在重新绘制OpenLayers之前清除WMS图层 [英] Clear WMS layer before redraw on OpenLayers

问题描述

我目前正在使用OpenLayers（Vector和WMS）成功显示多个图层。
我的应用程序允许用户修改一些参数，这些参数将：

*修改绑定

*修改地图中心

*修改WMS图像

我使用Ajax来避免页面重新加载，它工作得很好，但是当某些图层需要一段时间加载时，尚未重新绘制的其他图层仍会在后台显示（但根本不相关）到我的新语境）。
我想在重新询问服务器以获取新图像之前清除WMS图层（如果可能），但还没有找到任何内容。
我通过调用removeAllFeature（）来在向量层上执行此操作;

感谢您的帮助！

<当用户点击按钮时，这是我的伪代码：

  $。getJSON（url / updateMapConfig.php ，
 {
 data：$（this）.serialize（），
 ajax：'true'，
 cache：'false'
}，
 function（j）{
 if（j.result =='ok'）{
 var layersToShow = []; 
 //刷新矢量图层
（var i = 0 ; i< map.layers.length; i ++）{
 if（map.layers [i] .isVector）{
 map.layers [i] .removeAllFeatures（）; 
 map.layers [i] .refresh（{force：true}）; //向量图层
} 
} 
 //为（var i = 0; i< map）刷新可见图层
 .layers.length; i ++）{
 if（map.layers [i] .visibility&&！map.layers [i] .isBaseLayer&&！map.layers [i] .isVecto r）{//刷新可见的非基础
 map.layers [i] .redraw（true）; //其他图层
} 
} 
 //设置新边界
 var bounds = new OpenLayers.Bounds（）; 
 bounds.extend（new OpenLayers.LonLat（j.bounds.xmin-100，j.bounds.ymin-100））; 
 bounds.extend（new OpenLayers.LonLat（parseInt（j.bounds.xmax）+100，parseInt（j.bounds.ymax）+100））; 
 map.zoomToExtent（bounds）; 
 //移动到目的地点
 if（j.poiCenter！=）{
 eval（map.setCenter（new OpenLayers.LonLat（+ j.poiCenter +）） ）; 
} 
} 
} 
）; 
  

解决方案

我终于找到了使用clearGrid的快乐结局（ ）在重绘它们之前对每一层进行操作。

我还发现如果有任何正在运行，此函数将停止平铺加载。
示例我有两个基础层：EmptyLayer和WhateverTiledBGLayer。
如果花费20秒加载WhateverTiledBGLayer图块，即使用户选择切换到空图层，我也可以看到服务器对WhateverTiledBGLayer上剩余图块的请求。

简单地调用WhateverTiledBGLayer.clearGrid（）将停止请求图层。

感谢您的帮助。

I'm currently successfully displaying multiple layers using OpenLayers (Vector and WMS). My application allow the user to modify some parameters, which will :
* modify bound
* modify map center
* modify the WMS image
I use Ajax to avoid page reload, it works nicely, however when some layers take a while to load, the others which are not yet redrawn are still shown in the background (but aren't related at all to my new context). I would like to clear WMS layers (if possible) before re-asking the server for the new image but didn't find anything yet. I do this on the vector layer by calling removeAllFeature();

Thanks for any help !

Here is my pseudo-code when the user click the button :

$.getJSON("url/updateMapConfig.php",
    {  
      data: $(this).serialize() ,   
      ajax: 'true',   
      cache: 'false'  
    },   
    function(j){  
      if (j.result == 'ok') {  
        var layersToShow = [];  
        // Refresh vector layer  
        for(var i=0;i<map.layers.length;i++) {  
          if (map.layers[i].isVector) {  
            map.layers[i].removeAllFeatures();  
            map.layers[i].refresh({force:true}); // Vector layer  
          }   
        }  
        // Refresh visible layers  
        for(var i=0;i<map.layers.length;i++) {  
          if (map.layers[i].visibility && !map.layers[i].isBaseLayer && !map.layers[i].isVector) { // Refresh visible non base  
              map.layers[i].redraw(true); // Other layer  
          }  
        }  
        // Set new bounds  
        var bounds = new OpenLayers.Bounds();  
          bounds.extend(new OpenLayers.LonLat(j.bounds.xmin-100, j.bounds.ymin-100));  
          bounds.extend(new OpenLayers.LonLat(parseInt(j.bounds.xmax)+100, parseInt(j.bounds.ymax)+100));  
        map.zoomToExtent(bounds);  
        // Move to destination point  
        if (j.poiCenter != "") {  
          eval("map.setCenter(new OpenLayers.LonLat("+j.poiCenter+"))");  
        }  
      }  
    }  
);  

解决方案

I finally found out an happy ending using the clearGrid() function on every layer before redrawing them.

I also found that this function will stop tile loading if any is running. Example I had two base layer : EmptyLayer and WhateverTiledBGLayer. if it tooks 20s to load WhateverTiledBGLayer tiles, even if the user chose to switch to empty layer, I could see the request done to the server for the remaining tiles on WhateverTiledBGLayer.

Simply calling WhateverTiledBGLayer.clearGrid() will stop requesting layers.

Thanks for help.

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