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
15 class GrGLBicubicEffect : public GrGLSLFragmentProcessor {
16 public:
17 void emitCode(EmitArgs&) override;
18
GenKey(const GrProcessor & effect,const GrShaderCaps &,GrProcessorKeyBuilder * b)19 static inline void GenKey(const GrProcessor& effect, const GrShaderCaps&,
20 GrProcessorKeyBuilder* b) {
21 const GrBicubicEffect& bicubicEffect = effect.cast<GrBicubicEffect>();
22 b->add32(GrTextureDomain::GLDomain::DomainKey(bicubicEffect.domain()));
23 }
24
25 protected:
26 void onSetData(const GrGLSLProgramDataManager&, const GrFragmentProcessor&) override;
27
28 private:
29 typedef GrGLSLProgramDataManager::UniformHandle UniformHandle;
30
31 UniformHandle fImageIncrementUni;
32 GrTextureDomain::GLDomain fDomain;
33
34 typedef GrGLSLFragmentProcessor INHERITED;
35 };
36
emitCode(EmitArgs & args)37 void GrGLBicubicEffect::emitCode(EmitArgs& args) {
38 const GrBicubicEffect& bicubicEffect = args.fFp.cast<GrBicubicEffect>();
39
40 GrGLSLUniformHandler* uniformHandler = args.fUniformHandler;
41 fImageIncrementUni = uniformHandler->addUniform(kFragment_GrShaderFlag, kHalf2_GrSLType,
42 "ImageIncrement");
43
44 const char* imgInc = uniformHandler->getUniformCStr(fImageIncrementUni);
45
46 GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
47 SkString coords2D = fragBuilder->ensureCoords2D(args.fTransformedCoords[0]);
48
49 /*
50 * Filter weights come from Don Mitchell & Arun Netravali's 'Reconstruction Filters in Computer
51 * Graphics', ACM SIGGRAPH Computer Graphics 22, 4 (Aug. 1988).
52 * ACM DL: http://dl.acm.org/citation.cfm?id=378514
53 * Free : http://www.cs.utexas.edu/users/fussell/courses/cs384g/lectures/mitchell/Mitchell.pdf
54 *
55 * The authors define a family of cubic filters with two free parameters (B and C):
56 *
57 * { (12 - 9B - 6C)|x|^3 + (-18 + 12B + 6C)|x|^2 + (6 - 2B) if |x| < 1
58 * k(x) = 1/6 { (-B - 6C)|x|^3 + (6B + 30C)|x|^2 + (-12B - 48C)|x| + (8B + 24C) if 1 <= |x| < 2
59 * { 0 otherwise
60 *
61 * Various well-known cubic splines can be generated, and the authors select (1/3, 1/3) as their
62 * favorite overall spline - this is now commonly known as the Mitchell filter, and is the
63 * source of the specific weights below.
64 *
65 * This is GLSL, so the matrix is column-major (transposed from standard matrix notation).
66 */
67 fragBuilder->codeAppend("half4x4 kMitchellCoefficients = half4x4("
68 " 1.0 / 18.0, 16.0 / 18.0, 1.0 / 18.0, 0.0 / 18.0,"
69 "-9.0 / 18.0, 0.0 / 18.0, 9.0 / 18.0, 0.0 / 18.0,"
70 "15.0 / 18.0, -36.0 / 18.0, 27.0 / 18.0, -6.0 / 18.0,"
71 "-7.0 / 18.0, 21.0 / 18.0, -21.0 / 18.0, 7.0 / 18.0);");
72 fragBuilder->codeAppendf("float2 coord = %s - %s * float2(0.5);", coords2D.c_str(), imgInc);
73 // We unnormalize the coord in order to determine our fractional offset (f) within the texel
74 // We then snap coord to a texel center and renormalize. The snap prevents cases where the
75 // starting coords are near a texel boundary and accumulations of imgInc would cause us to skip/
76 // double hit a texel.
77 fragBuilder->codeAppendf("coord /= %s;", imgInc);
78 fragBuilder->codeAppend("float2 f = fract(coord);");
79 fragBuilder->codeAppendf("coord = (coord - f + float2(0.5)) * %s;", imgInc);
80 fragBuilder->codeAppend("half4 wx = kMitchellCoefficients * half4(1.0, f.x, f.x * f.x, f.x * f.x * f.x);");
81 fragBuilder->codeAppend("half4 wy = kMitchellCoefficients * half4(1.0, f.y, f.y * f.y, f.y * f.y * f.y);");
82 fragBuilder->codeAppend("half4 rowColors[4];");
83 for (int y = 0; y < 4; ++y) {
84 for (int x = 0; x < 4; ++x) {
85 SkString coord;
86 coord.printf("coord + %s * float2(%d, %d)", imgInc, x - 1, y - 1);
87 SkString sampleVar;
88 sampleVar.printf("rowColors[%d]", x);
89 fDomain.sampleTexture(fragBuilder,
90 args.fUniformHandler,
91 args.fShaderCaps,
92 bicubicEffect.domain(),
93 sampleVar.c_str(),
94 coord,
95 args.fTexSamplers[0]);
96 }
97 fragBuilder->codeAppendf(
98 "half4 s%d = wx.x * rowColors[0] + wx.y * rowColors[1] + wx.z * rowColors[2] + wx.w * rowColors[3];",
99 y);
100 }
101 SkString bicubicColor("(wy.x * s0 + wy.y * s1 + wy.z * s2 + wy.w * s3)");
102 fragBuilder->codeAppendf("%s = %s * %s;", args.fOutputColor, bicubicColor.c_str(),
103 args.fInputColor);
104 }
105
onSetData(const GrGLSLProgramDataManager & pdman,const GrFragmentProcessor & processor)106 void GrGLBicubicEffect::onSetData(const GrGLSLProgramDataManager& pdman,
107 const GrFragmentProcessor& processor) {
108 const GrBicubicEffect& bicubicEffect = processor.cast<GrBicubicEffect>();
109 GrTextureProxy* proxy = processor.textureSampler(0).proxy();
110 GrTexture* texture = proxy->peekTexture();
111
112 float imageIncrement[2];
113 imageIncrement[0] = 1.0f / texture->width();
114 imageIncrement[1] = 1.0f / texture->height();
115 pdman.set2fv(fImageIncrementUni, 1, imageIncrement);
116 fDomain.setData(pdman, bicubicEffect.domain(), proxy,
117 processor.textureSampler(0).samplerState());
118 }
119
GrBicubicEffect(sk_sp<GrTextureProxy> proxy,const SkMatrix & matrix,const GrSamplerState::WrapMode wrapModes[2],GrTextureDomain::Mode modeX,GrTextureDomain::Mode modeY)120 GrBicubicEffect::GrBicubicEffect(sk_sp<GrTextureProxy> proxy,
121 const SkMatrix& matrix,
122 const GrSamplerState::WrapMode wrapModes[2],
123 GrTextureDomain::Mode modeX, GrTextureDomain::Mode modeY)
124 : INHERITED{kGrBicubicEffect_ClassID,
125 ModulateForSamplerOptFlags(proxy->config(),
126 GrTextureDomain::IsDecalSampled(wrapModes, modeX,modeY))}
127 , fCoordTransform(matrix, proxy.get())
128 , fDomain(proxy.get(),
129 GrTextureDomain::MakeTexelDomain(
130 SkIRect::MakeWH(proxy->width(), proxy->height()), modeX, modeY),
131 modeX, modeY)
132 , fTextureSampler(std::move(proxy),
133 GrSamplerState(wrapModes, GrSamplerState::Filter::kNearest)) {
134 this->addCoordTransform(&fCoordTransform);
135 this->setTextureSamplerCnt(1);
136 }
137
GrBicubicEffect(sk_sp<GrTextureProxy> proxy,const SkMatrix & matrix,const SkRect & domain)138 GrBicubicEffect::GrBicubicEffect(sk_sp<GrTextureProxy> proxy,
139 const SkMatrix& matrix,
140 const SkRect& domain)
141 : INHERITED(kGrBicubicEffect_ClassID, ModulateForClampedSamplerOptFlags(proxy->config()))
142 , fCoordTransform(matrix, proxy.get())
143 , fDomain(proxy.get(), domain, GrTextureDomain::kClamp_Mode, GrTextureDomain::kClamp_Mode)
144 , fTextureSampler(std::move(proxy)) {
145 // Make sure the sampler's ctor uses the clamp wrap mode
146 SkASSERT(fTextureSampler.samplerState().wrapModeX() == GrSamplerState::WrapMode::kClamp &&
147 fTextureSampler.samplerState().wrapModeY() == GrSamplerState::WrapMode::kClamp);
148 this->addCoordTransform(&fCoordTransform);
149 this->setTextureSamplerCnt(1);
150 }
151
GrBicubicEffect(const GrBicubicEffect & that)152 GrBicubicEffect::GrBicubicEffect(const GrBicubicEffect& that)
153 : INHERITED(kGrBicubicEffect_ClassID, that.optimizationFlags())
154 , fCoordTransform(that.fCoordTransform)
155 , fDomain(that.fDomain)
156 , fTextureSampler(that.fTextureSampler) {
157 this->addCoordTransform(&fCoordTransform);
158 this->setTextureSamplerCnt(1);
159 }
160
onGetGLSLProcessorKey(const GrShaderCaps & caps,GrProcessorKeyBuilder * b) const161 void GrBicubicEffect::onGetGLSLProcessorKey(const GrShaderCaps& caps,
162 GrProcessorKeyBuilder* b) const {
163 GrGLBicubicEffect::GenKey(*this, caps, b);
164 }
165
onCreateGLSLInstance() const166 GrGLSLFragmentProcessor* GrBicubicEffect::onCreateGLSLInstance() const {
167 return new GrGLBicubicEffect;
168 }
169
onIsEqual(const GrFragmentProcessor & sBase) const170 bool GrBicubicEffect::onIsEqual(const GrFragmentProcessor& sBase) const {
171 const GrBicubicEffect& s = sBase.cast<GrBicubicEffect>();
172 return fDomain == s.fDomain;
173 }
174
175 GR_DEFINE_FRAGMENT_PROCESSOR_TEST(GrBicubicEffect);
176
177 #if GR_TEST_UTILS
TestCreate(GrProcessorTestData * d)178 std::unique_ptr<GrFragmentProcessor> GrBicubicEffect::TestCreate(GrProcessorTestData* d) {
179 int texIdx = d->fRandom->nextBool() ? GrProcessorUnitTest::kSkiaPMTextureIdx
180 : GrProcessorUnitTest::kAlphaTextureIdx;
181 static const GrSamplerState::WrapMode kClampClamp[] = {GrSamplerState::WrapMode::kClamp,
182 GrSamplerState::WrapMode::kClamp};
183 return GrBicubicEffect::Make(d->textureProxy(texIdx), SkMatrix::I(), kClampClamp);
184 }
185 #endif
186
187 //////////////////////////////////////////////////////////////////////////////
188
ShouldUseBicubic(const SkMatrix & matrix,GrSamplerState::Filter * filterMode)189 bool GrBicubicEffect::ShouldUseBicubic(const SkMatrix& matrix, GrSamplerState::Filter* filterMode) {
190 if (matrix.isIdentity()) {
191 *filterMode = GrSamplerState::Filter::kNearest;
192 return false;
193 }
194
195 SkScalar scales[2];
196 if (!matrix.getMinMaxScales(scales) || scales[0] < SK_Scalar1) {
197 // Bicubic doesn't handle arbitrary minimization well, as src texels can be skipped
198 // entirely,
199 *filterMode = GrSamplerState::Filter::kMipMap;
200 return false;
201 }
202 // At this point if scales[1] == SK_Scalar1 then the matrix doesn't do any scaling.
203 if (scales[1] == SK_Scalar1) {
204 if (matrix.rectStaysRect() && SkScalarIsInt(matrix.getTranslateX()) &&
205 SkScalarIsInt(matrix.getTranslateY())) {
206 *filterMode = GrSamplerState::Filter::kNearest;
207 } else {
208 // Use bilerp to handle rotation or fractional translation.
209 *filterMode = GrSamplerState::Filter::kBilerp;
210 }
211 return false;
212 }
213 // When we use the bicubic filtering effect each sample is read from the texture using
214 // nearest neighbor sampling.
215 *filterMode = GrSamplerState::Filter::kNearest;
216 return true;
217 }
218