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Diffstat (limited to 'utils/SkUnitMappers.cpp')
-rw-r--r-- | utils/SkUnitMappers.cpp | 61 |
1 files changed, 61 insertions, 0 deletions
diff --git a/utils/SkUnitMappers.cpp b/utils/SkUnitMappers.cpp new file mode 100644 index 00000000..ceff9ca0 --- /dev/null +++ b/utils/SkUnitMappers.cpp @@ -0,0 +1,61 @@ + +/* + * Copyright 2011 Google Inc. + * + * Use of this source code is governed by a BSD-style license that can be + * found in the LICENSE file. + */ +#include "SkUnitMappers.h" +#include "SkFlattenableBuffers.h" + +SK_DEFINE_INST_COUNT(SkUnitMapper) + +SkDiscreteMapper::SkDiscreteMapper(int segments) { + if (segments < 2) { + fSegments = 0; + fScale = 0; + } else { + if (segments > 0xFFFF) { + segments = 0xFFFF; + } + fSegments = segments; + fScale = SK_Fract1 / (segments - 1); + } +} + +uint16_t SkDiscreteMapper::mapUnit16(uint16_t input) { + SkFixed x = input * fSegments >> 16; + x = x * fScale >> 14; + x += x << 15 >> 31; // map 0x10000 to 0xFFFF + return SkToU16(x); +} + +SkDiscreteMapper::SkDiscreteMapper(SkFlattenableReadBuffer& rb) + : SkUnitMapper(rb) { + fSegments = rb.readInt(); + fScale = rb.read32(); +} + +void SkDiscreteMapper::flatten(SkFlattenableWriteBuffer& wb) const { + this->INHERITED::flatten(wb); + + wb.writeInt(fSegments); + wb.write32(fScale); +} + +/////////////////////////////////////////////////////////////////////////////// + +uint16_t SkCosineMapper::mapUnit16(uint16_t input) +{ + /* we want to call cosine(input * pi/2) treating input as [0...1) + however, the straight multitply would overflow 32bits since input is + 16bits and pi/2 is 17bits, so we shift down our pi const before we mul + */ + SkFixed rads = (unsigned)(input * (SK_FixedPI >> 2)) >> 15; + SkFixed x = SkFixedCos(rads); + x += x << 15 >> 31; // map 0x10000 to 0xFFFF + return SkToU16(x); +} + +SkCosineMapper::SkCosineMapper(SkFlattenableReadBuffer& rb) + : SkUnitMapper(rb) {} |