Current File : /home/tradevaly/www/node_modules/zrender/src/graphic/shape/Ellipse.js

/**
 * 椭圆形状
 * @module zrender/graphic/shape/Ellipse
 */

import Path from '../Path';

export default Path.extend({

    type: 'ellipse',

    shape: {
        cx: 0, cy: 0,
        rx: 0, ry: 0
    },

    buildPath: function (ctx, shape) {
        var k = 0.5522848;
        var x = shape.cx;
        var y = shape.cy;
        var a = shape.rx;
        var b = shape.ry;
        var ox = a * k; // 水平控制点偏移量
        var oy = b * k; // 垂直控制点偏移量
        // 从椭圆的左端点开始顺时针绘制四条三次贝塞尔曲线
        ctx.moveTo(x - a, y);
        ctx.bezierCurveTo(x - a, y - oy, x - ox, y - b, x, y - b);
        ctx.bezierCurveTo(x + ox, y - b, x + a, y - oy, x + a, y);
        ctx.bezierCurveTo(x + a, y + oy, x + ox, y + b, x, y + b);
        ctx.bezierCurveTo(x - ox, y + b, x - a, y + oy, x - a, y);
        ctx.closePath();
    }
});