OpenLayers 矢量層最大特征數

Question

我想知道是否可以限制您在 vectorylayer 上繪制的功能數量。 如果我已經繪制了一個多邊形，然后再繪制另一個多邊形，它將刪除第一個要素。

如果不是，是否可以向矢量圖層添加一個偵聽器，以便在單擊繪制時可以擦除所有功能？

謝謝！！！

Answer 1

您不能在 Vector Layer 上設置最大功能數，但它有很多事件，您可以在其中注入自己的邏輯。 以下是可用事件：

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

例如，您可以使用“beforefeatureAdded”：

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

Answer 2

你可以制作一個按鈕，當你點擊它時，它會刪除矢量圖層中的所有特征：

map.layers[1].removeAllFeatures();

這里 1 是我的層的 id（我的矢量圖層是 OSM 層之后的第二層）

祝你好運 ！