leaflet地图全图以及框选截图导出功能(附源码下载)

前言

leaflet 入门开发系列环境知识点了解：

leaflet api文档介绍，详细介绍 leaflet 每个类的函数以及属性等等

leaflet 在线例子

leaflet 插件，leaflet 的插件库，非常有用

内容概览

leaflet地图截图导出功能
源代码demo下载

效果图如下：

本篇主要参考截图插件domtoimage:https://github.com/tsayen/dom-to-image
地图全图导出直接用上面的domtoimage插件，然后矩形框选截图导出也是在domtoimage插件基础上自己计算矩形范围来实现的

部分代码，完整的见源码demo下载

<script> 
 var geojsonLayer = null; 
 var map = L.map('map'); 
  L.tileLayer('http://map.geoq.cn/ArcGIS/rest/services/ChinaOnlineStreetPurplishBlue/MapServer/tile/{z}/{y}/{x}',{crossOrigin:true}).addTo(map); 
 
  map.setView(L.latLng(22.95186415, 113.90271877), 14);  //设置缩放级别及中心点 
 
  map.pm.addControls({ 
 position: 'topleft', 
 drawCircle: false, 
 drawMarker:false, 
 drawCircleMarker:false, 
 drawPolyline:false, 
 drawRectangle:false, 
 drawPolygon:false, 
 cutPolygon:false, 
 removalMode:false, 
 editMode:false, 
 dragMode:false 
  }); 
 //参考截图插件:https://github.com/tsayen/dom-to-image 
 var node = document.getElementById('map'); 
  $("#mapexport_btn").click(function(){ 
      domtoimage.toJpeg(node, { quality: 1.0 }) 
        .then(function (dataUrl) { 
 var link = document.createElement('a'); 
            link.download = '全图导出.jpeg'; 
            link.href = dataUrl; 
            link.click(); 
        }); 
  }); 
  $("#rctanglexport_btn").click(function(){ 
 //绘制矩形 
      map.pm.enableDraw("Rectangle", { 
 finishOn: "dblclick", 
 allowSelfIntersection: false, 
 tooltips: false 
      }); 
  }); 
  map.on('pm:create', e => { 
 //console.log(e); 
    geojsonLayer = e.layer; 
    geojsonLayer.addTo(map); 
 
 var northEast =  e.layer.getBounds()._northEast; 
 var southWest =  e.layer.getBounds()._southWest; 
 //框选矩形的中心点 
 var centerPoint = L.latLng( 
          (northEast.lat + southWest.lat) / 2.0, 
          (northEast.lng + southWest.lng) / 2.0 
    ); 
 //地理坐标转换屏幕坐标 
 var northEastPoint = map.latLngToContainerPoint(northEast); 
 var southWestPoint = map.latLngToContainerPoint(southWest); 
 ……
 ……
 
 if(geojsonLayer){ 
         map.removeLayer(geojsonLayer); 
         geojsonLayer = null; 
    } 
    domtoimage 
          .toPng(node) 
          .then(function(dataUrl) { 
 if (dataUrl.length <= 6) { 
 console.log("屏幕截图结果为空,建议放大地图,重新截图操作试试看"); 
 return; 
            } 
 //过渡img图片,为了截取img指定位置的截图需要 
 var img = new Image(); 
            img.src = dataUrl; 
            img.onload = function() { 
               ……
               ……
            }; 
          }) 
          .catch(function(error) { 
 console.error("oops, something went wrong!", error); 
          }); 
  }); 
</script>