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 "SkColorSpaceXformer.h"
9 #include "SkFloatingPoint.h"
10 #include "SkRasterPipeline.h"
11 #include "SkReadBuffer.h"
12 #include "SkSweepGradient.h"
13 #include "SkWriteBuffer.h"
14 
15 SkSweepGradient::SkSweepGradient(const SkPoint& center, SkScalar t0, SkScalar t1,
16                                  const Descriptor& desc)
17     : SkGradientShaderBase(desc, SkMatrix::MakeTrans(-center.x(), -center.y()))
18     , fCenter(center)
19     , fTBias(-t0)
20     , fTScale(1 / (t1 - t0))
21 {
22     SkASSERT(t0 < t1);
23 }
24 
25 SkShader::GradientType SkSweepGradient::asAGradient(GradientInfo* info) const {
26     if (info) {
27         commonAsAGradient(info);
28         info->fPoint[0] = fCenter;
29     }
30     return kSweep_GradientType;
31 }
32 
33 static std::tuple<SkScalar, SkScalar> angles_from_t_coeff(SkScalar tBias, SkScalar tScale) {
34     return std::make_tuple(-tBias * 360, (sk_ieee_float_divide(1, tScale) - tBias) * 360);
35 }
36 
37 sk_sp<SkFlattenable> SkSweepGradient::CreateProc(SkReadBuffer& buffer) {
38     DescriptorScope desc;
39     if (!desc.unflatten(buffer)) {
40         return nullptr;
41     }
42     const SkPoint center = buffer.readPoint();
43 
44     SkScalar startAngle = 0,
45                endAngle = 360;
46     if (!buffer.isVersionLT(SkReadBuffer::kTileInfoInSweepGradient_Version)) {
47         const auto tBias  = buffer.readScalar(),
48                    tScale = buffer.readScalar();
49         std::tie(startAngle, endAngle) = angles_from_t_coeff(tBias, tScale);
50     }
51 
52     return SkGradientShader::MakeSweep(center.x(), center.y(), desc.fColors,
53                                        std::move(desc.fColorSpace), desc.fPos, desc.fCount,
54                                        desc.fTileMode, startAngle, endAngle,
55                                        desc.fGradFlags, desc.fLocalMatrix);
56 }
57 
58 void SkSweepGradient::flatten(SkWriteBuffer& buffer) const {
59     this->INHERITED::flatten(buffer);
60     buffer.writePoint(fCenter);
61     buffer.writeScalar(fTBias);
62     buffer.writeScalar(fTScale);
63 }
64 
65 sk_sp<SkShader> SkSweepGradient::onMakeColorSpace(SkColorSpaceXformer* xformer) const {
66     const AutoXformColors xformedColors(*this, xformer);
67 
68     SkScalar startAngle, endAngle;
69     std::tie(startAngle, endAngle) = angles_from_t_coeff(fTBias, fTScale);
70 
71     return SkGradientShader::MakeSweep(fCenter.fX, fCenter.fY, xformedColors.fColors.get(),
72                                        fOrigPos, fColorCount, fTileMode, startAngle, endAngle,
73                                        fGradFlags, &this->getLocalMatrix());
74 }
75 
76 void SkSweepGradient::appendGradientStages(SkArenaAlloc* alloc, SkRasterPipeline* p,
77                                            SkRasterPipeline*) const {
78     p->append(SkRasterPipeline::xy_to_unit_angle);
79     p->append_matrix(alloc, SkMatrix::Concat(SkMatrix::MakeScale(fTScale, 1),
80                                              SkMatrix::MakeTrans(fTBias , 0)));
81 }
82 
83 /////////////////////////////////////////////////////////////////////
84 
85 #if SK_SUPPORT_GPU
86 
87 #include "gradients/GrGradientShader.h"
88 
89 std::unique_ptr<GrFragmentProcessor> SkSweepGradient::asFragmentProcessor(
90         const GrFPArgs& args) const {
91     return GrGradientShader::MakeSweep(*this, args);
92 }
93 
94 #endif
95