| |
| /* |
| * 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 GenBaseGradientKey(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(SkRandom* 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->emitUniforms(builder, key); |
| SkString coords; |
| this->setupMatrix(builder, key, &coords); |
| SkString t; |
| t.printf("atan(- %s.y, - %s.x) * 0.1591549430918 + 0.5", coords.c_str(), coords.c_str()); |
| this->emitColor(builder, t.c_str(), key, |
| outputColor, inputColor, samplers); |
| } |
| |
| ///////////////////////////////////////////////////////////////////// |
| |
| 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 |
