1/*
2 * Copyright 2013 Google Inc.
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 "SkArithmeticMode.h"
9#include "SkColorPriv.h"
10#include "SkFlattenableBuffers.h"
11#include "SkString.h"
12#include "SkUnPreMultiply.h"
13#if SK_SUPPORT_GPU
14#include "GrContext.h"
15#include "GrCoordTransform.h"
16#include "gl/GrGLEffect.h"
17#include "GrTBackendEffectFactory.h"
18#include "SkImageFilterUtils.h"
19#endif
20
21static const bool gUseUnpremul = false;
22
23class SkArithmeticMode_scalar : public SkXfermode {
24public:
25    SkArithmeticMode_scalar(SkScalar k1, SkScalar k2, SkScalar k3, SkScalar k4) {
26        fK[0] = k1;
27        fK[1] = k2;
28        fK[2] = k3;
29        fK[3] = k4;
30    }
31
32    virtual void xfer32(SkPMColor dst[], const SkPMColor src[], int count,
33                        const SkAlpha aa[]) const SK_OVERRIDE;
34
35    SK_DEVELOPER_TO_STRING()
36    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkArithmeticMode_scalar)
37
38#if SK_SUPPORT_GPU
39    virtual bool asNewEffect(GrEffectRef** effect, GrTexture* background) const SK_OVERRIDE;
40#endif
41
42private:
43    SkArithmeticMode_scalar(SkFlattenableReadBuffer& buffer) : INHERITED(buffer) {
44        fK[0] = buffer.readScalar();
45        fK[1] = buffer.readScalar();
46        fK[2] = buffer.readScalar();
47        fK[3] = buffer.readScalar();
48    }
49
50    virtual void flatten(SkFlattenableWriteBuffer& buffer) const SK_OVERRIDE {
51        INHERITED::flatten(buffer);
52        buffer.writeScalar(fK[0]);
53        buffer.writeScalar(fK[1]);
54        buffer.writeScalar(fK[2]);
55        buffer.writeScalar(fK[3]);
56    }
57    SkScalar fK[4];
58
59    typedef SkXfermode INHERITED;
60};
61
62static int pinToByte(int value) {
63    if (value < 0) {
64        value = 0;
65    } else if (value > 255) {
66        value = 255;
67    }
68    return value;
69}
70
71static int arith(SkScalar k1, SkScalar k2, SkScalar k3, SkScalar k4,
72                 int src, int dst) {
73    SkScalar result = SkScalarMul(k1, src * dst) +
74                      SkScalarMul(k2, src) +
75                      SkScalarMul(k3, dst) +
76                      k4;
77    int res = SkScalarRoundToInt(result);
78    return pinToByte(res);
79}
80
81static int blend(int src, int dst, int scale) {
82    return dst + ((src - dst) * scale >> 8);
83}
84
85static bool needsUnpremul(int alpha) {
86    return 0 != alpha && 0xFF != alpha;
87}
88
89void SkArithmeticMode_scalar::xfer32(SkPMColor dst[], const SkPMColor src[],
90                                 int count, const SkAlpha aaCoverage[]) const {
91    SkScalar k1 = fK[0] / 255;
92    SkScalar k2 = fK[1];
93    SkScalar k3 = fK[2];
94    SkScalar k4 = fK[3] * 255;
95
96    for (int i = 0; i < count; ++i) {
97        if ((NULL == aaCoverage) || aaCoverage[i]) {
98            SkPMColor sc = src[i];
99            SkPMColor dc = dst[i];
100
101            int a, r, g, b;
102
103            if (gUseUnpremul) {
104                int sa = SkGetPackedA32(sc);
105                int da = SkGetPackedA32(dc);
106
107                int srcNeedsUnpremul = needsUnpremul(sa);
108                int dstNeedsUnpremul = needsUnpremul(da);
109
110                if (!srcNeedsUnpremul && !dstNeedsUnpremul) {
111                    a = arith(k1, k2, k3, k4, sa, da);
112                    r = arith(k1, k2, k3, k4, SkGetPackedR32(sc), SkGetPackedR32(dc));
113                    g = arith(k1, k2, k3, k4, SkGetPackedG32(sc), SkGetPackedG32(dc));
114                    b = arith(k1, k2, k3, k4, SkGetPackedB32(sc), SkGetPackedB32(dc));
115                } else {
116                    int sr = SkGetPackedR32(sc);
117                    int sg = SkGetPackedG32(sc);
118                    int sb = SkGetPackedB32(sc);
119                    if (srcNeedsUnpremul) {
120                        SkUnPreMultiply::Scale scale = SkUnPreMultiply::GetScale(sa);
121                        sr = SkUnPreMultiply::ApplyScale(scale, sr);
122                        sg = SkUnPreMultiply::ApplyScale(scale, sg);
123                        sb = SkUnPreMultiply::ApplyScale(scale, sb);
124                    }
125
126                    int dr = SkGetPackedR32(dc);
127                    int dg = SkGetPackedG32(dc);
128                    int db = SkGetPackedB32(dc);
129                    if (dstNeedsUnpremul) {
130                        SkUnPreMultiply::Scale scale = SkUnPreMultiply::GetScale(da);
131                        dr = SkUnPreMultiply::ApplyScale(scale, dr);
132                        dg = SkUnPreMultiply::ApplyScale(scale, dg);
133                        db = SkUnPreMultiply::ApplyScale(scale, db);
134                    }
135
136                    a = arith(k1, k2, k3, k4, sa, da);
137                    r = arith(k1, k2, k3, k4, sr, dr);
138                    g = arith(k1, k2, k3, k4, sg, dg);
139                    b = arith(k1, k2, k3, k4, sb, db);
140                }
141            } else {
142                a = arith(k1, k2, k3, k4, SkGetPackedA32(sc), SkGetPackedA32(dc));
143                r = arith(k1, k2, k3, k4, SkGetPackedR32(sc), SkGetPackedR32(dc));
144                r = SkMin32(r, a);
145                g = arith(k1, k2, k3, k4, SkGetPackedG32(sc), SkGetPackedG32(dc));
146                g = SkMin32(g, a);
147                b = arith(k1, k2, k3, k4, SkGetPackedB32(sc), SkGetPackedB32(dc));
148                b = SkMin32(b, a);
149            }
150
151            // apply antialias coverage if necessary
152            if (aaCoverage && 0xFF != aaCoverage[i]) {
153                int scale = aaCoverage[i] + (aaCoverage[i] >> 7);
154                a = blend(a, SkGetPackedA32(sc), scale);
155                r = blend(r, SkGetPackedR32(sc), scale);
156                g = blend(g, SkGetPackedG32(sc), scale);
157                b = blend(b, SkGetPackedB32(sc), scale);
158            }
159
160            // turn the result back into premul
161            if (gUseUnpremul && (0xFF != a)) {
162                int scale = a + (a >> 7);
163                r = SkAlphaMul(r, scale);
164                g = SkAlphaMul(g, scale);
165                b = SkAlphaMul(b, scale);
166            }
167            dst[i] = SkPackARGB32(a, r, g, b);
168        }
169    }
170}
171
172#ifdef SK_DEVELOPER
173void SkArithmeticMode_scalar::toString(SkString* str) const {
174    str->append("SkArithmeticMode_scalar: ");
175    for (int i = 0; i < 4; ++i) {
176        str->appendScalar(fK[i]);
177        if (i < 3) {
178            str->append(" ");
179        }
180    }
181}
182#endif
183
184///////////////////////////////////////////////////////////////////////////////
185
186static bool fitsInBits(SkScalar x, int bits) {
187#ifdef SK_SCALAR_IS_FIXED
188    x = SkAbs32(x);
189    x += 1 << 7;
190    x >>= 8;
191    return x < (1 << (bits - 1));
192#else
193    return SkScalarAbs(x) < (1 << (bits - 1));
194#endif
195}
196
197#if 0 // UNUSED
198static int32_t toDot8(SkScalar x) {
199#ifdef SK_SCALAR_IS_FIXED
200    x += 1 << 7;
201    x >>= 8;
202    return x;
203#else
204    return (int32_t)(x * 256);
205#endif
206}
207#endif
208
209SkXfermode* SkArithmeticMode::Create(SkScalar k1, SkScalar k2,
210                                     SkScalar k3, SkScalar k4) {
211    if (fitsInBits(k1, 8) && fitsInBits(k2, 16) &&
212        fitsInBits(k2, 16) && fitsInBits(k2, 24)) {
213
214#if 0 // UNUSED
215        int32_t i1 = toDot8(k1);
216        int32_t i2 = toDot8(k2);
217        int32_t i3 = toDot8(k3);
218        int32_t i4 = toDot8(k4);
219        if (i1) {
220            return SkNEW_ARGS(SkArithmeticMode_quad, (i1, i2, i3, i4));
221        }
222        if (0 == i2) {
223            return SkNEW_ARGS(SkArithmeticMode_dst, (i3, i4));
224        }
225        if (0 == i3) {
226            return SkNEW_ARGS(SkArithmeticMode_src, (i2, i4));
227        }
228        return SkNEW_ARGS(SkArithmeticMode_linear, (i2, i3, i4));
229#endif
230    }
231    return SkNEW_ARGS(SkArithmeticMode_scalar, (k1, k2, k3, k4));
232}
233
234
235//////////////////////////////////////////////////////////////////////////////
236
237#if SK_SUPPORT_GPU
238
239class GrGLArithmeticEffect : public GrGLEffect {
240public:
241    GrGLArithmeticEffect(const GrBackendEffectFactory&, const GrDrawEffect&);
242    virtual ~GrGLArithmeticEffect();
243
244    virtual void emitCode(GrGLShaderBuilder*,
245                          const GrDrawEffect&,
246                          EffectKey,
247                          const char* outputColor,
248                          const char* inputColor,
249                          const TransformedCoordsArray&,
250                          const TextureSamplerArray&) SK_OVERRIDE;
251
252    virtual void setData(const GrGLUniformManager&, const GrDrawEffect&) SK_OVERRIDE;
253
254private:
255    GrGLUniformManager::UniformHandle fKUni;
256
257    typedef GrGLEffect INHERITED;
258};
259
260///////////////////////////////////////////////////////////////////////////////
261
262class GrArithmeticEffect : public GrEffect {
263public:
264    static GrEffectRef* Create(float k1, float k2, float k3, float k4, GrTexture* background) {
265        AutoEffectUnref effect(SkNEW_ARGS(GrArithmeticEffect, (k1, k2, k3, k4, background)));
266        return CreateEffectRef(effect);
267    }
268
269    virtual ~GrArithmeticEffect();
270
271    virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE;
272
273    typedef GrGLArithmeticEffect GLEffect;
274    static const char* Name() { return "Arithmetic"; }
275    GrTexture* backgroundTexture() const { return fBackgroundAccess.getTexture(); }
276
277    virtual void getConstantColorComponents(GrColor* color, uint32_t* validFlags) const SK_OVERRIDE;
278
279    float k1() const { return fK1; }
280    float k2() const { return fK2; }
281    float k3() const { return fK3; }
282    float k4() const { return fK4; }
283
284private:
285    virtual bool onIsEqual(const GrEffect&) const SK_OVERRIDE;
286
287    GrArithmeticEffect(float k1, float k2, float k3, float k4, GrTexture* background);
288    float                       fK1, fK2, fK3, fK4;
289    GrCoordTransform            fBackgroundTransform;
290    GrTextureAccess             fBackgroundAccess;
291
292    GR_DECLARE_EFFECT_TEST;
293    typedef GrEffect INHERITED;
294
295};
296
297///////////////////////////////////////////////////////////////////////////////
298
299GrArithmeticEffect::GrArithmeticEffect(float k1, float k2, float k3, float k4,
300                                       GrTexture* background)
301  : fK1(k1), fK2(k2), fK3(k3), fK4(k4) {
302    if (background) {
303        fBackgroundTransform.reset(kLocal_GrCoordSet, background);
304        this->addCoordTransform(&fBackgroundTransform);
305        fBackgroundAccess.reset(background);
306        this->addTextureAccess(&fBackgroundAccess);
307    } else {
308        this->setWillReadDstColor();
309    }
310}
311
312GrArithmeticEffect::~GrArithmeticEffect() {
313}
314
315bool GrArithmeticEffect::onIsEqual(const GrEffect& sBase) const {
316    const GrArithmeticEffect& s = CastEffect<GrArithmeticEffect>(sBase);
317    return fK1 == s.fK1 &&
318           fK2 == s.fK2 &&
319           fK3 == s.fK3 &&
320           fK4 == s.fK4 &&
321           backgroundTexture() == s.backgroundTexture();
322}
323
324const GrBackendEffectFactory& GrArithmeticEffect::getFactory() const {
325    return GrTBackendEffectFactory<GrArithmeticEffect>::getInstance();
326}
327
328void GrArithmeticEffect::getConstantColorComponents(GrColor* color, uint32_t* validFlags) const {
329    // TODO: optimize this
330    *validFlags = 0;
331}
332
333///////////////////////////////////////////////////////////////////////////////
334
335GrGLArithmeticEffect::GrGLArithmeticEffect(const GrBackendEffectFactory& factory,
336                                           const GrDrawEffect& drawEffect)
337   : INHERITED(factory) {
338}
339
340GrGLArithmeticEffect::~GrGLArithmeticEffect() {
341}
342
343void GrGLArithmeticEffect::emitCode(GrGLShaderBuilder* builder,
344                                    const GrDrawEffect& drawEffect,
345                                    EffectKey key,
346                                    const char* outputColor,
347                                    const char* inputColor,
348                                    const TransformedCoordsArray& coords,
349                                    const TextureSamplerArray& samplers) {
350
351    GrTexture* backgroundTex = drawEffect.castEffect<GrArithmeticEffect>().backgroundTexture();
352    const char* dstColor;
353    if (backgroundTex) {
354        builder->fsCodeAppend("\t\tvec4 bgColor = ");
355        builder->fsAppendTextureLookup(samplers[0], coords[0].c_str(), coords[0].type());
356        builder->fsCodeAppendf(";\n");
357        dstColor = "bgColor";
358    } else {
359        dstColor = builder->dstColor();
360    }
361
362    SkASSERT(NULL != dstColor);
363    fKUni = builder->addUniform(GrGLShaderBuilder::kFragment_Visibility,
364                                kVec4f_GrSLType, "k");
365    const char* kUni = builder->getUniformCStr(fKUni);
366
367    // We don't try to optimize for this case at all
368    if (NULL == inputColor) {
369        builder->fsCodeAppendf("\t\tconst vec4 src = vec4(1);\n");
370    } else {
371        builder->fsCodeAppendf("\t\tvec4 src = %s;\n", inputColor);
372        if (gUseUnpremul) {
373            builder->fsCodeAppendf("\t\tsrc.rgb = clamp(src.rgb / src.a, 0.0, 1.0);\n");
374        }
375    }
376
377    builder->fsCodeAppendf("\t\tvec4 dst = %s;\n", dstColor);
378    if (gUseUnpremul) {
379        builder->fsCodeAppendf("\t\tdst.rgb = clamp(dst.rgb / dst.a, 0.0, 1.0);\n");
380    }
381
382    builder->fsCodeAppendf("\t\t%s = %s.x * src * dst + %s.y * src + %s.z * dst + %s.w;\n", outputColor, kUni, kUni, kUni, kUni);
383    builder->fsCodeAppendf("\t\t%s = clamp(%s, 0.0, 1.0);\n", outputColor, outputColor);
384    if (gUseUnpremul) {
385        builder->fsCodeAppendf("\t\t%s.rgb *= %s.a;\n", outputColor, outputColor);
386    } else {
387        builder->fsCodeAppendf("\t\t%s.rgb = min(%s.rgb, %s.a);\n", outputColor, outputColor, outputColor);
388    }
389}
390
391void GrGLArithmeticEffect::setData(const GrGLUniformManager& uman, const GrDrawEffect& drawEffect) {
392    const GrArithmeticEffect& arith = drawEffect.castEffect<GrArithmeticEffect>();
393    uman.set4f(fKUni, arith.k1(), arith.k2(), arith.k3(), arith.k4());
394}
395
396GrEffectRef* GrArithmeticEffect::TestCreate(SkRandom* rand,
397                                            GrContext*,
398                                            const GrDrawTargetCaps&,
399                                            GrTexture*[]) {
400    float k1 = rand->nextF();
401    float k2 = rand->nextF();
402    float k3 = rand->nextF();
403    float k4 = rand->nextF();
404
405    AutoEffectUnref gEffect(SkNEW_ARGS(GrArithmeticEffect, (k1, k2, k3, k4, NULL)));
406    return CreateEffectRef(gEffect);
407}
408
409GR_DEFINE_EFFECT_TEST(GrArithmeticEffect);
410
411bool SkArithmeticMode_scalar::asNewEffect(GrEffectRef** effect, GrTexture* background) const {
412    if (effect) {
413        *effect = GrArithmeticEffect::Create(SkScalarToFloat(fK[0]),
414                                             SkScalarToFloat(fK[1]),
415                                             SkScalarToFloat(fK[2]),
416                                             SkScalarToFloat(fK[3]),
417                                             background);
418    }
419    return true;
420}
421
422#endif
423
424SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(SkArithmeticMode)
425    SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkArithmeticMode_scalar)
426SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END
427