openlayers/lib/OpenLayers/Handler/Point.js

/* Copyright (c) 2006-2007 MetaCarta, Inc., published under the BSD license.
 * See http://svn.openlayers.org/trunk/openlayers/release-license.txt 
 * for the full text of the license. */


/**
 * @requires OpenLayers/Handler.js
 * @requires OpenLayers/Geometry/Point.js
 * 
 * Class: OpenLayers.Handler.Point
 * Handler to draw a point on the map.  Point is displayed on mouse down,
 * moves on mouse move, and is finished on mouse up.  The handler triggers
 * callbacks for 'done' and 'cancel'.  Create a new instance with the
 * <OpenLayers.Handler.Point> constructor.
 * 
 * Inherits from:
 *  - <OpenLayers.Handler>
 */
OpenLayers.Handler.Point = OpenLayers.Class(OpenLayers.Handler, {
    
    /**
     * Property: point
     * {<OpenLayers.Feature.Vector>} The currently drawn point
     */
    point: null,

    /**
     * Property: layer
     * {<OpenLayers.Layer.Vector>} The temporary drawing layer
     */
    layer: null,
    
    /**
     * Property: drawing 
     * {Boolean} A point is being drawn
     */
    drawing: false,
    
    /**
     * Property: mouseDown
     * {Boolean} The mouse is down
     */
    mouseDown: false,

    /**
     * Property: lastDown
     * {<OpenLayers.Pixel>} Location of the last mouse down
     */
    lastDown: null,

    /**
     * Property: lastUp
     * {<OpenLayers.Pixel>}
     */
    lastUp: null,

    /**
     * Constructor: OpenLayers.Handler.Point
     * Create a new point handler.
     *
     * Parameters:
     * control - {<OpenLayers.Control>} The control that owns this handler
     * callbacks - {Object} An object with a 'done' property whos value is a
     *             function to be called when the point drawing is finished.
     *             The callback should expect to recieve a single argument,
     *             the point geometry.  If the callbacks object contains a
     *             'cancel' property, this function will be called when the
     *             handler is deactivated while drawing.  The cancel should
     *             expect to receive a geometry.
     * options - {Object} An optional object with properties to be set on the
     *           handler
     */
    initialize: function(control, callbacks, options) {
        // TBD: deal with style
        this.style = OpenLayers.Util.extend(OpenLayers.Feature.Vector.style['default'], {});

        OpenLayers.Handler.prototype.initialize.apply(this, arguments);
    },
    
    /**
     * APIMethod: activate
     * turn on the handler
     */
    activate: function() {
        if(!OpenLayers.Handler.prototype.activate.apply(this, arguments)) {
            return false;
        }
        // create temporary vector layer for rendering geometry sketch
        // TBD: this could be moved to initialize/destroy - setting visibility here
        var options = {displayInLayerSwitcher: false};
        this.layer = new OpenLayers.Layer.Vector(this.CLASS_NAME, options);
        this.map.addLayer(this.layer);
        return true;
    },
    
    /**
     * Method: createFeature
     * Add temporary features
     */
    createFeature: function() {
        this.point = new OpenLayers.Feature.Vector(
                                              new OpenLayers.Geometry.Point());
    },

    /**
     * APIMethod: deactivate
     * turn off the handler
     */
    deactivate: function() {
        if(!OpenLayers.Handler.prototype.deactivate.apply(this, arguments)) {
            return false;
        }
        // call the cancel callback if mid-drawing
        if(this.drawing) {
            this.cancel();
        }
        this.map.removeLayer(this.layer, false);
        this.layer.destroy();
        this.layer = null;
        return true;
    },
    
    /**
     * Method: destroyFeature
     * Destroy the temporary geometries
     */
    destroyFeature: function() {
        this.point.destroy();
        this.point = null;
    },

    /**
     * Method: finalize
     * Finish the geometry and call the "done" callback.
     */
    finalize: function() {
        this.layer.renderer.clear();
        this.callback("done", [this.geometryClone()]);
        this.destroyFeature();
        this.drawing = false;
        this.mouseDown = false;
        this.lastDown = null;
        this.lastUp = null;
    },

    /**
     * APIMethod: cancel
     * Finish the geometry and call the "cancel" callback.
     */
    cancel: function() {
        this.layer.renderer.clear();
        this.callback("cancel", [this.geometryClone()]);
        this.destroyFeature();
        this.drawing = false;
        this.mouseDown = false;
        this.lastDown = null;
        this.lastUp = null;
    },

    /**
     * Method: dblclick
     * Handle double clicks.
     * 
     * Parameters:
     * evt - {Event} The browser event
     *
     * Returns: 
     * {Boolean} Allow event propagation
     */
    dblclick: function(evt) {
        OpenLayers.Event.stop(evt);
        return false;
    },
    
    /**
     * Method: drawFeature
     * Render features on the temporary layer.
     */
    drawFeature: function() {
        this.layer.drawFeature(this.point, this.style);
    },
    
    /**
     * Method: geometryClone
     * Return a clone of the relevant geometry.
     *
     * Returns:
     * {<OpenLayers.Geometry.Point>}
     */
    geometryClone: function() {
        return this.point.geometry.clone();
    },
  
    /**
     * Method: mousedown
     * Handle mouse down.  Adjust the geometry and redraw.
     * Return determines whether to propagate the event on the map.
     * 
     * Parameters:
     * evt - {Event} The browser event
     *
     * Returns: 
     * {Boolean} Allow event propagation
     */
    mousedown: function(evt) {
        // check keyboard modifiers
        if(!this.checkModifiers(evt)) {
            return true;
        }
        // ignore double-clicks
        if(this.lastDown && this.lastDown.equals(evt.xy)) {
            return true;
        }
        if(this.lastDown == null) {
            this.createFeature();
        }
        this.lastDown = evt.xy;
        this.drawing = true;
        var lonlat = this.map.getLonLatFromPixel(evt.xy);
        this.point.geometry.x = lonlat.lon;
        this.point.geometry.y = lonlat.lat;
        this.drawFeature();
        return false;
    },

    /**
     * Method: mousemove
     * Handle mouse move.  Adjust the geometry and redraw.
     * Return determines whether to propagate the event on the map.
     * 
     * Parameters:
     * evt - {Event} The browser event
     *
     * Returns: 
     * {Boolean} Allow event propagation
     */
    mousemove: function (evt) {
        if(this.drawing) {
            var lonlat = this.map.getLonLatFromPixel(evt.xy);
            this.point.geometry.x = lonlat.lon;
            this.point.geometry.y = lonlat.lat;
            this.point.geometry.clearBounds();
            this.drawFeature();
        }
        return true;
    },

    /**
     * Method: mouseup
     * Handle mouse up.  Send the latest point in the geometry to the control.
     * Return determines whether to propagate the event on the map.
     *
     * Parameters:
     * evt - {Event} The browser event
     *
     * Returns: 
     * {Boolean} Allow event propagation
     */
    mouseup: function (evt) {
        if(this.drawing) {
            this.finalize();
            return false;
        } else {
            return true;
        }
    },

    CLASS_NAME: "OpenLayers.Handler.Point"
});