/**
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* n角星（n>3）
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* @module zrender/graphic/shape/Star
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*/
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import Path, { PathProps } from '../Path';
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const PI = Math.PI;
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const cos = Math.cos;
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const sin = Math.sin;
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export class StarShape {
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cx = 0
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cy = 0
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n = 3
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r0: number
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r = 0
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}
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export interface StarProps extends PathProps {
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shape?: Partial<StarShape>
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}
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class Star extends Path<StarProps> {
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shape: StarShape
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constructor(opts?: StarProps) {
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super(opts);
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}
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getDefaultShape() {
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return new StarShape();
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}
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buildPath(ctx: CanvasRenderingContext2D, shape: StarShape) {
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const n = shape.n;
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if (!n || n < 2) {
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return;
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}
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const x = shape.cx;
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const y = shape.cy;
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const r = shape.r;
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let r0 = shape.r0;
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// 如果未指定内部顶点外接圆半径，则自动计算
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if (r0 == null) {
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r0 = n > 4
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// 相隔的外部顶点的连线的交点，
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// 被取为内部交点，以此计算r0
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? r * cos(2 * PI / n) / cos(PI / n)
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// 二三四角星的特殊处理
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: r / 3;
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}
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const dStep = PI / n;
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let deg = -PI / 2;
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const xStart = x + r * cos(deg);
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const yStart = y + r * sin(deg);
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deg += dStep;
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// 记录边界点，用于判断inside
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ctx.moveTo(xStart, yStart);
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for (let i = 0, end = n * 2 - 1, ri; i < end; i++) {
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ri = i % 2 === 0 ? r0 : r;
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ctx.lineTo(x + ri * cos(deg), y + ri * sin(deg));
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deg += dStep;
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}
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ctx.closePath();
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}
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}
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Star.prototype.type = 'star';
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export default Star;
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