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