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comparison: gfx/skia/trunk/src/effects/gradients/SkSweepGradient.cpp

gfx/skia/trunk/src/effects/gradients/SkSweepGradient.cpp

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1
2 /*
3 * Copyright 2012 Google Inc.
4 *
5 * Use of this source code is governed by a BSD-style license that can be
6 * found in the LICENSE file.
7 */
8
9 #include "SkSweepGradient.h"
10
11 SkSweepGradient::SkSweepGradient(SkScalar cx, SkScalar cy,
12 const Descriptor& desc)
13 : SkGradientShaderBase(desc)
14 , fCenter(SkPoint::Make(cx, cy))
15 {
16 fPtsToUnit.setTranslate(-cx, -cy);
17
18 // overwrite the tilemode to a canonical value (since sweep ignores it)
19 fTileMode = SkShader::kClamp_TileMode;
20 }
21
22 SkShader::BitmapType SkSweepGradient::asABitmap(SkBitmap* bitmap,
23 SkMatrix* matrix, SkShader::TileMode* xy) const {
24 if (bitmap) {
25 this->getGradientTableBitmap(bitmap);
26 }
27 if (matrix) {
28 *matrix = fPtsToUnit;
29 }
30 if (xy) {
31 xy[0] = fTileMode;
32 xy[1] = kClamp_TileMode;
33 }
34 return kSweep_BitmapType;
35 }
36
37 SkShader::GradientType SkSweepGradient::asAGradient(GradientInfo* info) const {
38 if (info) {
39 commonAsAGradient(info);
40 info->fPoint[0] = fCenter;
41 }
42 return kSweep_GradientType;
43 }
44
45 SkSweepGradient::SkSweepGradient(SkReadBuffer& buffer)
46 : INHERITED(buffer),
47 fCenter(buffer.readPoint()) {
48 }
49
50 void SkSweepGradient::flatten(SkWriteBuffer& buffer) const {
51 this->INHERITED::flatten(buffer);
52 buffer.writePoint(fCenter);
53 }
54
55 // returns angle in a circle [0..2PI) -> [0..255]
56 static unsigned SkATan2_255(float y, float x) {
57 // static const float g255Over2PI = 255 / (2 * SK_ScalarPI);
58 static const float g255Over2PI = 40.584510488433314f;
59
60 float result = sk_float_atan2(y, x);
61 if (result < 0) {
62 result += 2 * SK_ScalarPI;
63 }
64 SkASSERT(result >= 0);
65 // since our value is always >= 0, we can cast to int, which is faster than
66 // calling floorf()
67 int ir = (int)(result * g255Over2PI);
68 SkASSERT(ir >= 0 && ir <= 255);
69 return ir;
70 }
71
72 void SkSweepGradient::shadeSpan(int x, int y, SkPMColor* SK_RESTRICT dstC,
73 int count) {
74 SkMatrix::MapXYProc proc = fDstToIndexProc;
75 const SkMatrix& matrix = fDstToIndex;
76 const SkPMColor* SK_RESTRICT cache = this->getCache32();
77 int toggle = init_dither_toggle(x, y);
78 SkPoint srcPt;
79
80 if (fDstToIndexClass != kPerspective_MatrixClass) {
81 proc(matrix, SkIntToScalar(x) + SK_ScalarHalf,
82 SkIntToScalar(y) + SK_ScalarHalf, &srcPt);
83 SkScalar dx, fx = srcPt.fX;
84 SkScalar dy, fy = srcPt.fY;
85
86 if (fDstToIndexClass == kFixedStepInX_MatrixClass) {
87 SkFixed storage[2];
88 (void)matrix.fixedStepInX(SkIntToScalar(y) + SK_ScalarHalf,
89 &storage[0], &storage[1]);
90 dx = SkFixedToScalar(storage[0]);
91 dy = SkFixedToScalar(storage[1]);
92 } else {
93 SkASSERT(fDstToIndexClass == kLinear_MatrixClass);
94 dx = matrix.getScaleX();
95 dy = matrix.getSkewY();
96 }
97
98 for (; count > 0; --count) {
99 *dstC++ = cache[toggle + SkATan2_255(fy, fx)];
100 fx += dx;
101 fy += dy;
102 toggle = next_dither_toggle(toggle);
103 }
104 } else { // perspective case
105 for (int stop = x + count; x < stop; x++) {
106 proc(matrix, SkIntToScalar(x) + SK_ScalarHalf,
107 SkIntToScalar(y) + SK_ScalarHalf, &srcPt);
108 *dstC++ = cache[toggle + SkATan2_255(srcPt.fY, srcPt.fX)];
109 toggle = next_dither_toggle(toggle);
110 }
111 }
112 }
113
114 void SkSweepGradient::shadeSpan16(int x, int y, uint16_t* SK_RESTRICT dstC,
115 int count) {
116 SkMatrix::MapXYProc proc = fDstToIndexProc;
117 const SkMatrix& matrix = fDstToIndex;
118 const uint16_t* SK_RESTRICT cache = this->getCache16();
119 int toggle = init_dither_toggle16(x, y);
120 SkPoint srcPt;
121
122 if (fDstToIndexClass != kPerspective_MatrixClass) {
123 proc(matrix, SkIntToScalar(x) + SK_ScalarHalf,
124 SkIntToScalar(y) + SK_ScalarHalf, &srcPt);
125 SkScalar dx, fx = srcPt.fX;
126 SkScalar dy, fy = srcPt.fY;
127
128 if (fDstToIndexClass == kFixedStepInX_MatrixClass) {
129 SkFixed storage[2];
130 (void)matrix.fixedStepInX(SkIntToScalar(y) + SK_ScalarHalf,
131 &storage[0], &storage[1]);
132 dx = SkFixedToScalar(storage[0]);
133 dy = SkFixedToScalar(storage[1]);
134 } else {
135 SkASSERT(fDstToIndexClass == kLinear_MatrixClass);
136 dx = matrix.getScaleX();
137 dy = matrix.getSkewY();
138 }
139
140 for (; count > 0; --count) {
141 int index = SkATan2_255(fy, fx) >> (8 - kCache16Bits);
142 *dstC++ = cache[toggle + index];
143 toggle = next_dither_toggle16(toggle);
144 fx += dx;
145 fy += dy;
146 }
147 } else { // perspective case
148 for (int stop = x + count; x < stop; x++) {
149 proc(matrix, SkIntToScalar(x) + SK_ScalarHalf,
150 SkIntToScalar(y) + SK_ScalarHalf, &srcPt);
151
152 int index = SkATan2_255(srcPt.fY, srcPt.fX);
153 index >>= (8 - kCache16Bits);
154 *dstC++ = cache[toggle + index];
155 toggle = next_dither_toggle16(toggle);
156 }
157 }
158 }
159
160 /////////////////////////////////////////////////////////////////////
161
162 #if SK_SUPPORT_GPU
163
164 #include "GrTBackendEffectFactory.h"
165
166 class GrGLSweepGradient : public GrGLGradientEffect {
167 public:
168
169 GrGLSweepGradient(const GrBackendEffectFactory& factory,
170 const GrDrawEffect&) : INHERITED (factory) { }
171 virtual ~GrGLSweepGradient() { }
172
173 virtual void emitCode(GrGLShaderBuilder*,
174 const GrDrawEffect&,
175 EffectKey,
176 const char* outputColor,
177 const char* inputColor,
178 const TransformedCoordsArray&,
179 const TextureSamplerArray&) SK_OVERRIDE;
180
181 static EffectKey GenKey(const GrDrawEffect& drawEffect, const GrGLCaps&) {
182 return GenBaseGradientKey(drawEffect);
183 }
184
185 private:
186
187 typedef GrGLGradientEffect INHERITED;
188
189 };
190
191 /////////////////////////////////////////////////////////////////////
192
193 class GrSweepGradient : public GrGradientEffect {
194 public:
195 static GrEffectRef* Create(GrContext* ctx,
196 const SkSweepGradient& shader,
197 const SkMatrix& matrix) {
198 AutoEffectUnref effect(SkNEW_ARGS(GrSweepGradient, (ctx, shader, matrix)));
199 return CreateEffectRef(effect);
200 }
201 virtual ~GrSweepGradient() { }
202
203 static const char* Name() { return "Sweep Gradient"; }
204 virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE {
205 return GrTBackendEffectFactory<GrSweepGradient>::getInstance();
206 }
207
208 typedef GrGLSweepGradient GLEffect;
209
210 private:
211 GrSweepGradient(GrContext* ctx,
212 const SkSweepGradient& shader,
213 const SkMatrix& matrix)
214 : INHERITED(ctx, shader, matrix, SkShader::kClamp_TileMode) { }
215 GR_DECLARE_EFFECT_TEST;
216
217 typedef GrGradientEffect INHERITED;
218 };
219
220 /////////////////////////////////////////////////////////////////////
221
222 GR_DEFINE_EFFECT_TEST(GrSweepGradient);
223
224 GrEffectRef* GrSweepGradient::TestCreate(SkRandom* random,
225 GrContext* context,
226 const GrDrawTargetCaps&,
227 GrTexture**) {
228 SkPoint center = {random->nextUScalar1(), random->nextUScalar1()};
229
230 SkColor colors[kMaxRandomGradientColors];
231 SkScalar stopsArray[kMaxRandomGradientColors];
232 SkScalar* stops = stopsArray;
233 SkShader::TileMode tmIgnored;
234 int colorCount = RandomGradientParams(random, colors, &stops, &tmIgnored);
235 SkAutoTUnref<SkShader> shader(SkGradientShader::CreateSweep(center.fX, center.fY,
236 colors, stops, colorCount));
237 SkPaint paint;
238 return shader->asNewEffect(context, paint);
239 }
240
241 /////////////////////////////////////////////////////////////////////
242
243 void GrGLSweepGradient::emitCode(GrGLShaderBuilder* builder,
244 const GrDrawEffect&,
245 EffectKey key,
246 const char* outputColor,
247 const char* inputColor,
248 const TransformedCoordsArray& coords,
249 const TextureSamplerArray& samplers) {
250 this->emitUniforms(builder, key);
251 SkString coords2D = builder->ensureFSCoords2D(coords, 0);
252 const GrGLContextInfo ctxInfo = builder->ctxInfo();
253 SkString t;
254 // 0.1591549430918 is 1/(2*pi), used since atan returns values [-pi, pi]
255 // On Intel GPU there is an issue where it reads the second arguement to atan "- %s.x" as an int
256 // thus must us -1.0 * %s.x to work correctly
257 if (kIntel_GrGLVendor != ctxInfo.vendor()){
258 t.printf("atan(- %s.y, - %s.x) * 0.1591549430918 + 0.5",
259 coords2D.c_str(), coords2D.c_str());
260 } else {
261 t.printf("atan(- %s.y, -1.0 * %s.x) * 0.1591549430918 + 0.5",
262 coords2D.c_str(), coords2D.c_str());
263 }
264 this->emitColor(builder, t.c_str(), key,
265 outputColor, inputColor, samplers);
266 }
267
268 /////////////////////////////////////////////////////////////////////
269
270 GrEffectRef* SkSweepGradient::asNewEffect(GrContext* context, const SkPaint&) const {
271 SkMatrix matrix;
272 if (!this->getLocalMatrix().invert(&matrix)) {
273 return NULL;
274 }
275 matrix.postConcat(fPtsToUnit);
276 return GrSweepGradient::Create(context, *this, matrix);
277 }
278
279 #else
280
281 GrEffectRef* SkSweepGradient::asNewEffect(GrContext*, const SkPaint&) const {
282 SkDEBUGFAIL("Should not call in GPU-less build");
283 return NULL;
284 }
285
286 #endif
287
288 #ifndef SK_IGNORE_TO_STRING
289 void SkSweepGradient::toString(SkString* str) const {
290 str->append("SkSweepGradient: (");
291
292 str->append("center: (");
293 str->appendScalar(fCenter.fX);
294 str->append(", ");
295 str->appendScalar(fCenter.fY);
296 str->append(") ");
297
298 this->INHERITED::toString(str);
299
300 str->append(")");
301 }
302 #endif

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