diff options
| -rw-r--r-- | src/gui/painting/qdrawhelper.cpp | 12 | ||||
| -rw-r--r-- | src/gui/painting/qdrawhelper_p.h | 1 |
2 files changed, 7 insertions, 6 deletions
diff --git a/src/gui/painting/qdrawhelper.cpp b/src/gui/painting/qdrawhelper.cpp index a0f7155c67..ac22c7fc00 100644 --- a/src/gui/painting/qdrawhelper.cpp +++ b/src/gui/painting/qdrawhelper.cpp @@ -5754,9 +5754,9 @@ static inline void rgbBlendPixel(quint32 *dst, int coverage, int sr, int sg, int dg = gamma[dg]; db = gamma[db]; - int nr = qt_div_255((sr - dr) * mr) + dr; - int ng = qt_div_255((sg - dg) * mg) + dg; - int nb = qt_div_255((sb - db) * mb) + db; + int nr = qt_div_255(sr * mr + dr * (255 - mr)); + int ng = qt_div_255(sg * mg + dg * (255 - mg)); + int nb = qt_div_255(sb * mb + db * (255 - mb)); nr = invgamma[nr]; ng = invgamma[ng]; @@ -5781,9 +5781,9 @@ static inline void grayBlendPixel(quint32 *dst, int coverage, int sr, int sg, in int alpha = coverage; int ialpha = 255 - alpha; - int nr = (sr * alpha + ialpha * dr) / 255; - int ng = (sg * alpha + ialpha * dg) / 255; - int nb = (sb * alpha + ialpha * db) / 255; + int nr = qt_div_255(sr * alpha + dr * ialpha); + int ng = qt_div_255(sg * alpha + dg * ialpha); + int nb = qt_div_255(sb * alpha + db * ialpha); nr = invgamma[nr]; ng = invgamma[ng]; diff --git a/src/gui/painting/qdrawhelper_p.h b/src/gui/painting/qdrawhelper_p.h index ff98d186c5..d636eabe3f 100644 --- a/src/gui/painting/qdrawhelper_p.h +++ b/src/gui/painting/qdrawhelper_p.h @@ -705,6 +705,7 @@ static Q_ALWAYS_INLINE uint BYTE_MUL_RGB16_32(uint x, uint a) { return t; } +// qt_div_255 is a fast rounded division by 255 using an approximation that is accurate for all positive 16-bit integers static Q_DECL_CONSTEXPR Q_ALWAYS_INLINE int qt_div_255(int x) { return (x + (x>>8) + 0x80) >> 8; } static Q_DECL_CONSTEXPR Q_ALWAYS_INLINE uint qt_div_65535(uint x) { return (x + (x>>16) + 0x8000U) >> 16; } |