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