXPelsPerMeter);

    image.setDotsPerMeterY(bi.biYPelsPerMeter);

#if 0

    qDebug("Rmask: %08x Rshift: %08x Rscale:%08x", red_mask, red_shift, red_scale);

    qDebug("Gmask: %08x Gshift: %08x Gscale:%08x", green_mask, green_shift, green_scale);

    qDebug("Bmask: %08x Bshift: %08x Bscale:%08x", blue_mask, blue_shift, blue_scale);

    qDebug("Amask: %08x Ashift: %08x Ascale:%08x", alpha_mask, alpha_shift, alpha_scale);

#endif

    if (datapos >= 0 && datapos > d->pos()) {

        if (!d->isSequential())

            d->seek(datapos); // start of image data

    }

    int             bpl = image.bytesPerLine();

    uchar *data = image.bits();

    if (nbits == 1) {                                // 1 bit BMP image

        while (--h >= 0) {

            if (d->read((char*)(data + h*bpl), bpl) != bpl)

                break;

        }

        if (ncols == 2 && qGray(image.color(0)) < qGray(image.color(1)))

            swapPixel01(&image);                // pixel 0 is white!

    }

    else if (nbits == 4) {                        // 4 bit BMP image

        int    buflen = ((w+7)/8)*4;

        uchar *buf    = new uchar[buflen];

        if (comp == BMP_RLE4) {                // run length compression

            int x=0, y=0, c, i;

            quint8 b;

            uchar *p = data + (h-1)*bpl;

            const uchar *endp = p + w;

            while (y < h) {

                if (!d->getChar((char *)&b))

                    break;

                if (b == 0) {                        // escape code

                    if (!d->getChar((char *)&b) || b == 1) {

                        y = h;                // exit loop

                    } else switch (b) {

                        case 0:                        // end of line

                            x = 0;

                            y++;

                            p = data + (h-y-1)*bpl;

                            break;

                        case 2:                        // delta (jump)

                        {

                            quint8 tmp = 0;

                            d->getChar((char *)&tmp);

                            x += tmp;

                            d->getChar((char *)&tmp);

                            y += tmp;

                        }

                            // Protection

                            if ((uint)x >= (uint)w)

                                x = w-1;

                            if ((uint)y >= (uint)h)

                                y = h-1;

                            p = data + (h-y-1)*bpl + x;

                            break;

                        default:                // absolute mode

                            // Protection

                            if (p + b > endp)

                                b = endp-p;

                            i = (c = b)/2;

                            while (i--) {

                                d->getChar((char *)&b);

                                *p++ = b >> 4;

                                *p++ = b & 0x0f;

                            }

                            if (c & 1) {

                                unsigned char tmp = 0;

                                d->getChar((char *)&tmp);

                                *p++ = tmp >> 4;

                            }

                            if ((((c & 3) + 1) & 2) == 2)

                                d->getChar(nullptr);        // align on word boundary

                            x += c;

                    }

                } else {                        // encoded mode

                    // Protection

                    if (p + b > endp)

                        b = endp-p;

                    i = (c = b)/2;

                    d->getChar((char *)&b);                // 2 pixels to be repeated

                    while (i--) {

                        *p++ = b >> 4;

                        *p++ = b & 0x0f;

                    }

                    if (c & 1)

                        *p++ = b >> 4;

                    x += c;

                }

            }

        } else if (comp == BMP_RGB) {                // no compression

            while (--h >= 0) {

                if (d->read((char*)buf,buflen) != buflen)

                    break;

                uchar *p = data + h*bpl;

                uchar *b = buf;

                for (int i=0; i<w/2; i++) {        // convert nibbles to bytes

                    *p++ = *b >> 4;

                    *p++ = *b++ & 0x0f;

                }

                if (w & 1)                        // the last nibble

                    *p = *b >> 4;

            }

        }

        delete [] buf;

    }

    else if (nbits == 8) {                        // 8 bit BMP image

        if (comp == BMP_RLE8) {                // run length compression

            int x=0, y=0;

            quint8 b;

            uchar *p = data + (h-1)*bpl;

            const uchar *endp = p + w;

            while (y < h) {

                if (!d->getChar((char *)&b))

                    break;

                if (b == 0) {                        // escape code

                    if (!d->getChar((char *)&b) || b == 1) {

                            y = h;                // exit loop

                    } else switch (b) {

                        case 0:                        // end of line

                            x = 0;

                            y++;

                            p = data + (h-y-1)*bpl;

                            break;

                        case 2:                        // delta (jump)

                            {

                                quint8 tmp = 0;

                                d->getChar((char *)&tmp);

                                x += tmp;

                                d->getChar((char *)&tmp);

                                y += tmp;

                            }

                            // Protection

                            if ((uint)x >= (uint)w)

                                x = w-1;

                            if ((uint)y >= (uint)h)

                                y = h-1;

                            p = data + (h-y-1)*bpl + x;

                            break;

                        default:                // absolute mode

                            // Protection

                            if (p + b > endp)

                                b = endp-p;

                            if (d->read((char *)p, b) != b)

                                return false;

                            if ((b & 1) == 1)

                                d->getChar(nullptr);        // align on word boundary

                            x += b;

                            p += b;

                    }

                } else {                        // encoded mode

                    // Protection

                    if (p + b > endp)

                        b = endp-p;

                    char tmp = 0;

                    d->getChar(&tmp);

                    memset(p, tmp, b); // repeat pixel

                    x += b;

                    p += b;

                }

            }

        } else if (comp == BMP_RGB) {                // uncompressed

            while (--h >= 0) {

                if (d->read((char *)data + h*bpl, bpl) != bpl)

                    break;

            }

        }

    }

    else if (nbits == 16 || nbits == 24 || nbits == 32) { // 16,24,32 bit BMP image

        QRgb *p;

        QRgb  *end;

        uchar *buf24 = new uchar[bpl];

        qint64 bpl24 = ((qint64(w)*nbits+31)/32)*4;

        uchar *b;

        int c;

        while (--h >= 0) {

            p = (QRgb *)(data + h*bpl);

            end = p + w;

            if (d->read((char *)buf24,bpl24) != bpl24)

                break;

            b = buf24;

            while (p < end) {

                c = *(uchar*)b | (*(uchar*)(b+1)<<8);

                if (nbits > 16)

                    c |= *(uchar*)(b+2)<<16;

                if (nbits > 24)

                    c |= *(uchar*)(b+3)<<24;

                *p++ = qRgba(apply_scale((c & red_mask) >> red_shift, red_scale),

                             apply_scale((c & green_mask) >> green_shift, green_scale),

                             apply_scale((c & blue_mask) >> blue_shift, blue_scale),

                             transp ? apply_scale((c & alpha_mask) >> alpha_shift, alpha_scale) : 0xff);

                b += nbits/8;

            }

        }

        delete[] buf24;

    }

    if (bi.biHeight < 0) {

        // Flip the image

        uchar *buf = new uchar[bpl];

        h = -bi.biHeight;

        for (int y = 0; y < h/2; ++y) {

            memcpy(buf, data + y*bpl, bpl);

            memcpy(data + y*bpl, data + (h-y-1)*bpl, bpl);

            memcpy(data + (h-y-1)*bpl, buf, bpl);

        }

        delete [] buf;

    }

    return true;

}

bool qt_write_dib(QDataStream &s, const QImage &image, int bpl, int bpl_bmp, int nbits)

{

    QIODevice* d = s.device();

    if (!d->isWritable())

        return false;

    BMP_INFOHDR bi = { };

    bi.biSize               = BMP_WIN;                // build info header

    bi.biWidth               = image.width();

    bi.biHeight               = image.height();

    bi.biPlanes               = 1;

    bi.biBitCount      = nbits;

    bi.biCompression   = BMP_RGB;

    bi.biSizeImage     = bpl_bmp*image.height();

    bi.biXPelsPerMeter = image.dotsPerMeterX() ? image.dotsPerMeterX()

                                                : 2834; // 72 dpi default

    bi.biYPelsPerMeter = image.dotsPerMeterY() ? image.dotsPerMeterY() : 2834;

    bi.biClrUsed       = image.colorCount();

    bi.biClrImportant  = image.colorCount();

    if (!(s << bi))                                        // write info header

        return false;

    if (image.depth() != 32) {                // write color table

        uchar *color_table = new uchar[4*image.colorCount()];

        uchar *rgb = color_table;

        const QList<QRgb> c = image.colorTable();

        for (int i = 0; i < image.colorCount(); i++) {

            *rgb++ = qBlue (c[i]);

            *rgb++ = qGreen(c[i]);

            *rgb++ = qRed  (c[i]);

            *rgb++ = 0;

        }

        if (d->write((char *)color_table, 4*image.colorCount()) == -1) {

            delete [] color_table;

            return false;

        }

        delete [] color_table;

    }

    int y;

    if (nbits == 1 || nbits == 8) {                // direct output

        for (y=image.height()-1; y>=0; y--) {

            if (d->write((const char*)image.constScanLine(y), bpl) == -1)

                return false;

        }

        return true;

    }

    uchar *buf        = new uchar[bpl_bmp];

    uchar *b, *end;

    const uchar *p;

    memset(buf, 0, bpl_bmp);

    for (y=image.height()-1; y>=0; y--) {        // write the image bits

        if (nbits == 4) {                        // convert 8 -> 4 bits

            p = image.constScanLine(y);

            b = buf;

            end = b + image.width()/2;

            while (b < end) {

                *b++ = (*p << 4) | (*(p+1) & 0x0f);

                p += 2;

            }

            if (image.width() & 1)

                *b = *p << 4;

        } else {                                // 32 bits

            const QRgb *p   = (const QRgb *)image.constScanLine(y);

            const QRgb *end = p + image.width();

            b = buf;

            while (p < end) {

                *b++ = qBlue(*p);

                *b++ = qGreen(*p);

                *b++ = qRed(*p);

                p++;

            }

        }

        if (bpl_bmp != d->write((char*)buf, bpl_bmp)) {

            delete[] buf;

            return false;

        }

    }

    delete[] buf;

    return true;

}

QBmpHandler::QBmpHandler(InternalFormat fmt) :

    m_format(fmt), state(Ready)

{

}

QByteArray QBmpHandler::formatName() const

{

    return m_format == BmpFormat ? "bmp" : "dib";

}

bool QBmpHandler::readHeader()

{

    state = Error;

    QIODevice *d = device();

    QDataStream s(d);

    startpos = d->pos();

    // Intel byte order

    s.setByteOrder(QDataStream::LittleEndian);

    // read BMP file header

    if (m_format == BmpFormat && !read_dib_fileheader(s, fileHeader))

        return false;

    // read BMP info header

    if (!read_dib_infoheader(s, infoHeader))

        return false;

    state = ReadHeader;

    return true;

}

bool QBmpHandler::canRead() const

{

    if (m_format == BmpFormat && state == Ready && !canRead(device()))

        return false;

    if (state != Error) {

        setFormat(formatName());

        return true;

    }

    return false;

}

bool QBmpHandler::canRead(QIODevice *device)

{

    if (!device) {

        qWarning("QBmpHandler::canRead() called with 0 pointer");

        return false;

    }

    char head[2];

    if (device->peek(head, sizeof(head)) != sizeof(head))

        return false;

    return (qstrncmp(head, "BM", 2) == 0);

}

bool QBmpHandler::read(QImage *image)

{

    if (state == Error)

        return false;

    if (!image) {

        qWarning("QBmpHandler::read: cannot read into null pointer");

        return false;

    }

    if (state == Ready && !readHeader()) {

        state = Error;

        return false;

    }

    QIODevice *d = device();

    QDataStream s(d);

    // Intel byte order

    s.setByteOrder(QDataStream::LittleEndian);

    // read image

    qint64 datapos = startpos;

    if (m_format == BmpFormat) {

        datapos += fileHeader.bfOffBits;

    } else {

        // QTBUG-100351: We have no file header when reading dib format so we have to depend on the size of the

        // buffer and the biSizeImage value to find where the pixel data starts since there's sometimes optional

        // color mask values after biSize, like for example when pasting from the windows snipping tool.

        if (infoHeader.biSizeImage > 0 && infoHeader.biSizeImage < d->size()) {

            datapos = d->size() - infoHeader.biSizeImage;

        } else {

            // And sometimes biSizeImage is not filled in like when pasting from Microsoft Edge, so then we just

            // have to assume the optional color mask values are there.

            datapos += infoHeader.biSize;

            if (infoHeader.biBitCount == 16 || infoHeader.biBitCount == 32) {

                if (infoHeader.biCompression == BMP_BITFIELDS) {

                    datapos += 12;

                } else if (infoHeader.biCompression == BMP_ALPHABITFIELDS) {

                    datapos += 16;

                }

            }

        }

    }

    const bool readSuccess = m_format == BmpFormat ?

        read_dib_body(s, infoHeader, datapos, startpos + BMP_FILEHDR_SIZE, *image) :

        read_dib_body(s, infoHeader, datapos, startpos, *image);

    if (!readSuccess)

        return false;

    state = Ready;

    return true;

}

bool QBmpHandler::write(const QImage &img)

{

    QImage image;

    switch (img.format()) {

    case QImage::Format_Mono:

    case QImage::Format_Indexed8:

    case QImage::Format_RGB32:

    case QImage::Format_ARGB32:

        image = img;

        break;

    case QImage::Format_MonoLSB:

        image = img.convertToFormat(QImage::Format_Mono);

        break;

    case QImage::Format_Alpha8:

    case QImage::Format_Grayscale8:

        image = img.convertToFormat(QImage::Format_Indexed8);

        break;

    default:

        if (img.hasAlphaChannel())

            image = img.convertToFormat(QImage::Format_ARGB32);

        else

            image = img.convertToFormat(QImage::Format_RGB32);

        break;

    }

    int nbits;

    qsizetype bpl_bmp;

    // Calculate a minimum bytes-per-line instead of using whatever value this QImage is using internally.

    qsizetype bpl = ((image.width() * image.depth() + 31) >> 5) << 2;

    if (image.depth() == 8 && image.colorCount() <= 16) {

        bpl_bmp = (((bpl+1)/2+3)/4)*4;

        nbits = 4;

   } else if (image.depth() == 32) {

        bpl_bmp = ((image.width()*24+31)/32)*4;

        nbits = 24;

    } else {

        bpl_bmp = bpl;

        nbits = image.depth();

    }

    if (qsizetype(int(bpl_bmp)) != bpl_bmp)

        return false;

    if (m_format == DibFormat) {

        QDataStream dibStream(device());

        dibStream.setByteOrder(QDataStream::LittleEndian); // Intel byte order

        return qt_write_dib(dibStream, img, bpl, bpl_bmp, nbits);

    }

    QIODevice *d = device();

    QDataStream s(d);

    BMP_FILEHDR bf;

    // Intel byte order

    s.setByteOrder(QDataStream::LittleEndian);

    // build file header

    memcpy(bf.bfType, "BM", 2);

    // write file header

    bf.bfReserved1 = 0;

    bf.bfReserved2 = 0;

    bf.bfOffBits = BMP_FILEHDR_SIZE + BMP_WIN + image.colorCount() * 4;

    bf.bfSize = bf.bfOffBits + bpl_bmp*image.height();

    if (qsizetype(bf.bfSize) != bf.bfOffBits + bpl_bmp*image.height())

        return false;

    s << bf;

    // write image

    return qt_write_dib(s, image, bpl, bpl_bmp, nbits);

}

bool QBmpHandler::supportsOption(ImageOption option) const

{

    return option == Size

            || option == ImageFormat;

}

QVariant QBmpHandler::option(ImageOption option) const

{

    if (option == Size) {

        if (state == Error)

            return QVariant();

        if (state == Ready && !const_cast<QBmpHandler*>(this)->readHeader())

            return QVariant();

        return QSize(infoHeader.biWidth, infoHeader.biHeight);

    } else if (option == ImageFormat) {

        if (state == Error)

            return QVariant();

        if (state == Ready && !const_cast<QBmpHandler*>(this)->readHeader())

            return QVariant();

        QImage::Format format;

        switch (infoHeader.biBitCount) {

            case 32:

            case 24:

            case 16:

                if ((infoHeader.biCompression == BMP_BITFIELDS || infoHeader.biCompression == BMP_ALPHABITFIELDS) && infoHeader.biSize >= BMP_WIN4 && infoHeader.biAlphaMask)

                    format = QImage::Format_ARGB32;

                else

                    format = QImage::Format_RGB32;

                break;

            case 8:

            case 4:

                format = QImage::Format_Indexed8;

                break;

            default:

                format = QImage::Format_Mono;

            }

        return format;

    }

    return QVariant();

}

void QBmpHandler::setOption(ImageOption option, const QVariant &value)

{

    Q_UNUSED(option);

    Q_UNUSED(value);

}

QT_END_NAMESPACE

#endif // QT_NO_IMAGEFORMAT_BMP