zh/builder/src/zrender3/contain/arc.js

import { normalizeRadian } from './util';
var PI2 = Math.PI * 2;
/**
 * 圆弧描边包含判断
 * @param  {number}  cx
 * @param  {number}  cy
 * @param  {number}  r
 * @param  {number}  startAngle
 * @param  {number}  endAngle
 * @param  {boolean}  anticlockwise
 * @param  {number} lineWidth
 * @param  {number}  x
 * @param  {number}  y
 * @return {Boolean}
 */

export function containStroke(cx, cy, r, startAngle, endAngle, anticlockwise, lineWidth, x, y) {
  if (lineWidth === 0) {
    return false;
  }

  var _l = lineWidth;
  x -= cx;
  y -= cy;
  var d = Math.sqrt(x * x + y * y);

  if (d - _l > r || d + _l < r) {
    return false;
  }

  if (Math.abs(startAngle - endAngle) % PI2 < 1e-4) {
    // Is a circle
    return true;
  }

  if (anticlockwise) {
    var tmp = startAngle;
    startAngle = normalizeRadian(endAngle);
    endAngle = normalizeRadian(tmp);
  } else {
    startAngle = normalizeRadian(startAngle);
    endAngle = normalizeRadian(endAngle);
  }

  if (startAngle > endAngle) {
    endAngle += PI2;
  }

  var angle = Math.atan2(y, x);

  if (angle < 0) {
    angle += PI2;
  }

  return angle >= startAngle && angle <= endAngle || angle + PI2 >= startAngle && angle + PI2 <= endAngle;
}