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- /*
- * Copyright 2012 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
- #ifndef SkTwoPointConicalGradient_DEFINED
- #define SkTwoPointConicalGradient_DEFINED
- #include "src/shaders/gradients/SkGradientShaderPriv.h"
- class SkTwoPointConicalGradient final : public SkGradientShaderBase {
- public:
- // See https://skia.org/dev/design/conical for what focal data means and how our shader works.
- // We make it public so the GPU shader can also use it.
- struct FocalData {
- SkScalar fR1; // r1 after mapping focal point to (0, 0)
- SkScalar fFocalX; // f
- bool fIsSwapped; // whether we swapped r0, r1
- // The input r0, r1 are the radii when we map centers to {(0, 0), (1, 0)}.
- // We'll post concat matrix with our transformation matrix that maps focal point to (0, 0).
- // Returns true if the set succeeded
- bool set(SkScalar r0, SkScalar r1, SkMatrix* matrix);
- // Whether the focal point (0, 0) is on the end circle with center (1, 0) and radius r1. If
- // this is true, it's as if an aircraft is flying at Mach 1 and all circles (soundwaves)
- // will go through the focal point (aircraft). In our previous implementations, this was
- // known as the edge case where the inside circle touches the outside circle (on the focal
- // point). If we were to solve for t bruteforcely using a quadratic equation, this case
- // implies that the quadratic equation degenerates to a linear equation.
- bool isFocalOnCircle() const { return SkScalarNearlyZero(1 - fR1); }
- bool isSwapped() const { return fIsSwapped; }
- bool isWellBehaved() const { return !this->isFocalOnCircle() && fR1 > 1; }
- bool isNativelyFocal() const { return SkScalarNearlyZero(fFocalX); }
- };
- enum class Type {
- kRadial,
- kStrip,
- kFocal
- };
- static sk_sp<SkShader> Create(const SkPoint& start, SkScalar startRadius,
- const SkPoint& end, SkScalar endRadius,
- const Descriptor&);
- SkShader::GradientType asAGradient(GradientInfo* info) const override;
- #if SK_SUPPORT_GPU
- std::unique_ptr<GrFragmentProcessor> asFragmentProcessor(const GrFPArgs&) const override;
- #endif
- bool isOpaque() const override;
- SkScalar getCenterX1() const { return SkPoint::Distance(fCenter1, fCenter2); }
- SkScalar getStartRadius() const { return fRadius1; }
- SkScalar getDiffRadius() const { return fRadius2 - fRadius1; }
- const SkPoint& getStartCenter() const { return fCenter1; }
- const SkPoint& getEndCenter() const { return fCenter2; }
- SkScalar getEndRadius() const { return fRadius2; }
- Type getType() const { return fType; }
- const FocalData& getFocalData() const { return fFocalData; }
- protected:
- void flatten(SkWriteBuffer& buffer) const override;
- void appendGradientStages(SkArenaAlloc* alloc, SkRasterPipeline* tPipeline,
- SkRasterPipeline* postPipeline) const override;
- private:
- SK_FLATTENABLE_HOOKS(SkTwoPointConicalGradient)
- SkTwoPointConicalGradient(const SkPoint& c0, SkScalar r0,
- const SkPoint& c1, SkScalar r1,
- const Descriptor&, Type, const SkMatrix&, const FocalData&);
- SkPoint fCenter1;
- SkPoint fCenter2;
- SkScalar fRadius1;
- SkScalar fRadius2;
- Type fType;
- FocalData fFocalData;
- friend class SkGradientShader;
- typedef SkGradientShaderBase INHERITED;
- };
- #endif
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