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