Richard Duivenvoorde wrote: > Hi, > > I'm using the DrawFeature control to let users define linestrings. I can > capture the doubleclick event (for ending the line) using > lineLayer.onFeatureInsert > > But I cannot find a way to check something WHILE clicking/adding the > segments. Actually on the addition of every segment I want to be able to > count the number of segments, because I want to be sure the will be not > more then 20 segments in certain lines. > OpenLayers.Handler.Path has two callback "done" and "point". The latter is called for every point added to the path while the user is drawing on the map. Here is the "draw-feature.html" example from openlayers distribution slightly modified to show you how attach your custom defined callback handler (see the comment into javascript code) Regards, Saverio Rutigliano
<html xmlns="http://www.w3.org/1999/xhtml";> <head> <style type="text/css"> #map { width: 512px; height: 350px; border: 1px solid gray; } #controlToggle li { list-style: none; } p { width: 512px; } </style> <script src="../lib/OpenLayers.js"></script> <script type="text/javascript"> <!-- var map, drawControls; OpenLayers.Util.onImageLoadErrorColor = "transparent"; function init(){ map = new OpenLayers.Map('map'); var wmsLayer = new OpenLayers.Layer.WMS( "OpenLayers WMS", "http://labs.metacarta.com/wms/vmap0?";, {layers: 'basic'}); var pointLayer = new OpenLayers.Layer.Vector("Point Layer"); var lineLayer = new OpenLayers.Layer.Vector("Line Layer"); var polygonLayer = new OpenLayers.Layer.Vector("Polygon Layer"); map.addLayers([wmsLayer, pointLayer, lineLayer, polygonLayer]); map.addControl(new OpenLayers.Control.LayerSwitcher()); map.addControl(new OpenLayers.Control.MousePosition()); var options = {handlerOptions: {freehand: true}}; // HERE YOU SPECIFY THE ADDITIONAL callbacks PROPERTY WITH CALLBACK HANDLER AVAILABLE FOR THE OpenLayers.Handler.Path (i.e. done and point) var pathDrawFeatureOptions = { callbacks : {"done": doneHandler, "point": pointHandler}, handlerOptions: {freehand: true}}; drawControls = { point: new OpenLayers.Control.DrawFeature(pointLayer, OpenLayers.Handler.Point), line: new OpenLayers.Control.DrawFeature(lineLayer, OpenLayers.Handler.Path, pathDrawFeatureOptions), // specify the custom "pathDrawFeatureOptions" polygon: new OpenLayers.Control.DrawFeature(polygonLayer, OpenLayers.Handler.Polygon, options) }; for(var key in drawControls) { map.addControl(drawControls[key]); } map.setCenter(new OpenLayers.LonLat(0, 0), 3); document.getElementById('noneToggle').checked = true; } // HERE YOU SPECIFY THE CALLBACK HANDLERS: doneHandler() CALLED WHEN USER FINISHES THE PATH AND pointHandler() CALLED FOR EVERY POINT ADDED // BTW: console.log IS THE FIREBUG METHOD TO WRITE DIRECTILY TO THE CONSOLE... JUST FOR DEBUG function doneHandler(lineGeom) { console.log("doneHandler:" + lineGeom.getComponentsString()); } var gPointCount = 0; function pointHandler(aPoint) { gPointCount++; console.log("pointHandler:point n." + gPointCount + " geom = " + aPoint.toShortString()); } function toggleControl(element) { for(key in drawControls) { var control = drawControls[key]; if(element.value == key && element.checked) { control.activate(); } else { control.deactivate(); } } } // --> </script> </head> <body onload="init()"> <h1>OpenLayers Draw Feature Example</h1> <div id="map"></div> <ul id="controlToggle"> <li> <input type="radio" name="type" value="none" id="noneToggle" onclick="toggleControl(this);" checked="checked" /> <label for="noneToggle">navigate</label> </li> <li> <input type="radio" name="type" value="point" id="pointToggle" onclick="toggleControl(this);" /> <label for="pointToggle">draw point</label> </li> <li> <input type="radio" name="type" value="line" id="lineToggle" onclick="toggleControl(this);" /> <label for="lineToggle">draw line</label> </li> <li> <input type="radio" name="type" value="polygon" id="polygonToggle" onclick="toggleControl(this);" /> <label for="polygonToggle">draw polygon</label> </li> </ul> <p>Feature digitizing is in freehand mode by default. In freehand mode, the mouse is treated as a pen. Drawing begins on mouse down, continues with every mouse move, and ends with mouse up.</p> <p>To turn freehand mode off, hold down the shift key while digitizing. With freehand mode off, one vertex is added with each click and double-clicks finish drawing. Freehand mode can be toggled on and off at any time while drawing.</p> </body> </html> _______________________________________________ Users mailing list [email protected] http://openlayers.org/mailman/listinfo/users
