forked from zhurui/management
57 lines
1.2 KiB
JavaScript
57 lines
1.2 KiB
JavaScript
var Path = require("../Path");
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/**
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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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var PI = Math.PI;
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var cos = Math.cos;
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var sin = Math.sin;
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var _default = Path.extend({
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type: 'star',
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shape: {
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cx: 0,
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cy: 0,
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n: 3,
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r0: null,
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r: 0
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},
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buildPath: function (ctx, shape) {
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var n = shape.n;
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if (!n || n < 2) {
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return;
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}
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var x = shape.cx;
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var y = shape.cy;
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var r = shape.r;
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var r0 = shape.r0; // 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 // 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) // 二三四角星的特殊处理
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: r / 3;
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}
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var dStep = PI / n;
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var deg = -PI / 2;
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var xStart = x + r * cos(deg);
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var yStart = y + r * sin(deg);
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deg += dStep; // 记录边界点，用于判断inside
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ctx.moveTo(xStart, yStart);
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for (var 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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module.exports = _default; |