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| author | Mike Reed <reed@google.com> | 2010-03-12 14:22:51 -0500 |
|---|---|---|
| committer | Mike Reed <reed@google.com> | 2010-03-12 14:22:51 -0500 |
| commit | 4ffbc6172403ee38fc70608377ce78c9db00394a (patch) | |
| tree | d04eb3706773a2a56e58d8942a35e3915fd02e9a | |
| parent | d7d0da62bf31ccc5550f526fc10c01cd24f81af9 (diff) | |
| download | skia-4ffbc6172403ee38fc70608377ce78c9db00394a.tar.gz | |
improve precision of blend
fixes http://b/issue?id=2136225
Change-Id: Ifa01a04406e1b53ffbd12a29a81445eeb60f0e60
| -rw-r--r-- | src/effects/SkAvoidXfermode.cpp | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/src/effects/SkAvoidXfermode.cpp b/src/effects/SkAvoidXfermode.cpp index d26039cec9..97bfeae0b2 100644 --- a/src/effects/SkAvoidXfermode.cpp +++ b/src/effects/SkAvoidXfermode.cpp @@ -116,6 +116,10 @@ static SkPMColor SkFourByteInterp(SkPMColor src, SkPMColor dst, unsigned scale) return SkPackARGB32(a, r, g, b); } +static inline unsigned Accurate255To256(unsigned x) { + return x + (x >> 7); +} + void SkAvoidXfermode::xfer32(SkPMColor dst[], const SkPMColor src[], int count, const SkAlpha aa[]) { @@ -140,14 +144,14 @@ void SkAvoidXfermode::xfer32(SkPMColor dst[], const SkPMColor src[], int count, // now reverse d if we need to d = MAX + (d ^ mask) - mask; SkASSERT((unsigned)d <= 255); - d = SkAlpha255To256(d); + d = Accurate255To256(d); d = scale_dist_14(d, mul, sub); SkASSERT(d <= 256); if (d > 0) { if (NULL != aa) { - d = SkAlphaMul(d, SkAlpha255To256(*aa++)); + d = SkAlphaMul(d, Accurate255To256(*aa++)); if (0 == d) { continue; } @@ -198,7 +202,7 @@ void SkAvoidXfermode::xfer16(uint16_t dst[], const SkPMColor src[], int count, if (d > 0) { if (NULL != aa) { - d = SkAlphaMul(d, SkAlpha255To256(*aa++)); + d = SkAlphaMul(d, Accurate255To256(*aa++)); if (0 == d) { continue; } @@ -239,7 +243,7 @@ void SkAvoidXfermode::xfer4444(uint16_t dst[], const SkPMColor src[], int count, if (d > 0) { if (NULL != aa) { - d = SkAlphaMul(d, SkAlpha255To256(*aa++)); + d = SkAlphaMul(d, Accurate255To256(*aa++)); if (0 == d) { continue; } |