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* Copyright 2023 Google LLC
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#ifndef SkBezierCurves_DEFINED
#define SkBezierCurves_DEFINED
#include <array>
* Utilities for dealing with cubic Bézier curves. These have a start XY
* point, an end XY point, and two control XY points in between. They take
* a parameter t which is between 0 and 1 (inclusive) which is used to
* interpolate between the start and end points, via a route dictated by
* the control points, and return a new XY point.
* We store a Bézier curve as an array of 8 floats or doubles, where
* the even indices are the X coordinates, and the odd indices are the Y
* coordinates.
class SkBezierCubic {
* Splits the provided Bézier curve at the location t, resulting in two
* Bézier curves that share a point (the end point from curve 1
* and the start point from curve 2 are the same).
* t must be in the interval [0, 1].
* The provided twoCurves array will be filled such that indices
* 0-7 are the first curve (representing the interval [0, t]), and
* indices 6-13 are the second curve (representing [t, 1]).
static void Subdivide(const double curve[8], double t,
double twoCurves[14]);
* Converts the provided Bézier curve into the the equivalent cubic
* f(t) = A*t^3 + B*t^2 + C*t + D
* where f(t) will represent Y coordinates over time if yValues is
* true and the X coordinates if yValues is false.
* In effect, this turns the control points into an actual line, representing
* the x or y values.
static std::array<double, 4> ConvertToPolynomial(const double curve[8], bool yValues);