1 2/* 3 * Copyright 2011 Google Inc. 4 * 5 * Use of this source code is governed by a BSD-style license that can be 6 * found in the LICENSE file. 7 */ 8#include "SkUnitMappers.h" 9 10SkDiscreteMapper::SkDiscreteMapper(int segments) { 11 if (segments < 2) { 12 fSegments = 0; 13 fScale = 0; 14 } else { 15 if (segments > 0xFFFF) { 16 segments = 0xFFFF; 17 } 18 fSegments = segments; 19 fScale = SK_Fract1 / (segments - 1); 20 } 21} 22 23uint16_t SkDiscreteMapper::mapUnit16(uint16_t input) { 24 SkFixed x = input * fSegments >> 16; 25 x = x * fScale >> 14; 26 x += x << 15 >> 31; // map 0x10000 to 0xFFFF 27 return SkToU16(x); 28} 29 30SkDiscreteMapper::SkDiscreteMapper(SkFlattenableReadBuffer& rb) 31 : SkUnitMapper(rb) { 32 fSegments = rb.readU32(); 33 fScale = rb.readU32(); 34} 35 36SkFlattenable::Factory SkDiscreteMapper::getFactory() { 37 return Create; 38} 39 40SkFlattenable* SkDiscreteMapper::Create(SkFlattenableReadBuffer& rb) { 41 return SkNEW_ARGS(SkDiscreteMapper, (rb)); 42} 43 44void SkDiscreteMapper::flatten(SkFlattenableWriteBuffer& wb) { 45 this->INHERITED::flatten(wb); 46 47 wb.write32(fSegments); 48 wb.write32(fScale); 49} 50 51/////////////////////////////////////////////////////////////////////////////// 52 53uint16_t SkCosineMapper::mapUnit16(uint16_t input) 54{ 55 /* we want to call cosine(input * pi/2) treating input as [0...1) 56 however, the straight multitply would overflow 32bits since input is 57 16bits and pi/2 is 17bits, so we shift down our pi const before we mul 58 */ 59 SkFixed rads = (unsigned)(input * (SK_FixedPI >> 2)) >> 15; 60 SkFixed x = SkFixedCos(rads); 61 x += x << 15 >> 31; // map 0x10000 to 0xFFFF 62 return SkToU16(x); 63} 64 65SkCosineMapper::SkCosineMapper(SkFlattenableReadBuffer& rb) 66 : SkUnitMapper(rb) {} 67 68SkFlattenable::Factory SkCosineMapper::getFactory() { 69 return Create; 70} 71 72SkFlattenable* SkCosineMapper::Create(SkFlattenableReadBuffer& rb) { 73 return SkNEW_ARGS(SkCosineMapper, (rb)); 74} 75 76