bd028579
 易尊强
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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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