[英]Zooming an OpenLayers3 map to cover multiple vector layers
I have an OpenLayers3 map consisting of an OSM Tile layer and one or more Vector layers. 我有一个OpenLayers3地图,包含一个OSM Tile图层和一个或多个Vector图层。 I can zoom the map into a single layer using
我可以使用将地图缩放为单个图层
vector.addEventListener("change", function() {
map.getView().fitExtent(vectorSource.getExtent(), map.getSize());
});
and this works. 这很有效。 However, if I try to zoom to cover multiple layers using the following in the loop that adds layers
但是,如果我尝试在添加图层的循环中使用以下内容缩放以覆盖多个图层
vector.addEventListener("change", function () {
if (bounds == null) {
bounds = vectorSource.getExtent();
} else {
bounds = bounds.extend(vectorSource.getExtent());
}
map.getView().fitExtent(bounds, map.getSize());
});
with bounds being declared outside the loop, then maps with a single layer continue to work. 如果在循环外声明了边界,那么具有单个图层的地图将继续工作。 However, with more than one layer, the code in the else block give the error "undefined is not a function".
但是,如果有多个图层,则else块中的代码会给出错误“undefined is not a function”。
According to the documentation getExtent() returns an extent object and the extent object has an extend method , so I'm not sure why this errors. 根据文档getExtent()返回一个extent对象 , 而extent对象有一个extend方法 ,所以我不确定为什么会出现这个错误。
Answering own question as I worked it out. 在我解决问题时回答了自己的问题。 I was using extend wrongly.
我错误地使用了扩展。 The correct code is:
正确的代码是:
vector.addEventListener("change", function () {
if (bounds == null) {
bounds = vectorSource.getExtent();
} else {
bounds = ol.extent.extend(bounds, vectorSource.getExtent());
}
map.getView().fitExtent(bounds, map.getSize());
});
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