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// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef UI_GFX_GEOMETRY_LINEAR_GRADIENT_H_
#define UI_GFX_GEOMETRY_LINEAR_GRADIENT_H_
#include <stdint.h>
#include <array>
#include <cstddef>
#include <cstdint>
#include <string>
#include "base/component_export.h"
namespace gfx {
class AxisTransform2d;
class Transform;
// A class that defines a linear gradient mask.
// Up to 6 steps are supported.
//
// ex. Horizontal linear gradient that starts in the middle.
// LinearGradient gradient(0);
// gradient.AddStep(20, 0);
// gradient.AddStep(30, 255);
// gradient.AddStep(70, 255);
// gradient.AddStep(80, 0);
class COMPONENT_EXPORT(GEOMETRY_SKIA) LinearGradient {
public:
struct Step {
// Fraction that defines a position in diagonal, from 0 to 1.
float fraction = 0;
// Alpha, from 0 to 255.
uint8_t alpha = 0;
friend bool operator==(const Step&, const Step&) = default;
};
static LinearGradient& GetEmpty();
static constexpr size_t kMaxStepSize = 8;
using StepArray = std::array<Step, kMaxStepSize>;
LinearGradient();
explicit LinearGradient(int16_t angle);
LinearGradient(const LinearGradient& copy);
LinearGradient& operator=(const LinearGradient& gradient_mask) = default;
bool IsEmpty() const { return !step_count_; }
// Add a new step. Adding more than 6 results in DCHECK or ignored.
void AddStep(float fraction, uint8_t alpha);
// Get step information.
const StepArray& steps() const { return steps_; }
StepArray& steps() { return steps_; }
size_t step_count() const { return step_count_; }
// Gets/Sets an angle (in degrees).
int16_t angle() const { return angle_; }
void set_angle(int16_t degree) { angle_ = degree; }
// Reverse the steps.
void ReverseSteps();
// Transform the angle.
void ApplyTransform(const Transform& transform);
void ApplyTransform(const AxisTransform2d& transform);
std::string ToString() const;
friend bool operator==(const LinearGradient&,
const LinearGradient&) = default;
private:
// angle in degrees.
int16_t angle_ = 0;
size_t step_count_ = 0;
StepArray steps_;
};
} // namespace gfx
#endif // UI_GFX_GEOMETRY_LINEAR_GRADIENT_H_
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