diff options
| -rw-r--r-- | src/core/SkBitmapProcState_matrix.h | 17 | ||||
| -rw-r--r-- | src/core/SkBitmapProcState_matrixProcs.cpp | 29 |
2 files changed, 35 insertions, 11 deletions
diff --git a/src/core/SkBitmapProcState_matrix.h b/src/core/SkBitmapProcState_matrix.h index 5ea780e9b7..469cbf3ad4 100644 --- a/src/core/SkBitmapProcState_matrix.h +++ b/src/core/SkBitmapProcState_matrix.h @@ -71,12 +71,9 @@ void SCALE_NOFILTER_NAME(const SkBitmapProcState& s, const SkFractionalInt dx = s.fInvSxFractionalInt; #ifdef CHECK_FOR_DECAL - // test if we don't need to apply the tile proc - SkFixed tmpFx = SkFractionalIntToFixed(fx); - SkFixed tmpDx = SkFractionalIntToFixed(dx); - if ((unsigned)(tmpFx >> 16) <= maxX && - (unsigned)((tmpFx + tmpDx * (count - 1)) >> 16) <= maxX) { - decal_nofilter_scale(xy, tmpFx, tmpDx, count); + if (can_truncate_to_fixed_for_decal(fx, dx, count, maxX)) { + decal_nofilter_scale(xy, SkFractionalIntToFixed(fx), + SkFractionalIntToFixed(dx), count); } else #endif { @@ -201,11 +198,9 @@ void SCALE_FILTER_NAME(const SkBitmapProcState& s, } #ifdef CHECK_FOR_DECAL - // test if we don't need to apply the tile proc - if (dx > 0 && - (unsigned)(fx >> 16) <= maxX && - (unsigned)((fx + dx * (count - 1)) >> 16) < maxX) { - decal_filter_scale(xy, (SkFixed) fx, (SkFixed) dx, count); + if (can_truncate_to_fixed_for_decal(fx, dx, count, maxX)) { + decal_filter_scale(xy, SkFractionalIntToFixed(fx), + SkFractionalIntToFixed(dx), count); } else #endif { diff --git a/src/core/SkBitmapProcState_matrixProcs.cpp b/src/core/SkBitmapProcState_matrixProcs.cpp index c043e8610c..1e12f9a921 100644 --- a/src/core/SkBitmapProcState_matrixProcs.cpp +++ b/src/core/SkBitmapProcState_matrixProcs.cpp @@ -35,6 +35,35 @@ static inline int sk_int_mod(int x, int n) { return x; } +/* + * The decal_ functions require that + * 1. dx > 0 + * 2. [fx, fx+dx, fx+2dx, fx+3dx, ... fx+(count-1)dx] are all <= maxX + * + * In addition, we use SkFractionalInt to keep more fractional precision than + * just SkFixed, so we will abort the decal_ call if dx is very small, since + * the decal_ function just operates on SkFixed. If that were changed, we could + * skip the very_small test here. + */ +static inline bool can_truncate_to_fixed_for_decal(SkFractionalInt frX, + SkFractionalInt frDx, + int count, unsigned max) { + SkFixed dx = SkFractionalIntToFixed(frDx); + + // if decal_ kept SkFractionalInt precision, this would just be dx <= 0 + // I just made up the 1/256. Just don't want to perceive accumulated error + // if we truncate frDx and lose its low bits. + if (dx <= SK_Fixed1 / 256) { + return false; + } + + // We cast to unsigned so we don't have to check for negative values, which + // will now appear as very large positive values, and thus fail our test! + SkFixed fx = SkFractionalIntToFixed(frX); + return (unsigned)SkFixedFloorToInt(fx) <= max && + (unsigned)SkFixedFloorToInt(fx + dx * (count - 1)) < max; +} + void decal_nofilter_scale(uint32_t dst[], SkFixed fx, SkFixed dx, int count); void decal_filter_scale(uint32_t dst[], SkFixed fx, SkFixed dx, int count); |