[GIS] OpenLayers3: How to draw line with beetwen two points

javascriptopenlayers

I've following code:

var source = new ol.source.Vector();
var vector = new ol.layer.Vector({
  source: source
  style: new ol.style.Style({
    stroke: new ol.style.Stroke({
      color: "#ffcc33",
      width: 2
    })
  })
});

map.addLayer(vector);

var drawInteraction = new ol.interaction.Draw({
  source: source,
  type: "LineString"
});

map.addInteraction(drawInteraction);

How I can draw only 2 points start and end?

Best Answer

This is only available in OpenLayers master version, not a release as yet, but there is a new config option on ol.interaction.Draw called maxPoints see: http://openlayers.org/en/master/apidoc/ol.interaction.Draw.html

The relevant pull request which brought in this new functionality is: https://github.com/openlayers/ol3/pull/3673

Related Solutions

[GIS] How to clear a vector layer before drawstart in openlayers 3

Points are a bit tricky because the drawstart and drawend events are driven from the same mouse click. To support all geometry types, have a look at the sample code below.

If you only ever need to support the ol.geom.Point type, then just use the drawend event and don't worry about the rest.

Sample Code

var geomType, lastFeature;

var source = new ol.source.Vector({
    wrapX: false
});

var draw = new ol.interaction.Draw({
    source: source,
    type: geomType
});

// removes the last feature from the vector source.
var removeLastFeature = function() {
    if (lastFeature)
      source.removeFeature(lastFeature);
};

// On draw start for polygon, line and circle types we need to 
// remove the previous feature so that it doesn't show.
draw.on('drawstart', function (e) {

    // Filter on all BUT points
    if (geomType !== 'Point')) {
       source.clear();  // implicit remove of last feature.
    }

});

// When a drawing ends for a point feature, remove the last feature
draw.on('drawend', function (e) {

    // Filter on points ONLY
    if (geomType === 'Point') {
        removeLastFeature();
    }
    lastFeature = e.feature;

});

map.addInteraction(draw);

jsFiddle

See a complete example here that handles all geometry types: https://jsfiddle.net/abb54n79/1/

[GIS] How to get the geometry type of a WFS vector layer in OpenLayers 3

The geometry type is information you need to retrieve from the WFS server. OpenLayers cannot know. The way to do this is a DescribeFeatureType request. The response is an XML Schema, which will contain the data types for geometry and attributes. For the geometry, you will find something like

<xsd:element maxOccurs="1" minOccurs="0" name="the_geom" nillable="true" type="gml:MultiSurfacePropertyType"/>

In your application, you will need to map from the available GML geometry types to one of the WFS relevant geometry types that OpenLayers knows (Point, LineString, Polygon, MultiPoint, MultiLineString, MultiPolygon). In the above snippet, it would be MultiPolygon.

Instead of parsing the XSD manually, you can also try JSONIX and its OGC Schemas extension to get the DescribeFeatureType response as JavaScript object.

Best Answer

Related Solutions

[GIS] How to clear a vector layer before drawstart in openlayers 3

[GIS] How to get the geometry type of a WFS vector layer in OpenLayers 3

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