1. //如何是绘制正方方和矩形需要特殊处理
    2. /* 
    3. @param{string}source 待添加的数据源
    4. @param{string} type 不同的类型(Point,LineString,Polygon,Circle,Square,Box)
    5. @param{function} callback 绘制完成调用
    6.  */
    7. //draw.js
    8. function createDraw({source, type="Point", callback}) {
    9.     let draw = null
    10.     let geometryFunction = null
    11.     let maxPoints = 0
    12.     if (type == 'Square') {
    13.       type = 'Circle'
    14.       geometryFunction = ol.interaction.Draw.createRegularPolygon(4)
    15.     } else if (type == 'Rectangle') {
    16.       type = 'LineString'
    17.       geometryFunction = function (coordinates, geometry) {
    18.         if (!geometry) {
    19.           //多边形
    20.           geometry = new ol.geom.Polygon(null)
    21.         }
    22.         var start = coordinates[0]
    23.         var end = coordinates[1]
    24.         geometry.setCoordinates([
    25.             [start,[start[0],end[1]],end,[end[0],start[1]],start]
    26.         ])
    27.         return geometry
    28.       }
    29.       maxPoints = 2
    30.     }
    32.     draw = new ol.interaction.Draw({
    33.       source: source,
    34.       type: type,
    35.       geometryFunction: geometryFunction,
    36.       maxPoints: maxPoints,
    37.     })
    39.     // callback && draw.on('drawend', callback)
    41.     if (callback) {
    42.       draw.on('drawend', callback)
    43.     }
    45.     return draw
    46.   }