| /** |
| * n角星(n>3) |
| * @module zrender/graphic/shape/Star |
| */ |
| import Path from '../Path'; |
| var PI = Math.PI; |
| var cos = Math.cos; |
| var sin = Math.sin; |
| export default 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(); |
| } |
| }); |