1 /*
2 * Copyright 2014 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 "GrBicubicEffect.h"
9
10 #include "GrTexture.h"
11 #include "glsl/GrGLSLFragmentShaderBuilder.h"
12 #include "glsl/GrGLSLProgramDataManager.h"
13 #include "glsl/GrGLSLUniformHandler.h"
14 #include "../private/GrGLSL.h"
15
16 class GrGLBicubicEffect : public GrGLSLFragmentProcessor {
17 public:
18 void emitCode(EmitArgs&) override;
19
GenKey(const GrProcessor & effect,const GrShaderCaps &,GrProcessorKeyBuilder * b)20 static inline void GenKey(const GrProcessor& effect, const GrShaderCaps&,
21 GrProcessorKeyBuilder* b) {
22 const GrBicubicEffect& bicubicEffect = effect.cast<GrBicubicEffect>();
23 b->add32(GrTextureDomain::GLDomain::DomainKey(bicubicEffect.domain()));
24 }
25
26 protected:
27 void onSetData(const GrGLSLProgramDataManager&, const GrFragmentProcessor&) override;
28
29 private:
30 typedef GrGLSLProgramDataManager::UniformHandle UniformHandle;
31
32 UniformHandle fImageIncrementUni;
33 GrTextureDomain::GLDomain fDomain;
34
35 typedef GrGLSLFragmentProcessor INHERITED;
36 };
37
emitCode(EmitArgs & args)38 void GrGLBicubicEffect::emitCode(EmitArgs& args) {
39 const GrBicubicEffect& bicubicEffect = args.fFp.cast<GrBicubicEffect>();
40
41 GrGLSLUniformHandler* uniformHandler = args.fUniformHandler;
42 fImageIncrementUni = uniformHandler->addUniform(kFragment_GrShaderFlag, kHalf2_GrSLType,
43 "ImageIncrement");
44
45 const char* imgInc = uniformHandler->getUniformCStr(fImageIncrementUni);
46
47 GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
48 SkString coords2D = fragBuilder->ensureCoords2D(args.fTransformedCoords[0]);
49
50 /*
51 * Filter weights come from Don Mitchell & Arun Netravali's 'Reconstruction Filters in Computer
52 * Graphics', ACM SIGGRAPH Computer Graphics 22, 4 (Aug. 1988).
53 * ACM DL: http://dl.acm.org/citation.cfm?id=378514
54 * Free : http://www.cs.utexas.edu/users/fussell/courses/cs384g/lectures/mitchell/Mitchell.pdf
55 *
56 * The authors define a family of cubic filters with two free parameters (B and C):
57 *
58 * { (12 - 9B - 6C)|x|^3 + (-18 + 12B + 6C)|x|^2 + (6 - 2B) if |x| < 1
59 * k(x) = 1/6 { (-B - 6C)|x|^3 + (6B + 30C)|x|^2 + (-12B - 48C)|x| + (8B + 24C) if 1 <= |x| < 2
60 * { 0 otherwise
61 *
62 * Various well-known cubic splines can be generated, and the authors select (1/3, 1/3) as their
63 * favorite overall spline - this is now commonly known as the Mitchell filter, and is the
64 * source of the specific weights below.
65 *
66 * This is GLSL, so the matrix is column-major (transposed from standard matrix notation).
67 */
68 fragBuilder->codeAppend("half4x4 kMitchellCoefficients = half4x4("
69 " 1.0 / 18.0, 16.0 / 18.0, 1.0 / 18.0, 0.0 / 18.0,"
70 "-9.0 / 18.0, 0.0 / 18.0, 9.0 / 18.0, 0.0 / 18.0,"
71 "15.0 / 18.0, -36.0 / 18.0, 27.0 / 18.0, -6.0 / 18.0,"
72 "-7.0 / 18.0, 21.0 / 18.0, -21.0 / 18.0, 7.0 / 18.0);");
73 fragBuilder->codeAppendf("float2 coord = %s - %s * float2(0.5);", coords2D.c_str(), imgInc);
74 // We unnormalize the coord in order to determine our fractional offset (f) within the texel
75 // We then snap coord to a texel center and renormalize. The snap prevents cases where the
76 // starting coords are near a texel boundary and accumulations of imgInc would cause us to skip/
77 // double hit a texel.
78 fragBuilder->codeAppendf("coord /= %s;", imgInc);
79 fragBuilder->codeAppend("float2 f = fract(coord);");
80 fragBuilder->codeAppendf("coord = (coord - f + float2(0.5)) * %s;", imgInc);
81 fragBuilder->codeAppend("half4 wx = kMitchellCoefficients * half4(1.0, f.x, f.x * f.x, f.x * f.x * f.x);");
82 fragBuilder->codeAppend("half4 wy = kMitchellCoefficients * half4(1.0, f.y, f.y * f.y, f.y * f.y * f.y);");
83 fragBuilder->codeAppend("half4 rowColors[4];");
84 for (int y = 0; y < 4; ++y) {
85 for (int x = 0; x < 4; ++x) {
86 SkString coord;
87 coord.printf("coord + %s * float2(%d, %d)", imgInc, x - 1, y - 1);
88 SkString sampleVar;
89 sampleVar.printf("rowColors[%d]", x);
90 fDomain.sampleTexture(fragBuilder,
91 args.fUniformHandler,
92 args.fShaderCaps,
93 bicubicEffect.domain(),
94 sampleVar.c_str(),
95 coord,
96 args.fTexSamplers[0]);
97 }
98 fragBuilder->codeAppendf(
99 "half4 s%d = wx.x * rowColors[0] + wx.y * rowColors[1] + wx.z * rowColors[2] + wx.w * rowColors[3];",
100 y);
101 }
102 SkString bicubicColor("(wy.x * s0 + wy.y * s1 + wy.z * s2 + wy.w * s3)");
103 fragBuilder->codeAppendf("%s = %s * %s;", args.fOutputColor, bicubicColor.c_str(),
104 args.fInputColor);
105 }
106
onSetData(const GrGLSLProgramDataManager & pdman,const GrFragmentProcessor & processor)107 void GrGLBicubicEffect::onSetData(const GrGLSLProgramDataManager& pdman,
108 const GrFragmentProcessor& processor) {
109 const GrBicubicEffect& bicubicEffect = processor.cast<GrBicubicEffect>();
110 GrSurfaceProxy* proxy = processor.textureSampler(0).proxy();
111 GrTexture* texture = proxy->priv().peekTexture();
112
113 float imageIncrement[2];
114 imageIncrement[0] = 1.0f / texture->width();
115 imageIncrement[1] = 1.0f / texture->height();
116 pdman.set2fv(fImageIncrementUni, 1, imageIncrement);
117 fDomain.setData(pdman, bicubicEffect.domain(), proxy);
118 }
119
GrBicubicEffect(sk_sp<GrTextureProxy> proxy,const SkMatrix & matrix,const GrSamplerState::WrapMode wrapModes[2])120 GrBicubicEffect::GrBicubicEffect(sk_sp<GrTextureProxy> proxy,
121 const SkMatrix& matrix,
122 const GrSamplerState::WrapMode wrapModes[2])
123 : INHERITED{kGrBicubicEffect_ClassID, ModulateByConfigOptimizationFlags(proxy->config())}
124 , fCoordTransform(matrix, proxy.get())
125 , fDomain(GrTextureDomain::IgnoredDomain())
126 , fTextureSampler(std::move(proxy),
127 GrSamplerState(wrapModes, GrSamplerState::Filter::kNearest)) {
128 this->addCoordTransform(&fCoordTransform);
129 this->addTextureSampler(&fTextureSampler);
130 }
131
GrBicubicEffect(sk_sp<GrTextureProxy> proxy,const SkMatrix & matrix,const SkRect & domain)132 GrBicubicEffect::GrBicubicEffect(sk_sp<GrTextureProxy> proxy,
133 const SkMatrix& matrix,
134 const SkRect& domain)
135 : INHERITED(kGrBicubicEffect_ClassID, ModulateByConfigOptimizationFlags(proxy->config()))
136 , fCoordTransform(matrix, proxy.get())
137 , fDomain(proxy.get(), domain, GrTextureDomain::kClamp_Mode)
138 , fTextureSampler(std::move(proxy)) {
139 this->addCoordTransform(&fCoordTransform);
140 this->addTextureSampler(&fTextureSampler);
141 }
142
GrBicubicEffect(const GrBicubicEffect & that)143 GrBicubicEffect::GrBicubicEffect(const GrBicubicEffect& that)
144 : INHERITED(kGrBicubicEffect_ClassID, that.optimizationFlags())
145 , fCoordTransform(that.fCoordTransform)
146 , fDomain(that.fDomain)
147 , fTextureSampler(that.fTextureSampler) {
148 this->addCoordTransform(&fCoordTransform);
149 this->addTextureSampler(&fTextureSampler);
150 }
151
onGetGLSLProcessorKey(const GrShaderCaps & caps,GrProcessorKeyBuilder * b) const152 void GrBicubicEffect::onGetGLSLProcessorKey(const GrShaderCaps& caps,
153 GrProcessorKeyBuilder* b) const {
154 GrGLBicubicEffect::GenKey(*this, caps, b);
155 }
156
onCreateGLSLInstance() const157 GrGLSLFragmentProcessor* GrBicubicEffect::onCreateGLSLInstance() const {
158 return new GrGLBicubicEffect;
159 }
160
onIsEqual(const GrFragmentProcessor & sBase) const161 bool GrBicubicEffect::onIsEqual(const GrFragmentProcessor& sBase) const {
162 const GrBicubicEffect& s = sBase.cast<GrBicubicEffect>();
163 return fDomain == s.fDomain;
164 }
165
166 GR_DEFINE_FRAGMENT_PROCESSOR_TEST(GrBicubicEffect);
167
168 #if GR_TEST_UTILS
TestCreate(GrProcessorTestData * d)169 std::unique_ptr<GrFragmentProcessor> GrBicubicEffect::TestCreate(GrProcessorTestData* d) {
170 int texIdx = d->fRandom->nextBool() ? GrProcessorUnitTest::kSkiaPMTextureIdx
171 : GrProcessorUnitTest::kAlphaTextureIdx;
172 static const GrSamplerState::WrapMode kClampClamp[] = {GrSamplerState::WrapMode::kClamp,
173 GrSamplerState::WrapMode::kClamp};
174 return GrBicubicEffect::Make(d->textureProxy(texIdx), SkMatrix::I(), kClampClamp);
175 }
176 #endif
177
178 //////////////////////////////////////////////////////////////////////////////
179
ShouldUseBicubic(const SkMatrix & matrix,GrSamplerState::Filter * filterMode)180 bool GrBicubicEffect::ShouldUseBicubic(const SkMatrix& matrix, GrSamplerState::Filter* filterMode) {
181 if (matrix.isIdentity()) {
182 *filterMode = GrSamplerState::Filter::kNearest;
183 return false;
184 }
185
186 SkScalar scales[2];
187 if (!matrix.getMinMaxScales(scales) || scales[0] < SK_Scalar1) {
188 // Bicubic doesn't handle arbitrary minimization well, as src texels can be skipped
189 // entirely,
190 *filterMode = GrSamplerState::Filter::kMipMap;
191 return false;
192 }
193 // At this point if scales[1] == SK_Scalar1 then the matrix doesn't do any scaling.
194 if (scales[1] == SK_Scalar1) {
195 if (matrix.rectStaysRect() && SkScalarIsInt(matrix.getTranslateX()) &&
196 SkScalarIsInt(matrix.getTranslateY())) {
197 *filterMode = GrSamplerState::Filter::kNearest;
198 } else {
199 // Use bilerp to handle rotation or fractional translation.
200 *filterMode = GrSamplerState::Filter::kBilerp;
201 }
202 return false;
203 }
204 // When we use the bicubic filtering effect each sample is read from the texture using
205 // nearest neighbor sampling.
206 *filterMode = GrSamplerState::Filter::kNearest;
207 return true;
208 }
209