105 lines
2.5 KiB
JavaScript
105 lines
2.5 KiB
JavaScript
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var _vector = require("../../core/vector");
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var v2Min = _vector.min;
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var v2Max = _vector.max;
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var v2Scale = _vector.scale;
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var v2Distance = _vector.distance;
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var v2Add = _vector.add;
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var v2Clone = _vector.clone;
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var v2Sub = _vector.sub;
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/**
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* 贝塞尔平滑曲线
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* @module zrender/shape/util/smoothBezier
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* @author pissang (https://www.github.com/pissang)
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* Kener (@Kener-林峰, kener.linfeng@gmail.com)
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* errorrik (errorrik@gmail.com)
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*/
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/**
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* 贝塞尔平滑曲线
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* @alias module:zrender/shape/util/smoothBezier
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* @param {Array} points 线段顶点数组
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* @param {number} smooth 平滑等级, 0-1
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* @param {boolean} isLoop
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* @param {Array} constraint 将计算出来的控制点约束在一个包围盒内
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* 比如 [[0, 0], [100, 100]], 这个包围盒会与
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* 整个折线的包围盒做一个并集用来约束控制点。
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* @param {Array} 计算出来的控制点数组
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*/
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function _default(points, smooth, isLoop, constraint) {
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var cps = [];
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var v = [];
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var v1 = [];
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var v2 = [];
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var prevPoint;
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var nextPoint;
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var min;
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var max;
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if (constraint) {
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min = [Infinity, Infinity];
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max = [-Infinity, -Infinity];
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for (var i = 0, len = points.length; i < len; i++) {
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v2Min(min, min, points[i]);
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v2Max(max, max, points[i]);
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} // 与指定的包围盒做并集
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v2Min(min, min, constraint[0]);
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v2Max(max, max, constraint[1]);
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}
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for (var i = 0, len = points.length; i < len; i++) {
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var point = points[i];
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if (isLoop) {
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prevPoint = points[i ? i - 1 : len - 1];
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nextPoint = points[(i + 1) % len];
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} else {
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if (i === 0 || i === len - 1) {
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cps.push(v2Clone(points[i]));
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continue;
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} else {
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prevPoint = points[i - 1];
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nextPoint = points[i + 1];
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}
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}
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v2Sub(v, nextPoint, prevPoint); // use degree to scale the handle length
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v2Scale(v, v, smooth);
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var d0 = v2Distance(point, prevPoint);
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var d1 = v2Distance(point, nextPoint);
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var sum = d0 + d1;
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if (sum !== 0) {
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d0 /= sum;
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d1 /= sum;
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}
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v2Scale(v1, v, -d0);
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v2Scale(v2, v, d1);
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var cp0 = v2Add([], point, v1);
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var cp1 = v2Add([], point, v2);
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if (constraint) {
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v2Max(cp0, cp0, min);
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v2Min(cp0, cp0, max);
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v2Max(cp1, cp1, min);
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v2Min(cp1, cp1, max);
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}
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cps.push(cp0);
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cps.push(cp1);
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}
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if (isLoop) {
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cps.push(cps.shift());
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}
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return cps;
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}
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module.exports = _default;
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