aboutsummaryrefslogtreecommitdiffhomepage
path: root/src/effects/SkArithmeticMode.cpp
blob: 4914c696ee57eb5267a5d4f3a353195077ee1a6b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
/*
 * Copyright 2013 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "SkArithmeticMode.h"
#include "SkColorPriv.h"
#include "SkReadBuffer.h"
#include "SkWriteBuffer.h"
#include "SkString.h"
#include "SkUnPreMultiply.h"
#if SK_SUPPORT_GPU
#include "SkArithmeticMode_gpu.h"
#endif

static const bool gUseUnpremul = false;

class SkArithmeticMode_scalar : public SkXfermode {
public:
    static SkArithmeticMode_scalar* Create(SkScalar k1, SkScalar k2, SkScalar k3, SkScalar k4,
                                           bool enforcePMColor) {
        return SkNEW_ARGS(SkArithmeticMode_scalar, (k1, k2, k3, k4, enforcePMColor));
    }

    virtual void xfer32(SkPMColor dst[], const SkPMColor src[], int count,
                        const SkAlpha aa[]) const override;

    SK_TO_STRING_OVERRIDE()
    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkArithmeticMode_scalar)

#if SK_SUPPORT_GPU
    bool asFragmentProcessor(GrFragmentProcessor**, GrTexture* background) const override;

    bool asXPFactory(GrXPFactory**) const override;
#endif

private:
    SkArithmeticMode_scalar(SkScalar k1, SkScalar k2, SkScalar k3, SkScalar k4, bool enforcePMColor) {
        fK[0] = k1;
        fK[1] = k2;
        fK[2] = k3;
        fK[3] = k4;
        fEnforcePMColor = enforcePMColor;
    }

    void flatten(SkWriteBuffer& buffer) const override {
        buffer.writeScalar(fK[0]);
        buffer.writeScalar(fK[1]);
        buffer.writeScalar(fK[2]);
        buffer.writeScalar(fK[3]);
        buffer.writeBool(fEnforcePMColor);
    }
    SkScalar fK[4];
    bool fEnforcePMColor;

    friend class SkArithmeticMode;

    typedef SkXfermode INHERITED;
};

SkFlattenable* SkArithmeticMode_scalar::CreateProc(SkReadBuffer& buffer) {
    const SkScalar k1 = buffer.readScalar();
    const SkScalar k2 = buffer.readScalar();
    const SkScalar k3 = buffer.readScalar();
    const SkScalar k4 = buffer.readScalar();
    const bool enforcePMColor = buffer.readBool();
    return Create(k1, k2, k3, k4, enforcePMColor);
}

static int pinToByte(int value) {
    if (value < 0) {
        value = 0;
    } else if (value > 255) {
        value = 255;
    }
    return value;
}

static int arith(SkScalar k1, SkScalar k2, SkScalar k3, SkScalar k4,
                 int src, int dst) {
    SkScalar result = SkScalarMul(k1, src * dst) +
                      SkScalarMul(k2, src) +
                      SkScalarMul(k3, dst) +
                      k4;
    int res = SkScalarRoundToInt(result);
    return pinToByte(res);
}

static int blend(int src, int dst, int scale) {
    return dst + ((src - dst) * scale >> 8);
}

static bool needsUnpremul(int alpha) {
    return 0 != alpha && 0xFF != alpha;
}

void SkArithmeticMode_scalar::xfer32(SkPMColor dst[], const SkPMColor src[],
                                 int count, const SkAlpha aaCoverage[]) const {
    SkScalar k1 = fK[0] / 255;
    SkScalar k2 = fK[1];
    SkScalar k3 = fK[2];
    SkScalar k4 = fK[3] * 255;

    for (int i = 0; i < count; ++i) {
        if ((NULL == aaCoverage) || aaCoverage[i]) {
            SkPMColor sc = src[i];
            SkPMColor dc = dst[i];

            int a, r, g, b;

            if (gUseUnpremul) {
                int sa = SkGetPackedA32(sc);
                int da = SkGetPackedA32(dc);

                int srcNeedsUnpremul = needsUnpremul(sa);
                int dstNeedsUnpremul = needsUnpremul(da);

                if (!srcNeedsUnpremul && !dstNeedsUnpremul) {
                    a = arith(k1, k2, k3, k4, sa, da);
                    r = arith(k1, k2, k3, k4, SkGetPackedR32(sc), SkGetPackedR32(dc));
                    g = arith(k1, k2, k3, k4, SkGetPackedG32(sc), SkGetPackedG32(dc));
                    b = arith(k1, k2, k3, k4, SkGetPackedB32(sc), SkGetPackedB32(dc));
                } else {
                    int sr = SkGetPackedR32(sc);
                    int sg = SkGetPackedG32(sc);
                    int sb = SkGetPackedB32(sc);
                    if (srcNeedsUnpremul) {
                        SkUnPreMultiply::Scale scale = SkUnPreMultiply::GetScale(sa);
                        sr = SkUnPreMultiply::ApplyScale(scale, sr);
                        sg = SkUnPreMultiply::ApplyScale(scale, sg);
                        sb = SkUnPreMultiply::ApplyScale(scale, sb);
                    }

                    int dr = SkGetPackedR32(dc);
                    int dg = SkGetPackedG32(dc);
                    int db = SkGetPackedB32(dc);
                    if (dstNeedsUnpremul) {
                        SkUnPreMultiply::Scale scale = SkUnPreMultiply::GetScale(da);
                        dr = SkUnPreMultiply::ApplyScale(scale, dr);
                        dg = SkUnPreMultiply::ApplyScale(scale, dg);
                        db = SkUnPreMultiply::ApplyScale(scale, db);
                    }

                    a = arith(k1, k2, k3, k4, sa, da);
                    r = arith(k1, k2, k3, k4, sr, dr);
                    g = arith(k1, k2, k3, k4, sg, dg);
                    b = arith(k1, k2, k3, k4, sb, db);
                }
            } else {
                a = arith(k1, k2, k3, k4, SkGetPackedA32(sc), SkGetPackedA32(dc));
                r = arith(k1, k2, k3, k4, SkGetPackedR32(sc), SkGetPackedR32(dc));
                g = arith(k1, k2, k3, k4, SkGetPackedG32(sc), SkGetPackedG32(dc));
                b = arith(k1, k2, k3, k4, SkGetPackedB32(sc), SkGetPackedB32(dc));
                if (fEnforcePMColor) {
                    r = SkMin32(r, a);
                    g = SkMin32(g, a);
                    b = SkMin32(b, a);
                }
            }

            // apply antialias coverage if necessary
            if (aaCoverage && 0xFF != aaCoverage[i]) {
                int scale = aaCoverage[i] + (aaCoverage[i] >> 7);
                a = blend(a, SkGetPackedA32(sc), scale);
                r = blend(r, SkGetPackedR32(sc), scale);
                g = blend(g, SkGetPackedG32(sc), scale);
                b = blend(b, SkGetPackedB32(sc), scale);
            }

            // turn the result back into premul
            if (gUseUnpremul && (0xFF != a)) {
                int scale = a + (a >> 7);
                r = SkAlphaMul(r, scale);
                g = SkAlphaMul(g, scale);
                b = SkAlphaMul(b, scale);
            }
            dst[i] = fEnforcePMColor ? SkPackARGB32(a, r, g, b) : SkPackARGB32NoCheck(a, r, g, b);
        }
    }
}

#ifndef SK_IGNORE_TO_STRING
void SkArithmeticMode_scalar::toString(SkString* str) const {
    str->append("SkArithmeticMode_scalar: ");
    for (int i = 0; i < 4; ++i) {
        str->appendScalar(fK[i]);
        str->append(" ");
    }
    str->appendS32(fEnforcePMColor ? 1 : 0);
}
#endif

///////////////////////////////////////////////////////////////////////////////

static bool fitsInBits(SkScalar x, int bits) {
    return SkScalarAbs(x) < (1 << (bits - 1));
}

#if 0 // UNUSED
static int32_t toDot8(SkScalar x) {
    return (int32_t)(x * 256);
}
#endif

SkXfermode* SkArithmeticMode::Create(SkScalar k1, SkScalar k2,
                                     SkScalar k3, SkScalar k4,
                                     bool enforcePMColor) {
    if (fitsInBits(k1, 8) && fitsInBits(k2, 16) &&
        fitsInBits(k2, 16) && fitsInBits(k2, 24)) {

#if 0 // UNUSED
        int32_t i1 = toDot8(k1);
        int32_t i2 = toDot8(k2);
        int32_t i3 = toDot8(k3);
        int32_t i4 = toDot8(k4);
        if (i1) {
            return SkNEW_ARGS(SkArithmeticMode_quad, (i1, i2, i3, i4));
        }
        if (0 == i2) {
            return SkNEW_ARGS(SkArithmeticMode_dst, (i3, i4));
        }
        if (0 == i3) {
            return SkNEW_ARGS(SkArithmeticMode_src, (i2, i4));
        }
        return SkNEW_ARGS(SkArithmeticMode_linear, (i2, i3, i4));
#endif
    }
    return SkArithmeticMode_scalar::Create(k1, k2, k3, k4, enforcePMColor);
}


//////////////////////////////////////////////////////////////////////////////

#if SK_SUPPORT_GPU
bool SkArithmeticMode_scalar::asFragmentProcessor(GrFragmentProcessor** fp,
                                                  GrTexture* background) const {
    if (fp) {
        *fp = GrArithmeticFP::Create(SkScalarToFloat(fK[0]),
                                     SkScalarToFloat(fK[1]),
                                     SkScalarToFloat(fK[2]),
                                     SkScalarToFloat(fK[3]),
                                     fEnforcePMColor,
                                     background);
    }
    return true;
}

bool SkArithmeticMode_scalar::asXPFactory(GrXPFactory** xpf) const {
    if (xpf) {
        *xpf = GrArithmeticXPFactory::Create(SkScalarToFloat(fK[0]),
                                             SkScalarToFloat(fK[1]),
                                             SkScalarToFloat(fK[2]),
                                             SkScalarToFloat(fK[3]),
                                             fEnforcePMColor);
    }
    return true;
}

#endif

SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(SkArithmeticMode)
    SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkArithmeticMode_scalar)
SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END