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