SkSweepGradient.cpp revision fc28bd5db465dd98fb8d6295de90064a7170e6c5
154e7afa84d945f9137f9372ecde432f9e1a702fcGreg Clayton 254e7afa84d945f9137f9372ecde432f9e1a702fcGreg Clayton/* 354e7afa84d945f9137f9372ecde432f9e1a702fcGreg Clayton * Copyright 2012 Google Inc. 454e7afa84d945f9137f9372ecde432f9e1a702fcGreg Clayton * 554e7afa84d945f9137f9372ecde432f9e1a702fcGreg Clayton * Use of this source code is governed by a BSD-style license that can be 654e7afa84d945f9137f9372ecde432f9e1a702fcGreg Clayton * found in the LICENSE file. 754e7afa84d945f9137f9372ecde432f9e1a702fcGreg Clayton */ 854e7afa84d945f9137f9372ecde432f9e1a702fcGreg Clayton 954e7afa84d945f9137f9372ecde432f9e1a702fcGreg Clayton#include "SkSweepGradient.h" 1054e7afa84d945f9137f9372ecde432f9e1a702fcGreg Clayton 1154e7afa84d945f9137f9372ecde432f9e1a702fcGreg ClaytonSkSweepGradient::SkSweepGradient(SkScalar cx, SkScalar cy, const SkColor colors[], 1254e7afa84d945f9137f9372ecde432f9e1a702fcGreg Clayton const SkScalar pos[], int count, SkUnitMapper* mapper) 1354e7afa84d945f9137f9372ecde432f9e1a702fcGreg Clayton: SkGradientShaderBase(colors, pos, count, SkShader::kClamp_TileMode, mapper), 1454e7afa84d945f9137f9372ecde432f9e1a702fcGreg Clayton fCenter(SkPoint::Make(cx, cy)) 1554e7afa84d945f9137f9372ecde432f9e1a702fcGreg Clayton{ 1654e7afa84d945f9137f9372ecde432f9e1a702fcGreg Clayton fPtsToUnit.setTranslate(-cx, -cy); 17eca14c7b52fdd83705787ca354758d7cd93b8894Peter Collingbourne} 1854e7afa84d945f9137f9372ecde432f9e1a702fcGreg Clayton 19b9db9d5bb01963774f28540dbe2c5a11f586ff29Daniel MaleaSkShader::BitmapType SkSweepGradient::asABitmap(SkBitmap* bitmap, 20b9db9d5bb01963774f28540dbe2c5a11f586ff29Daniel Malea SkMatrix* matrix, SkShader::TileMode* xy) const { 21b9db9d5bb01963774f28540dbe2c5a11f586ff29Daniel Malea if (bitmap) { 22b9db9d5bb01963774f28540dbe2c5a11f586ff29Daniel Malea this->getGradientTableBitmap(bitmap); 23b9db9d5bb01963774f28540dbe2c5a11f586ff29Daniel Malea } 24b9db9d5bb01963774f28540dbe2c5a11f586ff29Daniel Malea if (matrix) { 25b9db9d5bb01963774f28540dbe2c5a11f586ff29Daniel Malea *matrix = fPtsToUnit; 264bb4f30fef9281506baf536a254cac17ae68bd73Filipe Cabecinhas } 274bb4f30fef9281506baf536a254cac17ae68bd73Filipe Cabecinhas if (xy) { 284bb4f30fef9281506baf536a254cac17ae68bd73Filipe Cabecinhas xy[0] = fTileMode; 29f2b0fef6c754acd4f6a3d7cc5cc5f3ad9be98be7Filipe Cabecinhas xy[1] = kClamp_TileMode; 30dc3e063595c1b87729242b83baa0ea92a5987704Johnny Chen } 31f2b0fef6c754acd4f6a3d7cc5cc5f3ad9be98be7Filipe Cabecinhas return kSweep_BitmapType; 32f2b0fef6c754acd4f6a3d7cc5cc5f3ad9be98be7Filipe Cabecinhas} 33f2b0fef6c754acd4f6a3d7cc5cc5f3ad9be98be7Filipe Cabecinhas 34d4c21f0e25545061dcbaef597531a4796dbe15efCharles DavisSkShader::GradientType SkSweepGradient::asAGradient(GradientInfo* info) const { 35f2b0fef6c754acd4f6a3d7cc5cc5f3ad9be98be7Filipe Cabecinhas if (info) { 36f2b0fef6c754acd4f6a3d7cc5cc5f3ad9be98be7Filipe Cabecinhas commonAsAGradient(info); 37d4c21f0e25545061dcbaef597531a4796dbe15efCharles Davis info->fPoint[0] = fCenter; 38f2b0fef6c754acd4f6a3d7cc5cc5f3ad9be98be7Filipe Cabecinhas } 39d4c21f0e25545061dcbaef597531a4796dbe15efCharles Davis return kSweep_GradientType; 40f2b0fef6c754acd4f6a3d7cc5cc5f3ad9be98be7Filipe Cabecinhas} 41eca14c7b52fdd83705787ca354758d7cd93b8894Peter Collingbourne 42eca14c7b52fdd83705787ca354758d7cd93b8894Peter CollingbourneSkSweepGradient::SkSweepGradient(SkFlattenableReadBuffer& buffer) 43f2b0fef6c754acd4f6a3d7cc5cc5f3ad9be98be7Filipe Cabecinhas : INHERITED(buffer), 44 fCenter(buffer.readPoint()) { 45} 46 47void SkSweepGradient::flatten(SkFlattenableWriteBuffer& buffer) const { 48 this->INHERITED::flatten(buffer); 49 buffer.writePoint(fCenter); 50} 51 52#ifndef SK_SCALAR_IS_FLOAT 53#ifdef COMPUTE_SWEEP_TABLE 54#define PI 3.14159265 55static bool gSweepTableReady; 56static uint8_t gSweepTable[65]; 57 58/* Our table stores precomputed values for atan: [0...1] -> [0..PI/4] 59 We scale the results to [0..32] 60*/ 61static const uint8_t* build_sweep_table() { 62 if (!gSweepTableReady) { 63 const int N = 65; 64 const double DENOM = N - 1; 65 66 for (int i = 0; i < N; i++) 67 { 68 double arg = i / DENOM; 69 double v = atan(arg); 70 int iv = (int)round(v * DENOM * 2 / PI); 71// printf("[%d] atan(%g) = %g %d\n", i, arg, v, iv); 72 printf("%d, ", iv); 73 gSweepTable[i] = iv; 74 } 75 gSweepTableReady = true; 76 } 77 return gSweepTable; 78} 79#else 80static const uint8_t gSweepTable[] = { 81 0, 1, 1, 2, 3, 3, 4, 4, 5, 6, 6, 7, 8, 8, 9, 9, 82 10, 11, 11, 12, 12, 13, 13, 14, 15, 15, 16, 16, 17, 17, 18, 18, 83 19, 19, 20, 20, 21, 21, 22, 22, 23, 23, 24, 24, 25, 25, 25, 26, 84 26, 27, 27, 27, 28, 28, 29, 29, 29, 30, 30, 30, 31, 31, 31, 32, 85 32 86}; 87static const uint8_t* build_sweep_table() { return gSweepTable; } 88#endif 89#endif 90 91// divide numer/denom, with a bias of 6bits. Assumes numer <= denom 92// and denom != 0. Since our table is 6bits big (+1), this is a nice fit. 93// Same as (but faster than) SkFixedDiv(numer, denom) >> 10 94 95//unsigned div_64(int numer, int denom); 96#ifndef SK_SCALAR_IS_FLOAT 97static unsigned div_64(int numer, int denom) { 98 SkASSERT(numer <= denom); 99 SkASSERT(numer > 0); 100 SkASSERT(denom > 0); 101 102 int nbits = SkCLZ(numer); 103 int dbits = SkCLZ(denom); 104 int bits = 6 - nbits + dbits; 105 SkASSERT(bits <= 6); 106 107 if (bits < 0) { // detect underflow 108 return 0; 109 } 110 111 denom <<= dbits - 1; 112 numer <<= nbits - 1; 113 114 unsigned result = 0; 115 116 // do the first one 117 if ((numer -= denom) >= 0) { 118 result = 1; 119 } else { 120 numer += denom; 121 } 122 123 // Now fall into our switch statement if there are more bits to compute 124 if (bits > 0) { 125 // make room for the rest of the answer bits 126 result <<= bits; 127 switch (bits) { 128 case 6: 129 if ((numer = (numer << 1) - denom) >= 0) 130 result |= 32; 131 else 132 numer += denom; 133 case 5: 134 if ((numer = (numer << 1) - denom) >= 0) 135 result |= 16; 136 else 137 numer += denom; 138 case 4: 139 if ((numer = (numer << 1) - denom) >= 0) 140 result |= 8; 141 else 142 numer += denom; 143 case 3: 144 if ((numer = (numer << 1) - denom) >= 0) 145 result |= 4; 146 else 147 numer += denom; 148 case 2: 149 if ((numer = (numer << 1) - denom) >= 0) 150 result |= 2; 151 else 152 numer += denom; 153 case 1: 154 default: // not strictly need, but makes GCC make better ARM code 155 if ((numer = (numer << 1) - denom) >= 0) 156 result |= 1; 157 else 158 numer += denom; 159 } 160 } 161 return result; 162} 163#endif 164 165// Given x,y in the first quadrant, return 0..63 for the angle [0..90] 166#ifndef SK_SCALAR_IS_FLOAT 167static unsigned atan_0_90(SkFixed y, SkFixed x) { 168#ifdef SK_DEBUG 169 { 170 static bool gOnce; 171 if (!gOnce) { 172 gOnce = true; 173 SkASSERT(div_64(55, 55) == 64); 174 SkASSERT(div_64(128, 256) == 32); 175 SkASSERT(div_64(2326528, 4685824) == 31); 176 SkASSERT(div_64(753664, 5210112) == 9); 177 SkASSERT(div_64(229376, 4882432) == 3); 178 SkASSERT(div_64(2, 64) == 2); 179 SkASSERT(div_64(1, 64) == 1); 180 // test that we handle underflow correctly 181 SkASSERT(div_64(12345, 0x54321234) == 0); 182 } 183 } 184#endif 185 186 SkASSERT(y > 0 && x > 0); 187 const uint8_t* table = build_sweep_table(); 188 189 unsigned result; 190 bool swap = (x < y); 191 if (swap) { 192 // first part of the atan(v) = PI/2 - atan(1/v) identity 193 // since our div_64 and table want v <= 1, where v = y/x 194 SkTSwap<SkFixed>(x, y); 195 } 196 197 result = div_64(y, x); 198 199#ifdef SK_DEBUG 200 { 201 unsigned result2 = SkDivBits(y, x, 6); 202 SkASSERT(result2 == result || 203 (result == 1 && result2 == 0)); 204 } 205#endif 206 207 SkASSERT(result < SK_ARRAY_COUNT(gSweepTable)); 208 result = table[result]; 209 210 if (swap) { 211 // complete the atan(v) = PI/2 - atan(1/v) identity 212 result = 64 - result; 213 // pin to 63 214 result -= result >> 6; 215 } 216 217 SkASSERT(result <= 63); 218 return result; 219} 220#endif 221 222// returns angle in a circle [0..2PI) -> [0..255] 223#ifdef SK_SCALAR_IS_FLOAT 224static unsigned SkATan2_255(float y, float x) { 225 // static const float g255Over2PI = 255 / (2 * SK_ScalarPI); 226 static const float g255Over2PI = 40.584510488433314f; 227 228 float result = sk_float_atan2(y, x); 229 if (result < 0) { 230 result += 2 * SK_ScalarPI; 231 } 232 SkASSERT(result >= 0); 233 // since our value is always >= 0, we can cast to int, which is faster than 234 // calling floorf() 235 int ir = (int)(result * g255Over2PI); 236 SkASSERT(ir >= 0 && ir <= 255); 237 return ir; 238} 239#else 240static unsigned SkATan2_255(SkFixed y, SkFixed x) { 241 if (x == 0) { 242 if (y == 0) { 243 return 0; 244 } 245 return y < 0 ? 192 : 64; 246 } 247 if (y == 0) { 248 return x < 0 ? 128 : 0; 249 } 250 251 /* Find the right quadrant for x,y 252 Since atan_0_90 only handles the first quadrant, we rotate x,y 253 appropriately before calling it, and then add the right amount 254 to account for the real quadrant. 255 quadrant 0 : add 0 | x > 0 && y > 0 256 quadrant 1 : add 64 (90 degrees) | x < 0 && y > 0 257 quadrant 2 : add 128 (180 degrees) | x < 0 && y < 0 258 quadrant 3 : add 192 (270 degrees) | x > 0 && y < 0 259 260 map x<0 to (1 << 6) 261 map y<0 to (3 << 6) 262 add = map_x ^ map_y 263 */ 264 int xsign = x >> 31; 265 int ysign = y >> 31; 266 int add = ((-xsign) ^ (ysign & 3)) << 6; 267 268#ifdef SK_DEBUG 269 if (0 == add) 270 SkASSERT(x > 0 && y > 0); 271 else if (64 == add) 272 SkASSERT(x < 0 && y > 0); 273 else if (128 == add) 274 SkASSERT(x < 0 && y < 0); 275 else if (192 == add) 276 SkASSERT(x > 0 && y < 0); 277 else 278 SkDEBUGFAIL("bad value for add"); 279#endif 280 281 /* This ^ trick makes x, y positive, and the swap<> handles quadrants 282 where we need to rotate x,y by 90 or -90 283 */ 284 x = (x ^ xsign) - xsign; 285 y = (y ^ ysign) - ysign; 286 if (add & 64) { // quads 1 or 3 need to swap x,y 287 SkTSwap<SkFixed>(x, y); 288 } 289 290 unsigned result = add + atan_0_90(y, x); 291 SkASSERT(result < 256); 292 return result; 293} 294#endif 295 296void SkSweepGradient::shadeSpan(int x, int y, SkPMColor* SK_RESTRICT dstC, 297 int count) { 298 SkMatrix::MapXYProc proc = fDstToIndexProc; 299 const SkMatrix& matrix = fDstToIndex; 300 const SkPMColor* SK_RESTRICT cache = this->getCache32(); 301 int toggle = init_dither_toggle(x, y); 302 SkPoint srcPt; 303 304 if (fDstToIndexClass != kPerspective_MatrixClass) { 305 proc(matrix, SkIntToScalar(x) + SK_ScalarHalf, 306 SkIntToScalar(y) + SK_ScalarHalf, &srcPt); 307 SkScalar dx, fx = srcPt.fX; 308 SkScalar dy, fy = srcPt.fY; 309 310 if (fDstToIndexClass == kFixedStepInX_MatrixClass) { 311 SkFixed storage[2]; 312 (void)matrix.fixedStepInX(SkIntToScalar(y) + SK_ScalarHalf, 313 &storage[0], &storage[1]); 314 dx = SkFixedToScalar(storage[0]); 315 dy = SkFixedToScalar(storage[1]); 316 } else { 317 SkASSERT(fDstToIndexClass == kLinear_MatrixClass); 318 dx = matrix.getScaleX(); 319 dy = matrix.getSkewY(); 320 } 321 322 for (; count > 0; --count) { 323 *dstC++ = cache[toggle + SkATan2_255(fy, fx)]; 324 fx += dx; 325 fy += dy; 326 toggle = next_dither_toggle(toggle); 327 } 328 } else { // perspective case 329 for (int stop = x + count; x < stop; x++) { 330 proc(matrix, SkIntToScalar(x) + SK_ScalarHalf, 331 SkIntToScalar(y) + SK_ScalarHalf, &srcPt); 332 *dstC++ = cache[toggle + SkATan2_255(srcPt.fY, srcPt.fX)]; 333 toggle = next_dither_toggle(toggle); 334 } 335 } 336} 337 338void SkSweepGradient::shadeSpan16(int x, int y, uint16_t* SK_RESTRICT dstC, 339 int count) { 340 SkMatrix::MapXYProc proc = fDstToIndexProc; 341 const SkMatrix& matrix = fDstToIndex; 342 const uint16_t* SK_RESTRICT cache = this->getCache16(); 343 int toggle = init_dither_toggle16(x, y); 344 SkPoint srcPt; 345 346 if (fDstToIndexClass != kPerspective_MatrixClass) { 347 proc(matrix, SkIntToScalar(x) + SK_ScalarHalf, 348 SkIntToScalar(y) + SK_ScalarHalf, &srcPt); 349 SkScalar dx, fx = srcPt.fX; 350 SkScalar dy, fy = srcPt.fY; 351 352 if (fDstToIndexClass == kFixedStepInX_MatrixClass) { 353 SkFixed storage[2]; 354 (void)matrix.fixedStepInX(SkIntToScalar(y) + SK_ScalarHalf, 355 &storage[0], &storage[1]); 356 dx = SkFixedToScalar(storage[0]); 357 dy = SkFixedToScalar(storage[1]); 358 } else { 359 SkASSERT(fDstToIndexClass == kLinear_MatrixClass); 360 dx = matrix.getScaleX(); 361 dy = matrix.getSkewY(); 362 } 363 364 for (; count > 0; --count) { 365 int index = SkATan2_255(fy, fx) >> (8 - kCache16Bits); 366 *dstC++ = cache[toggle + index]; 367 toggle = next_dither_toggle16(toggle); 368 fx += dx; 369 fy += dy; 370 } 371 } else { // perspective case 372 for (int stop = x + count; x < stop; x++) { 373 proc(matrix, SkIntToScalar(x) + SK_ScalarHalf, 374 SkIntToScalar(y) + SK_ScalarHalf, &srcPt); 375 376 int index = SkATan2_255(srcPt.fY, srcPt.fX); 377 index >>= (8 - kCache16Bits); 378 *dstC++ = cache[toggle + index]; 379 toggle = next_dither_toggle16(toggle); 380 } 381 } 382} 383 384///////////////////////////////////////////////////////////////////// 385 386#if SK_SUPPORT_GPU 387 388#include "GrTBackendEffectFactory.h" 389 390class GrGLSweepGradient : public GrGLGradientEffect { 391public: 392 393 GrGLSweepGradient(const GrBackendEffectFactory& factory, 394 const GrEffectRef&) : INHERITED (factory) { } 395 virtual ~GrGLSweepGradient() { } 396 397 virtual void emitCode(GrGLShaderBuilder*, 398 const GrEffectStage&, 399 EffectKey, 400 const char* vertexCoords, 401 const char* outputColor, 402 const char* inputColor, 403 const TextureSamplerArray&) SK_OVERRIDE; 404 405 static EffectKey GenKey(const GrEffectStage& stage, const GrGLCaps&) { 406 return GenMatrixKey(stage); 407 } 408 409private: 410 411 typedef GrGLGradientEffect INHERITED; 412 413}; 414 415///////////////////////////////////////////////////////////////////// 416 417class GrSweepGradient : public GrGradientEffect { 418public: 419 static GrEffectRef* Create(GrContext* ctx, 420 const SkSweepGradient& shader, 421 const SkMatrix& matrix) { 422 AutoEffectUnref effect(SkNEW_ARGS(GrSweepGradient, (ctx, shader, matrix))); 423 return CreateEffectRef(effect); 424 } 425 virtual ~GrSweepGradient() { } 426 427 static const char* Name() { return "Sweep Gradient"; } 428 virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE { 429 return GrTBackendEffectFactory<GrSweepGradient>::getInstance(); 430 } 431 432 typedef GrGLSweepGradient GLEffect; 433 434private: 435 GrSweepGradient(GrContext* ctx, 436 const SkSweepGradient& shader, 437 const SkMatrix& matrix) 438 : INHERITED(ctx, shader, matrix, SkShader::kClamp_TileMode) { } 439 GR_DECLARE_EFFECT_TEST; 440 441 typedef GrGradientEffect INHERITED; 442}; 443 444///////////////////////////////////////////////////////////////////// 445 446GR_DEFINE_EFFECT_TEST(GrSweepGradient); 447 448GrEffectRef* GrSweepGradient::TestCreate(SkMWCRandom* random, 449 GrContext* context, 450 GrTexture**) { 451 SkPoint center = {random->nextUScalar1(), random->nextUScalar1()}; 452 453 SkColor colors[kMaxRandomGradientColors]; 454 SkScalar stopsArray[kMaxRandomGradientColors]; 455 SkScalar* stops = stopsArray; 456 SkShader::TileMode tmIgnored; 457 int colorCount = RandomGradientParams(random, colors, &stops, &tmIgnored); 458 SkAutoTUnref<SkShader> shader(SkGradientShader::CreateSweep(center.fX, center.fY, 459 colors, stops, colorCount)); 460 SkPaint paint; 461 return shader->asNewEffect(context, paint); 462} 463 464///////////////////////////////////////////////////////////////////// 465 466void GrGLSweepGradient::emitCode(GrGLShaderBuilder* builder, 467 const GrEffectStage& stage, 468 EffectKey key, 469 const char* vertexCoords, 470 const char* outputColor, 471 const char* inputColor, 472 const TextureSamplerArray& samplers) { 473 this->emitYCoordUniform(builder); 474 const char* coords; 475 this->setupMatrix(builder, key, vertexCoords, &coords); 476 SkString t; 477 t.printf("atan(- %s.y, - %s.x) * 0.1591549430918 + 0.5", coords, coords); 478 this->emitColorLookup(builder, t.c_str(), outputColor, inputColor, samplers[0]); 479} 480 481///////////////////////////////////////////////////////////////////// 482 483GrEffectRef* SkSweepGradient::asNewEffect(GrContext* context, const SkPaint&) const { 484 SkMatrix matrix; 485 if (!this->getLocalMatrix().invert(&matrix)) { 486 return NULL; 487 } 488 matrix.postConcat(fPtsToUnit); 489 return GrSweepGradient::Create(context, *this, matrix); 490} 491 492#else 493 494GrEffectRef* SkSweepGradient::asNewEffect(GrContext*, const SkPaint&) const { 495 SkDEBUGFAIL("Should not call in GPU-less build"); 496 return NULL; 497} 498 499#endif 500 501#ifdef SK_DEVELOPER 502void SkSweepGradient::toString(SkString* str) const { 503 str->append("SkSweepGradient: ("); 504 505 str->append("center: ("); 506 str->appendScalar(fCenter.fX); 507 str->append(", "); 508 str->appendScalar(fCenter.fY); 509 str->append(") "); 510 511 this->INHERITED::toString(str); 512 513 str->append(")"); 514} 515#endif 516