1/*
2 * Copyright 2006 The Android Open Source Project
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#include "SkAvoidXfermode.h"
9#include "SkColorPriv.h"
10#include "SkReadBuffer.h"
11#include "SkWriteBuffer.h"
12#include "SkString.h"
13
14SkAvoidXfermode::SkAvoidXfermode(SkColor opColor, U8CPU tolerance, Mode mode) {
15    if (tolerance > 255) {
16        tolerance = 255;
17    }
18
19    fOpColor = opColor;
20    fDistMul = (256 << 14) / (tolerance + 1);
21    fMode = mode;
22}
23
24SkAvoidXfermode::SkAvoidXfermode(SkReadBuffer& buffer)
25    : INHERITED(buffer) {
26    fOpColor = buffer.readColor();
27    fDistMul = buffer.readUInt();
28    fMode = (Mode)buffer.readUInt();
29}
30
31void SkAvoidXfermode::flatten(SkWriteBuffer& buffer) const {
32    this->INHERITED::flatten(buffer);
33
34    buffer.writeColor(fOpColor);
35    buffer.writeUInt(fDistMul);
36    buffer.writeUInt(fMode);
37}
38
39// returns 0..31
40static unsigned color_dist16(uint16_t c, unsigned r, unsigned g, unsigned b) {
41    SkASSERT(r <= SK_R16_MASK);
42    SkASSERT(g <= SK_G16_MASK);
43    SkASSERT(b <= SK_B16_MASK);
44
45    unsigned dr = SkAbs32(SkGetPackedR16(c) - r);
46    unsigned dg = SkAbs32(SkGetPackedG16(c) - g) >> (SK_G16_BITS - SK_R16_BITS);
47    unsigned db = SkAbs32(SkGetPackedB16(c) - b);
48
49    return SkMax32(dr, SkMax32(dg, db));
50}
51
52// returns 0..255
53static unsigned color_dist32(SkPMColor c, U8CPU r, U8CPU g, U8CPU b) {
54    SkASSERT(r <= 0xFF);
55    SkASSERT(g <= 0xFF);
56    SkASSERT(b <= 0xFF);
57
58    unsigned dr = SkAbs32(SkGetPackedR32(c) - r);
59    unsigned dg = SkAbs32(SkGetPackedG32(c) - g);
60    unsigned db = SkAbs32(SkGetPackedB32(c) - b);
61
62    return SkMax32(dr, SkMax32(dg, db));
63}
64
65static int scale_dist_14(int dist, uint32_t mul, uint32_t sub) {
66    int tmp = dist * mul - sub;
67    int result = (tmp + (1 << 13)) >> 14;
68
69    return result;
70}
71
72static inline unsigned Accurate255To256(unsigned x) {
73    return x + (x >> 7);
74}
75
76void SkAvoidXfermode::xfer32(SkPMColor dst[], const SkPMColor src[], int count,
77                             const SkAlpha aa[]) const {
78    unsigned    opR = SkColorGetR(fOpColor);
79    unsigned    opG = SkColorGetG(fOpColor);
80    unsigned    opB = SkColorGetB(fOpColor);
81    uint32_t    mul = fDistMul;
82    uint32_t    sub = (fDistMul - (1 << 14)) << 8;
83
84    int MAX, mask;
85
86    if (kTargetColor_Mode == fMode) {
87        mask = -1;
88        MAX = 255;
89    } else {
90        mask = 0;
91        MAX = 0;
92    }
93
94    for (int i = 0; i < count; i++) {
95        int d = color_dist32(dst[i], opR, opG, opB);
96        // now reverse d if we need to
97        d = MAX + (d ^ mask) - mask;
98        SkASSERT((unsigned)d <= 255);
99        d = Accurate255To256(d);
100
101        d = scale_dist_14(d, mul, sub);
102        SkASSERT(d <= 256);
103
104        if (d > 0) {
105            if (NULL != aa) {
106                d = SkAlphaMul(d, Accurate255To256(*aa++));
107                if (0 == d) {
108                    continue;
109                }
110            }
111            dst[i] = SkFourByteInterp256(src[i], dst[i], d);
112        }
113    }
114}
115
116static inline U16CPU SkBlend3216(SkPMColor src, U16CPU dst, unsigned scale) {
117    SkASSERT(scale <= 32);
118    scale <<= 3;
119
120    return SkPackRGB16( SkAlphaBlend(SkPacked32ToR16(src), SkGetPackedR16(dst), scale),
121                        SkAlphaBlend(SkPacked32ToG16(src), SkGetPackedG16(dst), scale),
122                        SkAlphaBlend(SkPacked32ToB16(src), SkGetPackedB16(dst), scale));
123}
124
125void SkAvoidXfermode::xfer16(uint16_t dst[], const SkPMColor src[], int count,
126                             const SkAlpha aa[]) const {
127    unsigned    opR = SkColorGetR(fOpColor) >> (8 - SK_R16_BITS);
128    unsigned    opG = SkColorGetG(fOpColor) >> (8 - SK_G16_BITS);
129    unsigned    opB = SkColorGetB(fOpColor) >> (8 - SK_R16_BITS);
130    uint32_t    mul = fDistMul;
131    uint32_t    sub = (fDistMul - (1 << 14)) << SK_R16_BITS;
132
133    int MAX, mask;
134
135    if (kTargetColor_Mode == fMode) {
136        mask = -1;
137        MAX = 31;
138    } else {
139        mask = 0;
140        MAX = 0;
141    }
142
143    for (int i = 0; i < count; i++) {
144        int d = color_dist16(dst[i], opR, opG, opB);
145        // now reverse d if we need to
146        d = MAX + (d ^ mask) - mask;
147        SkASSERT((unsigned)d <= 31);
148        // convert from 0..31 to 0..32
149        d += d >> 4;
150        d = scale_dist_14(d, mul, sub);
151        SkASSERT(d <= 32);
152
153        if (d > 0) {
154            if (NULL != aa) {
155                d = SkAlphaMul(d, Accurate255To256(*aa++));
156                if (0 == d) {
157                    continue;
158                }
159            }
160            dst[i] = SkBlend3216(src[i], dst[i], d);
161        }
162    }
163}
164
165void SkAvoidXfermode::xferA8(SkAlpha dst[], const SkPMColor src[], int count,
166                             const SkAlpha aa[]) const {
167    // override in subclass
168}
169
170#ifndef SK_IGNORE_TO_STRING
171void SkAvoidXfermode::toString(SkString* str) const {
172    str->append("SkAvoidXfermode: opColor: ");
173    str->appendHex(fOpColor);
174    str->appendf("distMul: %d ", fDistMul);
175
176    static const char* gModeStrings[] = { "Avoid", "Target" };
177
178    str->appendf("mode: %s", gModeStrings[fMode]);
179}
180#endif
181