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 "GrProxyMove.h"
11 #include "GrTextureProxy.h"
12 #include "glsl/GrGLSLColorSpaceXformHelper.h"
13 #include "glsl/GrGLSLFragmentShaderBuilder.h"
14 #include "glsl/GrGLSLProgramDataManager.h"
15 #include "glsl/GrGLSLUniformHandler.h"
16 #include "../private/GrGLSL.h"
17
18 class GrGLBicubicEffect : public GrGLSLFragmentProcessor {
19 public:
20 void emitCode(EmitArgs&) override;
21
GenKey(const GrProcessor & effect,const GrShaderCaps &,GrProcessorKeyBuilder * b)22 static inline void GenKey(const GrProcessor& effect, const GrShaderCaps&,
23 GrProcessorKeyBuilder* b) {
24 const GrBicubicEffect& bicubicEffect = effect.cast<GrBicubicEffect>();
25 b->add32(GrTextureDomain::GLDomain::DomainKey(bicubicEffect.domain()));
26 b->add32(GrColorSpaceXform::XformKey(bicubicEffect.colorSpaceXform()));
27 }
28
29 protected:
30 void onSetData(const GrGLSLProgramDataManager&, const GrProcessor&) override;
31
32 private:
33 typedef GrGLSLProgramDataManager::UniformHandle UniformHandle;
34
35 UniformHandle fImageIncrementUni;
36 GrGLSLColorSpaceXformHelper fColorSpaceHelper;
37 GrTextureDomain::GLDomain fDomain;
38
39 typedef GrGLSLFragmentProcessor INHERITED;
40 };
41
emitCode(EmitArgs & args)42 void GrGLBicubicEffect::emitCode(EmitArgs& args) {
43 const GrBicubicEffect& bicubicEffect = args.fFp.cast<GrBicubicEffect>();
44
45 GrGLSLUniformHandler* uniformHandler = args.fUniformHandler;
46 fImageIncrementUni = uniformHandler->addUniform(kFragment_GrShaderFlag,
47 kVec2f_GrSLType, kDefault_GrSLPrecision,
48 "ImageIncrement");
49
50 const char* imgInc = uniformHandler->getUniformCStr(fImageIncrementUni);
51
52 fColorSpaceHelper.emitCode(uniformHandler, bicubicEffect.colorSpaceXform());
53
54 GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
55 SkString coords2D = fragBuilder->ensureCoords2D(args.fTransformedCoords[0]);
56
57 /*
58 * Filter weights come from Don Mitchell & Arun Netravali's 'Reconstruction Filters in Computer
59 * Graphics', ACM SIGGRAPH Computer Graphics 22, 4 (Aug. 1988).
60 * ACM DL: http://dl.acm.org/citation.cfm?id=378514
61 * Free : http://www.cs.utexas.edu/users/fussell/courses/cs384g/lectures/mitchell/Mitchell.pdf
62 *
63 * The authors define a family of cubic filters with two free parameters (B and C):
64 *
65 * { (12 - 9B - 6C)|x|^3 + (-18 + 12B + 6C)|x|^2 + (6 - 2B) if |x| < 1
66 * k(x) = 1/6 { (-B - 6C)|x|^3 + (6B + 30C)|x|^2 + (-12B - 48C)|x| + (8B + 24C) if 1 <= |x| < 2
67 * { 0 otherwise
68 *
69 * Various well-known cubic splines can be generated, and the authors select (1/3, 1/3) as their
70 * favorite overall spline - this is now commonly known as the Mitchell filter, and is the
71 * source of the specific weights below.
72 *
73 * This is GLSL, so the matrix is column-major (transposed from standard matrix notation).
74 */
75 fragBuilder->codeAppend("mat4 kMitchellCoefficients = mat4("
76 " 1.0 / 18.0, 16.0 / 18.0, 1.0 / 18.0, 0.0 / 18.0,"
77 "-9.0 / 18.0, 0.0 / 18.0, 9.0 / 18.0, 0.0 / 18.0,"
78 "15.0 / 18.0, -36.0 / 18.0, 27.0 / 18.0, -6.0 / 18.0,"
79 "-7.0 / 18.0, 21.0 / 18.0, -21.0 / 18.0, 7.0 / 18.0);");
80 fragBuilder->codeAppendf("vec2 coord = %s - %s * vec2(0.5);", coords2D.c_str(), imgInc);
81 // We unnormalize the coord in order to determine our fractional offset (f) within the texel
82 // We then snap coord to a texel center and renormalize. The snap prevents cases where the
83 // starting coords are near a texel boundary and accumulations of imgInc would cause us to skip/
84 // double hit a texel.
85 fragBuilder->codeAppendf("coord /= %s;", imgInc);
86 fragBuilder->codeAppend("vec2 f = fract(coord);");
87 fragBuilder->codeAppendf("coord = (coord - f + vec2(0.5)) * %s;", imgInc);
88 fragBuilder->codeAppend("vec4 wx = kMitchellCoefficients * vec4(1.0, f.x, f.x * f.x, f.x * f.x * f.x);");
89 fragBuilder->codeAppend("vec4 wy = kMitchellCoefficients * vec4(1.0, f.y, f.y * f.y, f.y * f.y * f.y);");
90 fragBuilder->codeAppend("vec4 rowColors[4];");
91 for (int y = 0; y < 4; ++y) {
92 for (int x = 0; x < 4; ++x) {
93 SkString coord;
94 coord.printf("coord + %s * vec2(%d, %d)", imgInc, x - 1, y - 1);
95 SkString sampleVar;
96 sampleVar.printf("rowColors[%d]", x);
97 fDomain.sampleTexture(fragBuilder,
98 args.fUniformHandler,
99 args.fShaderCaps,
100 bicubicEffect.domain(),
101 sampleVar.c_str(),
102 coord,
103 args.fTexSamplers[0]);
104 }
105 fragBuilder->codeAppendf(
106 "vec4 s%d = wx.x * rowColors[0] + wx.y * rowColors[1] + wx.z * rowColors[2] + wx.w * rowColors[3];",
107 y);
108 }
109 SkString bicubicColor("(wy.x * s0 + wy.y * s1 + wy.z * s2 + wy.w * s3)");
110 if (fColorSpaceHelper.isValid()) {
111 SkString xformedColor;
112 fragBuilder->appendColorGamutXform(&xformedColor, bicubicColor.c_str(), &fColorSpaceHelper);
113 bicubicColor.swap(xformedColor);
114 }
115 fragBuilder->codeAppendf("%s = %s;",
116 args.fOutputColor, (GrGLSLExpr4(bicubicColor.c_str()) *
117 GrGLSLExpr4(args.fInputColor)).c_str());
118 }
119
onSetData(const GrGLSLProgramDataManager & pdman,const GrProcessor & processor)120 void GrGLBicubicEffect::onSetData(const GrGLSLProgramDataManager& pdman,
121 const GrProcessor& processor) {
122 const GrBicubicEffect& bicubicEffect = processor.cast<GrBicubicEffect>();
123 GrTexture* texture = processor.textureSampler(0).texture();
124 float imageIncrement[2];
125 imageIncrement[0] = 1.0f / texture->width();
126 imageIncrement[1] = 1.0f / texture->height();
127 pdman.set2fv(fImageIncrementUni, 1, imageIncrement);
128 fDomain.setData(pdman, bicubicEffect.domain(), texture);
129 if (SkToBool(bicubicEffect.colorSpaceXform())) {
130 fColorSpaceHelper.setData(pdman, bicubicEffect.colorSpaceXform());
131 }
132 }
133
GrBicubicEffect(GrResourceProvider * resourceProvider,sk_sp<GrTextureProxy> proxy,sk_sp<GrColorSpaceXform> colorSpaceXform,const SkMatrix & matrix,const SkShader::TileMode tileModes[2])134 GrBicubicEffect::GrBicubicEffect(GrResourceProvider* resourceProvider, sk_sp<GrTextureProxy> proxy,
135 sk_sp<GrColorSpaceXform> colorSpaceXform,
136 const SkMatrix &matrix,
137 const SkShader::TileMode tileModes[2])
138 : INHERITED{resourceProvider,
139 ModulationFlags(proxy->config()),
140 GR_PROXY_MOVE(proxy),
141 std::move(colorSpaceXform),
142 matrix,
143 GrSamplerParams(tileModes, GrSamplerParams::kNone_FilterMode)}
144 , fDomain(GrTextureDomain::IgnoredDomain()) {
145 this->initClassID<GrBicubicEffect>();
146 }
147
GrBicubicEffect(GrResourceProvider * resourceProvider,sk_sp<GrTextureProxy> proxy,sk_sp<GrColorSpaceXform> colorSpaceXform,const SkMatrix & matrix,const SkRect & domain)148 GrBicubicEffect::GrBicubicEffect(GrResourceProvider* resourceProvider, sk_sp<GrTextureProxy> proxy,
149 sk_sp<GrColorSpaceXform> colorSpaceXform,
150 const SkMatrix &matrix,
151 const SkRect& domain)
152 : INHERITED(resourceProvider, ModulationFlags(proxy->config()), proxy,
153 std::move(colorSpaceXform), matrix,
154 GrSamplerParams(SkShader::kClamp_TileMode, GrSamplerParams::kNone_FilterMode))
155 , fDomain(proxy.get(), domain, GrTextureDomain::kClamp_Mode) {
156 this->initClassID<GrBicubicEffect>();
157 }
158
~GrBicubicEffect()159 GrBicubicEffect::~GrBicubicEffect() {
160 }
161
onGetGLSLProcessorKey(const GrShaderCaps & caps,GrProcessorKeyBuilder * b) const162 void GrBicubicEffect::onGetGLSLProcessorKey(const GrShaderCaps& caps,
163 GrProcessorKeyBuilder* b) const {
164 GrGLBicubicEffect::GenKey(*this, caps, b);
165 }
166
onCreateGLSLInstance() const167 GrGLSLFragmentProcessor* GrBicubicEffect::onCreateGLSLInstance() const {
168 return new GrGLBicubicEffect;
169 }
170
onIsEqual(const GrFragmentProcessor & sBase) const171 bool GrBicubicEffect::onIsEqual(const GrFragmentProcessor& sBase) const {
172 const GrBicubicEffect& s = sBase.cast<GrBicubicEffect>();
173 return fDomain == s.fDomain;
174 }
175
176 GR_DEFINE_FRAGMENT_PROCESSOR_TEST(GrBicubicEffect);
177
178 #if GR_TEST_UTILS
TestCreate(GrProcessorTestData * d)179 sk_sp<GrFragmentProcessor> GrBicubicEffect::TestCreate(GrProcessorTestData* d) {
180 int texIdx = d->fRandom->nextBool() ? GrProcessorUnitTest::kSkiaPMTextureIdx
181 : GrProcessorUnitTest::kAlphaTextureIdx;
182 sk_sp<GrColorSpaceXform> colorSpaceXform = GrTest::TestColorXform(d->fRandom);
183 static const SkShader::TileMode kClampClamp[] =
184 { SkShader::kClamp_TileMode, SkShader::kClamp_TileMode };
185 return GrBicubicEffect::Make(d->resourceProvider(),
186 d->textureProxy(texIdx), std::move(colorSpaceXform),
187 SkMatrix::I(), kClampClamp);
188 }
189 #endif
190
191 //////////////////////////////////////////////////////////////////////////////
192
ShouldUseBicubic(const SkMatrix & matrix,GrSamplerParams::FilterMode * filterMode)193 bool GrBicubicEffect::ShouldUseBicubic(const SkMatrix& matrix,
194 GrSamplerParams::FilterMode* filterMode) {
195 if (matrix.isIdentity()) {
196 *filterMode = GrSamplerParams::kNone_FilterMode;
197 return false;
198 }
199
200 SkScalar scales[2];
201 if (!matrix.getMinMaxScales(scales) || scales[0] < SK_Scalar1) {
202 // Bicubic doesn't handle arbitrary minimization well, as src texels can be skipped
203 // entirely,
204 *filterMode = GrSamplerParams::kMipMap_FilterMode;
205 return false;
206 }
207 // At this point if scales[1] == SK_Scalar1 then the matrix doesn't do any scaling.
208 if (scales[1] == SK_Scalar1) {
209 if (matrix.rectStaysRect() && SkScalarIsInt(matrix.getTranslateX()) &&
210 SkScalarIsInt(matrix.getTranslateY())) {
211 *filterMode = GrSamplerParams::kNone_FilterMode;
212 } else {
213 // Use bilerp to handle rotation or fractional translation.
214 *filterMode = GrSamplerParams::kBilerp_FilterMode;
215 }
216 return false;
217 }
218 // When we use the bicubic filtering effect each sample is read from the texture using
219 // nearest neighbor sampling.
220 *filterMode = GrSamplerParams::kNone_FilterMode;
221 return true;
222 }
223