zh/builder/src/zrender3/graphic/helper/poly.js

import smoothSpline from './smoothSpline';
import smoothBezier from './smoothBezier';
export function buildPath(ctx, shape, closePath) {
  var points = shape.points;
  var smooth = shape.smooth;

  if (points && points.length >= 2) {
    if (smooth && smooth !== 'spline') {
      var controlPoints = smoothBezier(points, smooth, closePath, shape.smoothConstraint);
      ctx.moveTo(points[0][0], points[0][1]);
      var len = points.length;

      for (var i = 0; i < (closePath ? len : len - 1); i++) {
        var cp1 = controlPoints[i * 2];
        var cp2 = controlPoints[i * 2 + 1];
        var p = points[(i + 1) % len];
        ctx.bezierCurveTo(cp1[0], cp1[1], cp2[0], cp2[1], p[0], p[1]);
      }
    } else {
      if (smooth === 'spline') {
        points = smoothSpline(points, closePath);
      }

      ctx.moveTo(points[0][0], points[0][1]);

      for (var i = 1, l = points.length; i < l; i++) {
        ctx.lineTo(points[i][0], points[i][1]);
      }
    }

    closePath && ctx.closePath();
  }
}