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      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 
     21 static const bool gUseUnpremul = false;
     22 
     23 class SkArithmeticMode_scalar : public SkXfermode {
     24 public:
     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 
     42 private:
     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 
     62 static 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 
     71 static 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 
     81 static int blend(int src, int dst, int scale) {
     82     return dst + ((src - dst) * scale >> 8);
     83 }
     84 
     85 static bool needsUnpremul(int alpha) {
     86     return 0 != alpha && 0xFF != alpha;
     87 }
     88 
     89 void 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
    173 void 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 
    186 static 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
    198 static 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 
    209 SkXfermode* 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 
    239 class GrGLArithmeticEffect : public GrGLEffect {
    240 public:
    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 
    254 private:
    255     GrGLUniformManager::UniformHandle fKUni;
    256 
    257     typedef GrGLEffect INHERITED;
    258 };
    259 
    260 ///////////////////////////////////////////////////////////////////////////////
    261 
    262 class GrArithmeticEffect : public GrEffect {
    263 public:
    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 
    284 private:
    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 
    299 GrArithmeticEffect::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 
    312 GrArithmeticEffect::~GrArithmeticEffect() {
    313 }
    314 
    315 bool 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 
    324 const GrBackendEffectFactory& GrArithmeticEffect::getFactory() const {
    325     return GrTBackendEffectFactory<GrArithmeticEffect>::getInstance();
    326 }
    327 
    328 void GrArithmeticEffect::getConstantColorComponents(GrColor* color, uint32_t* validFlags) const {
    329     // TODO: optimize this
    330     *validFlags = 0;
    331 }
    332 
    333 ///////////////////////////////////////////////////////////////////////////////
    334 
    335 GrGLArithmeticEffect::GrGLArithmeticEffect(const GrBackendEffectFactory& factory,
    336                                            const GrDrawEffect& drawEffect)
    337    : INHERITED(factory) {
    338 }
    339 
    340 GrGLArithmeticEffect::~GrGLArithmeticEffect() {
    341 }
    342 
    343 void 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 
    391 void 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 
    396 GrEffectRef* 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 
    409 GR_DEFINE_EFFECT_TEST(GrArithmeticEffect);
    410 
    411 bool 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 
    424 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(SkArithmeticMode)
    425     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkArithmeticMode_scalar)
    426 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END
    427