| /* |
| * 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 { |
| public: |
| /** |
| * 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); |
| }; |
| |
| #endif |