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// Copyright 2025 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef THIRD_PARTY_BLINK_RENDERER_CORE_STYLE_SUPERELLIPSE_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_STYLE_SUPERELLIPSE_H_
#include <cmath>
#include <limits>
#include "third_party/blink/renderer/platform/wtf/math_extras.h"
namespace blink {
// Represents a superellipse, as defined in
// https://drafts.csswg.org/css-borders-4/#funcdef-superellipse
class Superellipse {
public:
static constexpr float kHighCurvatureThreshold = 16;
// https://drafts.csswg.org/css-borders-4/#valdef-corner-shape-value-bevel
static constexpr Superellipse Bevel() { return Superellipse(0); }
// https://drafts.csswg.org/css-borders-4/#valdef-corner-shape-value-notch
static constexpr Superellipse Notch() {
return Superellipse(std::numeric_limits<double>::lowest());
}
// https://drafts.csswg.org/css-borders-4/#valdef-corner-shape-value-round
static constexpr Superellipse Round() { return Superellipse(1); }
// https://drafts.csswg.org/css-borders-4/#valdef-corner-shape-value-scoop
static constexpr Superellipse Scoop() { return Superellipse(-1); }
// https://drafts.csswg.org/css-borders-4/#valdef-corner-shape-value-squircle
static constexpr Superellipse Squircle() { return Superellipse(2); }
// https://drafts.csswg.org/css-borders-4/#valdef-corner-shape-value-square
static constexpr Superellipse Square() {
return Superellipse(std::numeric_limits<double>::max());
}
// Very high curvatures are counted as straight as there would be no visual
// effect. "Degenerate" means that the corner should be considered to have a
// zero-size rather than consider its size and curvature.
constexpr bool IsDegenerate() const {
return param_ >= kHighCurvatureThreshold;
}
constexpr bool IsFullyConcave() const {
return param_ <= -kHighCurvatureThreshold;
}
constexpr bool IsConvex() const { return param_ >= 0; }
constexpr explicit Superellipse(double param) : param_(param) {}
// https://drafts.csswg.org/css-borders-4/#superellipse-param
constexpr double Parameter() const { return param_; }
constexpr double Exponent() const {
return std::pow(2, ClampTo<float>(param_, -kHighCurvatureThreshold,
kHighCurvatureThreshold));
}
bool operator==(const Superellipse& other) const = default;
private:
double param_;
};
} // namespace blink
#endif // THIRD_PARTY_BLINK_RENDERER_CORE_STYLE_SUPERELLIPSE_H_
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