SkAvoidXfermode.cpp revision b83b6b4f7690fe929d8d6b1a3d2b7ed562b95ba6 
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 "SkFlattenableBuffers.h"
11#include "SkString.h"
12
13SkAvoidXfermode::SkAvoidXfermode(SkColor opColor, U8CPU tolerance, Mode mode) {
14    if (tolerance > 255) {
15        tolerance = 255;
16    }
17
18    fOpColor = opColor;
19    fDistMul = (256 << 14) / (tolerance + 1);
20    fMode = mode;
21}
22
23SkAvoidXfermode::SkAvoidXfermode(SkFlattenableReadBuffer& buffer)
24    : INHERITED(buffer) {
25    fOpColor = buffer.readColor();
26    fDistMul = buffer.readUInt();
27    fMode = (Mode)buffer.readUInt();
28}
29
30void SkAvoidXfermode::flatten(SkFlattenableWriteBuffer& buffer) const {
31    this->INHERITED::flatten(buffer);
32
33    buffer.writeColor(fOpColor);
34    buffer.writeUInt(fDistMul);
35    buffer.writeUInt(fMode);
36}
37
38// returns 0..31
39static unsigned color_dist16(uint16_t c, unsigned r, unsigned g, unsigned b) {
40    SkASSERT(r <= SK_R16_MASK);
41    SkASSERT(g <= SK_G16_MASK);
42    SkASSERT(b <= SK_B16_MASK);
43
44    unsigned dr = SkAbs32(SkGetPackedR16(c) - r);
45    unsigned dg = SkAbs32(SkGetPackedG16(c) - g) >> (SK_G16_BITS - SK_R16_BITS);
46    unsigned db = SkAbs32(SkGetPackedB16(c) - b);
47
48    return SkMax32(dr, SkMax32(dg, db));
49}
50
51// returns 0..15
52static unsigned color_dist4444(uint16_t c, unsigned r, unsigned g, unsigned b) {
53    SkASSERT(r <= 0xF);
54    SkASSERT(g <= 0xF);
55    SkASSERT(b <= 0xF);
56
57    unsigned dr = SkAbs32(SkGetPackedR4444(c) - r);
58    unsigned dg = SkAbs32(SkGetPackedG4444(c) - g);
59    unsigned db = SkAbs32(SkGetPackedB4444(c) - b);
60
61    return SkMax32(dr, SkMax32(dg, db));
62}
63
64// returns 0..255
65static unsigned color_dist32(SkPMColor c, U8CPU r, U8CPU g, U8CPU b) {
66    SkASSERT(r <= 0xFF);
67    SkASSERT(g <= 0xFF);
68    SkASSERT(b <= 0xFF);
69
70    unsigned dr = SkAbs32(SkGetPackedR32(c) - r);
71    unsigned dg = SkAbs32(SkGetPackedG32(c) - g);
72    unsigned db = SkAbs32(SkGetPackedB32(c) - b);
73
74    return SkMax32(dr, SkMax32(dg, db));
75}
76
77static int scale_dist_14(int dist, uint32_t mul, uint32_t sub) {
78    int tmp = dist * mul - sub;
79    int result = (tmp + (1 << 13)) >> 14;
80
81    return result;
82}
83
84static inline unsigned Accurate255To256(unsigned x) {
85    return x + (x >> 7);
86}
87
88void SkAvoidXfermode::xfer32(SkPMColor dst[], const SkPMColor src[], int count,
89                             const SkAlpha aa[]) const {
90    unsigned    opR = SkColorGetR(fOpColor);
91    unsigned    opG = SkColorGetG(fOpColor);
92    unsigned    opB = SkColorGetB(fOpColor);
93    uint32_t    mul = fDistMul;
94    uint32_t    sub = (fDistMul - (1 << 14)) << 8;
95
96    int MAX, mask;
97
98    if (kTargetColor_Mode == fMode) {
99        mask = -1;
100        MAX = 255;
101    } else {
102        mask = 0;
103        MAX = 0;
104    }
105
106    for (int i = 0; i < count; i++) {
107        int d = color_dist32(dst[i], opR, opG, opB);
108        // now reverse d if we need to
109        d = MAX + (d ^ mask) - mask;
110        SkASSERT((unsigned)d <= 255);
111        d = Accurate255To256(d);
112
113        d = scale_dist_14(d, mul, sub);
114        SkASSERT(d <= 256);
115
116        if (d > 0) {
117            if (NULL != aa) {
118                d = SkAlphaMul(d, Accurate255To256(*aa++));
119                if (0 == d) {
120                    continue;
121                }
122            }
123            dst[i] = SkFourByteInterp256(src[i], dst[i], d);
124        }
125    }
126}
127
128static inline U16CPU SkBlend3216(SkPMColor src, U16CPU dst, unsigned scale) {
129    SkASSERT(scale <= 32);
130    scale <<= 3;
131
132    return SkPackRGB16( SkAlphaBlend(SkPacked32ToR16(src), SkGetPackedR16(dst), scale),
133                        SkAlphaBlend(SkPacked32ToG16(src), SkGetPackedG16(dst), scale),
134                        SkAlphaBlend(SkPacked32ToB16(src), SkGetPackedB16(dst), scale));
135}
136
137void SkAvoidXfermode::xfer16(uint16_t dst[], const SkPMColor src[], int count,
138                             const SkAlpha aa[]) const {
139    unsigned    opR = SkColorGetR(fOpColor) >> (8 - SK_R16_BITS);
140    unsigned    opG = SkColorGetG(fOpColor) >> (8 - SK_G16_BITS);
141    unsigned    opB = SkColorGetB(fOpColor) >> (8 - SK_R16_BITS);
142    uint32_t    mul = fDistMul;
143    uint32_t    sub = (fDistMul - (1 << 14)) << SK_R16_BITS;
144
145    int MAX, mask;
146
147    if (kTargetColor_Mode == fMode) {
148        mask = -1;
149        MAX = 31;
150    } else {
151        mask = 0;
152        MAX = 0;
153    }
154
155    for (int i = 0; i < count; i++) {
156        int d = color_dist16(dst[i], opR, opG, opB);
157        // now reverse d if we need to
158        d = MAX + (d ^ mask) - mask;
159        SkASSERT((unsigned)d <= 31);
160        // convert from 0..31 to 0..32
161        d += d >> 4;
162        d = scale_dist_14(d, mul, sub);
163        SkASSERT(d <= 32);
164
165        if (d > 0) {
166            if (NULL != aa) {
167                d = SkAlphaMul(d, Accurate255To256(*aa++));
168                if (0 == d) {
169                    continue;
170                }
171            }
172            dst[i] = SkBlend3216(src[i], dst[i], d);
173        }
174    }
175}
176
177void SkAvoidXfermode::xfer4444(uint16_t dst[], const SkPMColor src[], int count,
178                               const SkAlpha aa[]) const {
179    unsigned    opR = SkColorGetR(fOpColor) >> 4;
180    unsigned    opG = SkColorGetG(fOpColor) >> 4;
181    unsigned    opB = SkColorGetB(fOpColor) >> 4;
182    uint32_t    mul = fDistMul;
183    uint32_t    sub = (fDistMul - (1 << 14)) << 4;
184
185    int MAX, mask;
186
187    if (kTargetColor_Mode == fMode) {
188        mask = -1;
189        MAX = 15;
190    } else {
191        mask = 0;
192        MAX = 0;
193    }
194
195    for (int i = 0; i < count; i++) {
196        int d = color_dist4444(dst[i], opR, opG, opB);
197        // now reverse d if we need to
198        d = MAX + (d ^ mask) - mask;
199        SkASSERT((unsigned)d <= 15);
200        // convert from 0..15 to 0..16
201        d += d >> 3;
202        d = scale_dist_14(d, mul, sub);
203        SkASSERT(d <= 16);
204
205        if (d > 0) {
206            if (NULL != aa) {
207                d = SkAlphaMul(d, Accurate255To256(*aa++));
208                if (0 == d) {
209                    continue;
210                }
211            }
212            dst[i] = SkBlend4444(SkPixel32ToPixel4444(src[i]), dst[i], d);
213        }
214    }
215}
216
217void SkAvoidXfermode::xferA8(SkAlpha dst[], const SkPMColor src[], int count,
218                             const SkAlpha aa[]) const {
219    // override in subclass
220}
221
222#ifdef SK_DEVELOPER
223void SkAvoidXfermode::toString(SkString* str) const {
224    str->append("SkAvoidXfermode: opColor: ");
225    str->appendHex(fOpColor);
226    str->appendf("distMul: %d ", fDistMul);
227
228    static const char* gModeStrings[] = { "Avoid", "Target" };
229
230    str->appendf("mode: %s", gModeStrings[fMode]);
231}
232#endif
233