[GIS] How to select WFS features by polygon in OpenLayers

openlayers-2polygon

I need to be able to select features on a wfs layer using a polygon instead of a box. I was hoping this would be a standard option in the SelectFeature class. Too bad this isn't the case.

Any implementation suggestions?

Best Answer

You can use the layer.filter property on the vector layer then refresh the layer.

layer.filter = new OpenLayers.Filter.Spatial({
    type: OpenLayers.Filter.Spatial.INTERSECTS,
    value: event.feature.geometry
});
layer.refresh({force: true});

Here's the Example

Granted this will make all the non-selected layers disappear, but you can possibly do this just to collect the array of features (without refreshing the layer) then use the SelectFeature class to select only the ones the filter returned.

Related Solutions

[GIS] How to fire a function after all features have been selected by a box in OpenLayers

You could modify selectBox method of SelectFeature control:

OpenLayers.Control.SelectFeature.prototype.selectBox = function(position) {
if (position instanceof OpenLayers.Bounds) {
    var minXY = this.map.getLonLatFromPixel(
        new OpenLayers.Pixel(position.left, position.bottom)
    );
    var maxXY = this.map.getLonLatFromPixel(
        new OpenLayers.Pixel(position.right, position.top)
    );
    var bounds = new OpenLayers.Bounds(
        minXY.lon, minXY.lat, maxXY.lon, maxXY.lat
    );

    // if multiple is false, first deselect currently selected features
    if (!this.multipleSelect()) {
        this.unselectAll();
    }

    // because we're using a box, we consider we want multiple selection
    var prevMultiple = this.multiple;
    this.multiple = true;
    var layers = this.layers || [this.layer];
    var layer;
    var selectedFeatures = []; // <-- Modification of original function (1/3)
    for(var l=0; l<layers.length; ++l) {
        layer = layers[l];
        for(var i=0, len = layer.features.length; i<len; ++i) {
            var feature = layer.features[i];
            // check if the feature is displayed
            if (!feature.getVisibility()) {
                continue;
            }

            if (this.geometryTypes == null || OpenLayers.Util.indexOf(
                this.geometryTypes, feature.geometry.CLASS_NAME) > -1) {
                    if (bounds.toGeometry().intersects(feature.geometry)) {
                        if (OpenLayers.Util.indexOf(layer.selectedFeatures, feature) == -1) {
                            this.select(feature);
                            selectedFeatures.push(feature); // <-- Modification of original function (2/3)
                        }
                    }
                }
            }
    }
    onFeatureSelect(selectedFeatures); // <-- Modification of original function (3/3)
    this.multiple = prevMultiple;
    }
}

Live example

[GIS] OpenLayers ZoomBox control kills SelectFeature event firing

You could add button for SelectFeature control into panel and deactivate ZoomBox control when SelectFeature control is active. Here is my little example.

Best Answer

Related Solutions

[GIS] How to fire a function after all features have been selected by a box in OpenLayers

[GIS] OpenLayers ZoomBox control kills SelectFeature event firing

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