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Diffstat (limited to 'effects/gradients/SkSweepGradient.cpp')
| -rw-r--r-- | effects/gradients/SkSweepGradient.cpp | 517 |
1 files changed, 517 insertions, 0 deletions
diff --git a/effects/gradients/SkSweepGradient.cpp b/effects/gradients/SkSweepGradient.cpp new file mode 100644 index 00000000..f975a188 --- /dev/null +++ b/effects/gradients/SkSweepGradient.cpp @@ -0,0 +1,517 @@ + +/* + * Copyright 2012 Google Inc. + * + * Use of this source code is governed by a BSD-style license that can be + * found in the LICENSE file. + */ + +#include "SkSweepGradient.h" + +SkSweepGradient::SkSweepGradient(SkScalar cx, SkScalar cy, + const Descriptor& desc) + : SkGradientShaderBase(desc) + , fCenter(SkPoint::Make(cx, cy)) +{ + fPtsToUnit.setTranslate(-cx, -cy); + + // overwrite the tilemode to a canonical value (since sweep ignores it) + fTileMode = SkShader::kClamp_TileMode; +} + +SkShader::BitmapType SkSweepGradient::asABitmap(SkBitmap* bitmap, + SkMatrix* matrix, SkShader::TileMode* xy) const { + if (bitmap) { + this->getGradientTableBitmap(bitmap); + } + if (matrix) { + *matrix = fPtsToUnit; + } + if (xy) { + xy[0] = fTileMode; + xy[1] = kClamp_TileMode; + } + return kSweep_BitmapType; +} + +SkShader::GradientType SkSweepGradient::asAGradient(GradientInfo* info) const { + if (info) { + commonAsAGradient(info); + info->fPoint[0] = fCenter; + } + return kSweep_GradientType; +} + +SkSweepGradient::SkSweepGradient(SkFlattenableReadBuffer& buffer) + : INHERITED(buffer), + fCenter(buffer.readPoint()) { +} + +void SkSweepGradient::flatten(SkFlattenableWriteBuffer& buffer) const { + this->INHERITED::flatten(buffer); + buffer.writePoint(fCenter); +} + +#ifndef SK_SCALAR_IS_FLOAT +#ifdef COMPUTE_SWEEP_TABLE +#define PI 3.14159265 +static bool gSweepTableReady; +static uint8_t gSweepTable[65]; + +/* Our table stores precomputed values for atan: [0...1] -> [0..PI/4] + We scale the results to [0..32] +*/ +static const uint8_t* build_sweep_table() { + if (!gSweepTableReady) { + const int N = 65; + const double DENOM = N - 1; + + for (int i = 0; i < N; i++) + { + double arg = i / DENOM; + double v = atan(arg); + int iv = (int)round(v * DENOM * 2 / PI); +// printf("[%d] atan(%g) = %g %d\n", i, arg, v, iv); + printf("%d, ", iv); + gSweepTable[i] = iv; + } + gSweepTableReady = true; + } + return gSweepTable; +} +#else +static const uint8_t gSweepTable[] = { + 0, 1, 1, 2, 3, 3, 4, 4, 5, 6, 6, 7, 8, 8, 9, 9, + 10, 11, 11, 12, 12, 13, 13, 14, 15, 15, 16, 16, 17, 17, 18, 18, + 19, 19, 20, 20, 21, 21, 22, 22, 23, 23, 24, 24, 25, 25, 25, 26, + 26, 27, 27, 27, 28, 28, 29, 29, 29, 30, 30, 30, 31, 31, 31, 32, + 32 +}; +static const uint8_t* build_sweep_table() { return gSweepTable; } +#endif +#endif + +// divide numer/denom, with a bias of 6bits. Assumes numer <= denom +// and denom != 0. Since our table is 6bits big (+1), this is a nice fit. +// Same as (but faster than) SkFixedDiv(numer, denom) >> 10 + +//unsigned div_64(int numer, int denom); +#ifndef SK_SCALAR_IS_FLOAT +static unsigned div_64(int numer, int denom) { + SkASSERT(numer <= denom); + SkASSERT(numer > 0); + SkASSERT(denom > 0); + + int nbits = SkCLZ(numer); + int dbits = SkCLZ(denom); + int bits = 6 - nbits + dbits; + SkASSERT(bits <= 6); + + if (bits < 0) { // detect underflow + return 0; + } + + denom <<= dbits - 1; + numer <<= nbits - 1; + + unsigned result = 0; + + // do the first one + if ((numer -= denom) >= 0) { + result = 1; + } else { + numer += denom; + } + + // Now fall into our switch statement if there are more bits to compute + if (bits > 0) { + // make room for the rest of the answer bits + result <<= bits; + switch (bits) { + case 6: + if ((numer = (numer << 1) - denom) >= 0) + result |= 32; + else + numer += denom; + case 5: + if ((numer = (numer << 1) - denom) >= 0) + result |= 16; + else + numer += denom; + case 4: + if ((numer = (numer << 1) - denom) >= 0) + result |= 8; + else + numer += denom; + case 3: + if ((numer = (numer << 1) - denom) >= 0) + result |= 4; + else + numer += denom; + case 2: + if ((numer = (numer << 1) - denom) >= 0) + result |= 2; + else + numer += denom; + case 1: + default: // not strictly need, but makes GCC make better ARM code + if ((numer = (numer << 1) - denom) >= 0) + result |= 1; + else + numer += denom; + } + } + return result; +} +#endif + +// Given x,y in the first quadrant, return 0..63 for the angle [0..90] +#ifndef SK_SCALAR_IS_FLOAT +static unsigned atan_0_90(SkFixed y, SkFixed x) { +#ifdef SK_DEBUG + { + static bool gOnce; + if (!gOnce) { + gOnce = true; + SkASSERT(div_64(55, 55) == 64); + SkASSERT(div_64(128, 256) == 32); + SkASSERT(div_64(2326528, 4685824) == 31); + SkASSERT(div_64(753664, 5210112) == 9); + SkASSERT(div_64(229376, 4882432) == 3); + SkASSERT(div_64(2, 64) == 2); + SkASSERT(div_64(1, 64) == 1); + // test that we handle underflow correctly + SkASSERT(div_64(12345, 0x54321234) == 0); + } + } +#endif + + SkASSERT(y > 0 && x > 0); + const uint8_t* table = build_sweep_table(); + + unsigned result; + bool swap = (x < y); + if (swap) { + // first part of the atan(v) = PI/2 - atan(1/v) identity + // since our div_64 and table want v <= 1, where v = y/x + SkTSwap<SkFixed>(x, y); + } + + result = div_64(y, x); + +#ifdef SK_DEBUG + { + unsigned result2 = SkDivBits(y, x, 6); + SkASSERT(result2 == result || + (result == 1 && result2 == 0)); + } +#endif + + SkASSERT(result < SK_ARRAY_COUNT(gSweepTable)); + result = table[result]; + + if (swap) { + // complete the atan(v) = PI/2 - atan(1/v) identity + result = 64 - result; + // pin to 63 + result -= result >> 6; + } + + SkASSERT(result <= 63); + return result; +} +#endif + +// returns angle in a circle [0..2PI) -> [0..255] +#ifdef SK_SCALAR_IS_FLOAT +static unsigned SkATan2_255(float y, float x) { + // static const float g255Over2PI = 255 / (2 * SK_ScalarPI); + static const float g255Over2PI = 40.584510488433314f; + + float result = sk_float_atan2(y, x); + if (result < 0) { + result += 2 * SK_ScalarPI; + } + SkASSERT(result >= 0); + // since our value is always >= 0, we can cast to int, which is faster than + // calling floorf() + int ir = (int)(result * g255Over2PI); + SkASSERT(ir >= 0 && ir <= 255); + return ir; +} +#else +static unsigned SkATan2_255(SkFixed y, SkFixed x) { + if (x == 0) { + if (y == 0) { + return 0; + } + return y < 0 ? 192 : 64; + } + if (y == 0) { + return x < 0 ? 128 : 0; + } + + /* Find the right quadrant for x,y + Since atan_0_90 only handles the first quadrant, we rotate x,y + appropriately before calling it, and then add the right amount + to account for the real quadrant. + quadrant 0 : add 0 | x > 0 && y > 0 + quadrant 1 : add 64 (90 degrees) | x < 0 && y > 0 + quadrant 2 : add 128 (180 degrees) | x < 0 && y < 0 + quadrant 3 : add 192 (270 degrees) | x > 0 && y < 0 + + map x<0 to (1 << 6) + map y<0 to (3 << 6) + add = map_x ^ map_y + */ + int xsign = x >> 31; + int ysign = y >> 31; + int add = ((-xsign) ^ (ysign & 3)) << 6; + +#ifdef SK_DEBUG + if (0 == add) + SkASSERT(x > 0 && y > 0); + else if (64 == add) + SkASSERT(x < 0 && y > 0); + else if (128 == add) + SkASSERT(x < 0 && y < 0); + else if (192 == add) + SkASSERT(x > 0 && y < 0); + else + SkDEBUGFAIL("bad value for add"); +#endif + + /* This ^ trick makes x, y positive, and the swap<> handles quadrants + where we need to rotate x,y by 90 or -90 + */ + x = (x ^ xsign) - xsign; + y = (y ^ ysign) - ysign; + if (add & 64) { // quads 1 or 3 need to swap x,y + SkTSwap<SkFixed>(x, y); + } + + unsigned result = add + atan_0_90(y, x); + SkASSERT(result < 256); + return result; +} +#endif + +void SkSweepGradient::shadeSpan(int x, int y, SkPMColor* SK_RESTRICT dstC, + int count) { + SkMatrix::MapXYProc proc = fDstToIndexProc; + const SkMatrix& matrix = fDstToIndex; + const SkPMColor* SK_RESTRICT cache = this->getCache32(); + int toggle = init_dither_toggle(x, y); + SkPoint srcPt; + + if (fDstToIndexClass != kPerspective_MatrixClass) { + proc(matrix, SkIntToScalar(x) + SK_ScalarHalf, + SkIntToScalar(y) + SK_ScalarHalf, &srcPt); + SkScalar dx, fx = srcPt.fX; + SkScalar dy, fy = srcPt.fY; + + if (fDstToIndexClass == kFixedStepInX_MatrixClass) { + SkFixed storage[2]; + (void)matrix.fixedStepInX(SkIntToScalar(y) + SK_ScalarHalf, + &storage[0], &storage[1]); + dx = SkFixedToScalar(storage[0]); + dy = SkFixedToScalar(storage[1]); + } else { + SkASSERT(fDstToIndexClass == kLinear_MatrixClass); + dx = matrix.getScaleX(); + dy = matrix.getSkewY(); + } + + for (; count > 0; --count) { + *dstC++ = cache[toggle + SkATan2_255(fy, fx)]; + fx += dx; + fy += dy; + toggle = next_dither_toggle(toggle); + } + } else { // perspective case + for (int stop = x + count; x < stop; x++) { + proc(matrix, SkIntToScalar(x) + SK_ScalarHalf, + SkIntToScalar(y) + SK_ScalarHalf, &srcPt); + *dstC++ = cache[toggle + SkATan2_255(srcPt.fY, srcPt.fX)]; + toggle = next_dither_toggle(toggle); + } + } +} + +void SkSweepGradient::shadeSpan16(int x, int y, uint16_t* SK_RESTRICT dstC, + int count) { + SkMatrix::MapXYProc proc = fDstToIndexProc; + const SkMatrix& matrix = fDstToIndex; + const uint16_t* SK_RESTRICT cache = this->getCache16(); + int toggle = init_dither_toggle16(x, y); + SkPoint srcPt; + + if (fDstToIndexClass != kPerspective_MatrixClass) { + proc(matrix, SkIntToScalar(x) + SK_ScalarHalf, + SkIntToScalar(y) + SK_ScalarHalf, &srcPt); + SkScalar dx, fx = srcPt.fX; + SkScalar dy, fy = srcPt.fY; + + if (fDstToIndexClass == kFixedStepInX_MatrixClass) { + SkFixed storage[2]; + (void)matrix.fixedStepInX(SkIntToScalar(y) + SK_ScalarHalf, + &storage[0], &storage[1]); + dx = SkFixedToScalar(storage[0]); + dy = SkFixedToScalar(storage[1]); + } else { + SkASSERT(fDstToIndexClass == kLinear_MatrixClass); + dx = matrix.getScaleX(); + dy = matrix.getSkewY(); + } + + for (; count > 0; --count) { + int index = SkATan2_255(fy, fx) >> (8 - kCache16Bits); + *dstC++ = cache[toggle + index]; + toggle = next_dither_toggle16(toggle); + fx += dx; + fy += dy; + } + } else { // perspective case + for (int stop = x + count; x < stop; x++) { + proc(matrix, SkIntToScalar(x) + SK_ScalarHalf, + SkIntToScalar(y) + SK_ScalarHalf, &srcPt); + + int index = SkATan2_255(srcPt.fY, srcPt.fX); + index >>= (8 - kCache16Bits); + *dstC++ = cache[toggle + index]; + toggle = next_dither_toggle16(toggle); + } + } +} + +///////////////////////////////////////////////////////////////////// + +#if SK_SUPPORT_GPU + +#include "GrTBackendEffectFactory.h" + +class GrGLSweepGradient : public GrGLGradientEffect { +public: + + GrGLSweepGradient(const GrBackendEffectFactory& factory, + const GrDrawEffect&) : INHERITED (factory) { } + virtual ~GrGLSweepGradient() { } + + virtual void emitCode(GrGLShaderBuilder*, + const GrDrawEffect&, + EffectKey, + const char* outputColor, + const char* inputColor, + const TextureSamplerArray&) SK_OVERRIDE; + + static EffectKey GenKey(const GrDrawEffect& drawEffect, const GrGLCaps&) { + return GenMatrixKey(drawEffect); + } + +private: + + typedef GrGLGradientEffect INHERITED; + +}; + +///////////////////////////////////////////////////////////////////// + +class GrSweepGradient : public GrGradientEffect { +public: + static GrEffectRef* Create(GrContext* ctx, + const SkSweepGradient& shader, + const SkMatrix& matrix) { + AutoEffectUnref effect(SkNEW_ARGS(GrSweepGradient, (ctx, shader, matrix))); + return CreateEffectRef(effect); + } + virtual ~GrSweepGradient() { } + + static const char* Name() { return "Sweep Gradient"; } + virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE { + return GrTBackendEffectFactory<GrSweepGradient>::getInstance(); + } + + typedef GrGLSweepGradient GLEffect; + +private: + GrSweepGradient(GrContext* ctx, + const SkSweepGradient& shader, + const SkMatrix& matrix) + : INHERITED(ctx, shader, matrix, SkShader::kClamp_TileMode) { } + GR_DECLARE_EFFECT_TEST; + + typedef GrGradientEffect INHERITED; +}; + +///////////////////////////////////////////////////////////////////// + +GR_DEFINE_EFFECT_TEST(GrSweepGradient); + +GrEffectRef* GrSweepGradient::TestCreate(SkMWCRandom* random, + GrContext* context, + const GrDrawTargetCaps&, + GrTexture**) { + SkPoint center = {random->nextUScalar1(), random->nextUScalar1()}; + + SkColor colors[kMaxRandomGradientColors]; + SkScalar stopsArray[kMaxRandomGradientColors]; + SkScalar* stops = stopsArray; + SkShader::TileMode tmIgnored; + int colorCount = RandomGradientParams(random, colors, &stops, &tmIgnored); + SkAutoTUnref<SkShader> shader(SkGradientShader::CreateSweep(center.fX, center.fY, + colors, stops, colorCount)); + SkPaint paint; + return shader->asNewEffect(context, paint); +} + +///////////////////////////////////////////////////////////////////// + +void GrGLSweepGradient::emitCode(GrGLShaderBuilder* builder, + const GrDrawEffect&, + EffectKey key, + const char* outputColor, + const char* inputColor, + const TextureSamplerArray& samplers) { + this->emitYCoordUniform(builder); + const char* coords; + this->setupMatrix(builder, key, &coords); + SkString t; + t.printf("atan(- %s.y, - %s.x) * 0.1591549430918 + 0.5", coords, coords); + this->emitColorLookup(builder, t.c_str(), outputColor, inputColor, samplers[0]); +} + +///////////////////////////////////////////////////////////////////// + +GrEffectRef* SkSweepGradient::asNewEffect(GrContext* context, const SkPaint&) const { + SkMatrix matrix; + if (!this->getLocalMatrix().invert(&matrix)) { + return NULL; + } + matrix.postConcat(fPtsToUnit); + return GrSweepGradient::Create(context, *this, matrix); +} + +#else + +GrEffectRef* SkSweepGradient::asNewEffect(GrContext*, const SkPaint&) const { + SkDEBUGFAIL("Should not call in GPU-less build"); + return NULL; +} + +#endif + +#ifdef SK_DEVELOPER +void SkSweepGradient::toString(SkString* str) const { + str->append("SkSweepGradient: ("); + + str->append("center: ("); + str->appendScalar(fCenter.fX); + str->append(", "); + str->appendScalar(fCenter.fY); + str->append(") "); + + this->INHERITED::toString(str); + + str->append(")"); +} +#endif |