diff options
Diffstat (limited to 'src/core/SkBlitRow_D32.cpp')
-rw-r--r-- | src/core/SkBlitRow_D32.cpp | 27 |
1 files changed, 15 insertions, 12 deletions
diff --git a/src/core/SkBlitRow_D32.cpp b/src/core/SkBlitRow_D32.cpp index 36bfa54095..ac01e427bf 100644 --- a/src/core/SkBlitRow_D32.cpp +++ b/src/core/SkBlitRow_D32.cpp @@ -142,8 +142,11 @@ SkBlitRow::Proc32 SkBlitRow::ColorProcFactory() { #define SK_SUPPORT_LEGACY_COLOR32_MATHx -// Color32 and its SIMD specializations use the blend_perfect algorithm from tests/BlendTest.cpp. -// An acceptable alternative is blend_256_round_alt, which is faster but not quite perfect. +// Color32 and its SIMD specializations use the blend_256_round_alt algorithm +// from tests/BlendTest.cpp. It's not quite perfect, but it's never wrong in the +// interesting edge cases, and it's quite a bit faster than blend_perfect. +// +// blend_256_round_alt is our currently blessed algorithm. Please use it or an analogous one. void SkBlitRow::Color32(SkPMColor* SK_RESTRICT dst, const SkPMColor* SK_RESTRICT src, int count, SkPMColor color) { @@ -153,19 +156,19 @@ void SkBlitRow::Color32(SkPMColor* SK_RESTRICT dst, } unsigned invA = 255 - SkGetPackedA32(color); +#ifdef SK_SUPPORT_LEGACY_COLOR32_MATH // blend_256_plus1_trunc, busted + unsigned round = 0; +#else // blend_256_round_alt, good + invA += invA >> 7; + unsigned round = (128 << 16) + (128 << 0); +#endif + while (count --> 0) { // Our math is 16-bit, so we can do a little bit of SIMD in 32-bit registers. const uint32_t mask = 0x00FF00FF; - uint32_t rb = (((*src >> 0) & mask) * invA), // r_b_ - ag = (((*src >> 8) & mask) * invA); // a_g_ - #ifndef SK_SUPPORT_LEGACY_COLOR32_MATH - uint32_t round = (128 << 16) + (128 << 0); - rb += round; - ag += round; - rb += (rb & ~mask) >> 8; - ag += (ag & ~mask) >> 8; - #endif - *dst = color + (((rb>>8) & mask) | ((ag>>0) & ~mask)); + uint32_t rb = (((*src >> 0) & mask) * invA + round) >> 8, // _r_b + ag = (((*src >> 8) & mask) * invA + round) >> 0; // a_g_ + *dst = color + ((rb & mask) | (ag & ~mask)); src++; dst++; } |