/src/skia/src/shaders/gradients/SkSweepGradient.cpp
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1 | | /* |
2 | | * Copyright 2012 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 "include/private/SkFloatingPoint.h" |
9 | | #include "src/core/SkRasterPipeline.h" |
10 | | #include "src/core/SkReadBuffer.h" |
11 | | #include "src/core/SkWriteBuffer.h" |
12 | | #include "src/shaders/gradients/SkSweepGradient.h" |
13 | | |
14 | | SkSweepGradient::SkSweepGradient(const SkPoint& center, SkScalar t0, SkScalar t1, |
15 | | const Descriptor& desc) |
16 | | : SkGradientShaderBase(desc, SkMatrix::Translate(-center.x(), -center.y())) |
17 | | , fCenter(center) |
18 | | , fTBias(-t0) |
19 | | , fTScale(1 / (t1 - t0)) |
20 | 3.35k | { |
21 | 3.35k | SkASSERT(t0 < t1); |
22 | 3.35k | } |
23 | | |
24 | 32 | SkShader::GradientType SkSweepGradient::asAGradient(GradientInfo* info) const { |
25 | 32 | if (info) { |
26 | 16 | commonAsAGradient(info); |
27 | 16 | info->fPoint[0] = fCenter; |
28 | 16 | } |
29 | 32 | return kSweep_GradientType; |
30 | 32 | } |
31 | | |
32 | 1 | static std::tuple<SkScalar, SkScalar> angles_from_t_coeff(SkScalar tBias, SkScalar tScale) { |
33 | 1 | return std::make_tuple(-tBias * 360, (sk_ieee_float_divide(1, tScale) - tBias) * 360); |
34 | 1 | } |
35 | | |
36 | 7 | sk_sp<SkFlattenable> SkSweepGradient::CreateProc(SkReadBuffer& buffer) { |
37 | 7 | DescriptorScope desc; |
38 | 7 | if (!desc.unflatten(buffer)) { |
39 | 6 | return nullptr; |
40 | 6 | } |
41 | 1 | const SkPoint center = buffer.readPoint(); |
42 | | |
43 | 1 | const auto tBias = buffer.readScalar(), |
44 | 1 | tScale = buffer.readScalar(); |
45 | 1 | auto [startAngle, endAngle] = angles_from_t_coeff(tBias, tScale); |
46 | | |
47 | 1 | return SkGradientShader::MakeSweep(center.x(), center.y(), desc.fColors, |
48 | 1 | std::move(desc.fColorSpace), desc.fPos, desc.fCount, |
49 | 1 | desc.fTileMode, startAngle, endAngle, |
50 | 1 | desc.fGradFlags, desc.fLocalMatrix); |
51 | 1 | } |
52 | | |
53 | 0 | void SkSweepGradient::flatten(SkWriteBuffer& buffer) const { |
54 | 0 | this->INHERITED::flatten(buffer); |
55 | 0 | buffer.writePoint(fCenter); |
56 | 0 | buffer.writeScalar(fTBias); |
57 | 0 | buffer.writeScalar(fTScale); |
58 | 0 | } |
59 | | |
60 | | void SkSweepGradient::appendGradientStages(SkArenaAlloc* alloc, SkRasterPipeline* p, |
61 | 20.7k | SkRasterPipeline*) const { |
62 | 20.7k | p->append(SkRasterPipeline::xy_to_unit_angle); |
63 | 20.7k | p->append_matrix(alloc, SkMatrix::Scale(fTScale, 1) * SkMatrix::Translate(fTBias, 0)); |
64 | 20.7k | } |
65 | | |
66 | | skvm::F32 SkSweepGradient::transformT(skvm::Builder* p, skvm::Uniforms* uniforms, |
67 | 205 | skvm::Coord coord, skvm::I32* mask) const { |
68 | 205 | skvm::F32 xabs = abs(coord.x), |
69 | 205 | yabs = abs(coord.y), |
70 | 205 | slope = min(xabs, yabs) / max(xabs, yabs); |
71 | 205 | skvm::F32 s = slope * slope; |
72 | | |
73 | | // Use a 7th degree polynomial to approximate atan. |
74 | | // This was generated using sollya.gforge.inria.fr. |
75 | | // A float optimized polynomial was generated using the following command. |
76 | | // P1 = fpminimax((1/(2*Pi))*atan(x),[|1,3,5,7|],[|24...|],[2^(-40),1],relative); |
77 | 205 | skvm::F32 phi = slope * poly(s, -7.0547382347285747528076171875e-3f, |
78 | 205 | +2.476101927459239959716796875e-2f, |
79 | 205 | -5.185396969318389892578125e-2f, |
80 | 205 | +0.15912117063999176025390625f); |
81 | 205 | phi = select( xabs < yabs, (1/4.0f) - phi, phi); |
82 | 205 | phi = select(coord.x < 0.0f, (1/2.0f) - phi, phi); |
83 | 205 | phi = select(coord.y < 0.0f, (1/1.0f) - phi, phi); |
84 | | |
85 | 205 | skvm::F32 t = select(is_NaN(phi), p->splat(0.0f) |
86 | 205 | , phi); |
87 | | |
88 | 205 | if (fTScale != 1.0f || fTBias != 0.0f) { |
89 | 0 | t = t * p->uniformF(uniforms->pushF(fTScale)) |
90 | 0 | + p->uniformF(uniforms->pushF(fTScale*fTBias)); |
91 | 0 | } |
92 | 205 | return t; |
93 | 205 | } |
94 | | |
95 | | ///////////////////////////////////////////////////////////////////// |
96 | | |
97 | | #if SK_SUPPORT_GPU |
98 | | |
99 | | #include "src/gpu/gradients/GrGradientShader.h" |
100 | | |
101 | | std::unique_ptr<GrFragmentProcessor> SkSweepGradient::asFragmentProcessor( |
102 | 1.48k | const GrFPArgs& args) const { |
103 | 1.48k | return GrGradientShader::MakeSweep(*this, args); |
104 | 1.48k | } |
105 | | |
106 | | #endif |