OpenLayers 3 实现划线，画点

 //划线
     this.drawLine = function (type) {
         //清除双击放大效果
         this.map.getInteractions().item(1).setActive(false);
         var draw = new ol.interaction.Draw({
             source: _vector.getSource(),
             type: (type == 'point' ? 'Point' : 'LineString'),
             style: new ol.style.Style({
                 fill: new ol.style.Fill({
                     color: 'rgba(255, 255, 255, 0.2)'
                 }),
                 //划线的时候的图样
                 stroke: new ol.style.Stroke({
                     color: 'rgba(0, 0, 0, 0.5)',
                     lineDash: [10, 10],
                     width: 2
                 }),
                 image: new ol.style.Circle({
                     radius: 5,
                     stroke: new ol.style.Stroke({
                         color: 'rgba(0, 0, 0, 0.7)'
                     }),
                     fill: new ol.style.Fill({
                         color: 'rgba(255, 255, 255, 0.2)'
                     })
                 })
             })
         });
         this.map.addInteraction(draw);
         //画好线的操作
         draw.on('drawend', function (evt) {
             this.map.removeInteraction(draw);
         },this)

     }