META-INF.assets.rjzjh.zrender.graphic.shape.Star.js Maven / Gradle / Ivy
/**
* n角星（n>3）
* @module zrender/graphic/shape/Star
*/
define(function (require) {
var PI = Math.PI;
var cos = Math.cos;
var sin = Math.sin;
return require('../Path').extend({
type: 'star',
shape: {
cx: 0,
cy: 0,
n: 3,
r0: null,
r: 0
},
buildPath: function (ctx, shape) {
var n = shape.n;
if (!n || n < 2) {
return;
}
var x = shape.cx;
var y = shape.cy;
var r = shape.r;
var 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;
}
var dStep = PI / n;
var deg = -PI / 2;
var xStart = x + r * cos(deg);
var yStart = y + r * sin(deg);
deg += dStep;
// 记录边界点，用于判断inside
ctx.moveTo(xStart, yStart);
for (var 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();
}
});
});