[GIS] Drawing pie charts with vectors with OpenLayers

mapsopenlayersvector

Has any one got any examples of drawing pie charts with vectors as markers with OpenLayers?

Best Answer

An example can be found at this website:

http://thematicmapping.org/playground/openlayers_piecharts_geojson_google_chart.php

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[GIS] How to remove last drawing feature in OpenLayers 3

You can use something like this -

var features = vectorSource.getFeatures();
var lastFeature = features[features.length - 1];
vectorSource.removeFeature(lastFeature);

Note that you need to vectorSource.getFeatures() every time you want to remove the last feature or use it in a function.

[GIS] How to get all the Layer Vectors added to a Map in OpenLayers 3

The newer versions of OpenLayers allow you to get all map layers regardless of class name etc. with the map.getLayers() function. This function returns an ol.Collection object.

Take a look at the answer here, it's an older solution to the same problem as yours: https://stackoverflow.com/questions/30121024/openlayers-3-zoom-to-combined-extent

It's a little outdated now (map.getView().fitExtent has been renamed to .fit for example) so I've adapted the code for your scenario.

Given that you appear to be using groups, it's also necessary to include a check for whether or not the current layer is actually a group; and if it is, to loop through all sub-layers.

//Create an empty extent that we will gradually extend
var extent = ol.extent.createEmpty();

map.getLayers().forEach(function(layer) {
    //If this is actually a group, we need to create an inner loop to go through its individual layers
    if(layer instanceof ol.layer.Group) {
        layer.getLayers().forEach(function(groupLayer) {
            //If this is a vector layer, add it to our extent
            if(layer instanceof ol.layer.Vector)
                ol.extent.extend(extent, groupLayer.getSource().getExtent());
        });
    }
    else if(layer instanceof ol.layer.Vector)
       ol.extent.extend(extent, layer.getSource().getExtent());
});

//Finally fit the map's view to our combined extent
map.getView().fit(extent, map.getSize());

Best Answer

Related Solutions

[GIS] How to remove last drawing feature in OpenLayers 3

[GIS] How to get all the Layer Vectors added to a Map in OpenLayers 3

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