OpenLayers Vector Layer最大特征数

Question

我想知道是否有可能限制你在矢量层上绘制的特征数量。如果我已经画了一个多边形，然后再画一个，它会删除第一个特征。

如果没有，是否可以添加一个监听器到矢量层，这样我就可以擦除所有的特征时，点击绘制?

谢谢! !

Answer 1

你不能在Vector Layer上设置最大数量的特征，但它有很多事件，你可以在其中注入自己的逻辑。以下是可用的事件:

"beforefeatureadded", "beforefeaturesadded",
"featureadded", "featuresadded", "beforefeatureremoved",
"beforefeaturesremoved", "featureremoved", "featuresremoved",
"beforefeatureselected", "featureselected", "featureunselected", 
"beforefeaturemodified", "featuremodified", "afterfeaturemodified",
"vertexmodified", "vertexremoved", "sketchstarted",
"sketchmodified", "sketchcomplete", "refresh"

你可以使用"beforefeatureadded"，例如:

your_vectror_layer.events.on({'beforefeatureadded': function(){
  //Remove first feature or whatever you want to do
}});

Answer 2

你可以创建一个按钮，当你点击它时，它会删除矢量图层中的所有特征:

map.layers [1] .removeAllFeatures ();

这里1是我的图层的id(我的矢量图层是OSM图层之后的第二个图层)

祝你好运