[GIS] OpenLayers SelectFeature – Manually set feature as selected/unselected

openlayers-2

In the OpenLayers SelectFeature, how can I manually set a feature as selected/unselected and have it reflect the appropriate color?

For instance, when my application loads, it sends back the existing select state which I want to set on the polygons. Thanks!

Best Answer

I noticed that there are two methods which can be used to select a feature manually.

Method select(feature) in the SelectFeatures control.
Method clickFeature(feature) in the SelectFeatures control.

Here's a fiddle demonstrating that feature in case anyone else is interested.

At one point, I wasn't able to get select to work. Setting selectFeature.allowSelection to true let me select it, but later I noticed that it worked without it so I'm not sure when setting that to true is required. If you run into any issues, you might want to try playing with that attribute. Looking into the source further should allow us to understand the purpose of that variable.

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Switch last 2 statements. Add to map first, then activate.

[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

Best Answer

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