diff options
Diffstat (limited to 'src/gui/image')
-rw-r--r-- | src/gui/image/qbmphandler.cpp | 76 |
1 files changed, 50 insertions, 26 deletions
diff --git a/src/gui/image/qbmphandler.cpp b/src/gui/image/qbmphandler.cpp index 35e9875f20..b65ca923e5 100644 --- a/src/gui/image/qbmphandler.cpp +++ b/src/gui/image/qbmphandler.cpp @@ -135,16 +135,42 @@ static QDataStream &operator<<(QDataStream &s, const BMP_INFOHDR &bi) return s; } -static int calc_shift(uint mask) +static uint calc_shift(uint mask) { - int result = 0; - while (mask && !(mask & 1)) { + 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 @@ -207,14 +233,14 @@ static bool read_dib_body(QDataStream &s, const BMP_INFOHDR &bi, qint64 datapos, uint green_mask = 0; uint blue_mask = 0; uint alpha_mask = 0; - int red_shift = 0; - int green_shift = 0; - int blue_shift = 0; - int alpha_shift = 0; - int red_scale = 0; - int green_scale = 0; - int blue_scale = 0; - int alpha_scale = 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()) @@ -289,19 +315,19 @@ static bool read_dib_body(QDataStream &s, const BMP_INFOHDR &bi, qint64 datapos, red_shift = calc_shift(red_mask); if (((red_mask >> red_shift) + 1) == 0) return false; - red_scale = 256 / ((red_mask >> red_shift) + 1); + 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 = 256 / ((green_mask >> green_shift) + 1); + 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 = 256 / ((blue_mask >> blue_shift) + 1); + 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 = 256 / ((alpha_mask >> alpha_shift) + 1); + alpha_scale = calc_scale(alpha_mask >> alpha_shift); } else if (comp == BMP_RGB && (nbits == 24 || nbits == 32)) { blue_mask = 0x000000ff; green_mask = 0x0000ff00; @@ -309,23 +335,21 @@ static bool read_dib_body(QDataStream &s, const BMP_INFOHDR &bi, qint64 datapos, blue_shift = 0; green_shift = 8; red_shift = 16; - blue_scale = green_scale = red_scale = 1; + 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 = 256 / ((alpha_mask >> alpha_shift) + 1); + 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 = 2; - red_shift = 7; - red_scale = 1; - green_scale = 1; - blue_scale = 8; + green_shift = 5; + red_shift = 10; + blue_scale = green_scale = red_scale = 3; } image.setDotsPerMeterX(bi.biXPelsPerMeter); @@ -533,10 +557,10 @@ static bool read_dib_body(QDataStream &s, const BMP_INFOHDR &bi, qint64 datapos, c |= *(uchar*)(b+2)<<16; if (nbits > 24) c |= *(uchar*)(b+3)<<24; - *p++ = qRgba(((c & red_mask) >> red_shift) * red_scale, - ((c & green_mask) >> green_shift) * green_scale, - ((c & blue_mask) >> blue_shift) * blue_scale, - transp ? ((c & alpha_mask) >> alpha_shift) * alpha_scale : 0xff); + *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; } } |