/* 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/Control/ZoomBox.js
 * @requires OpenLayers/Control/DragPan.js
 * @requires OpenLayers/Handler/MouseWheel.js
 * 
 * Class: OpenLayers.Control.Navigation
 * The navigation control handles map browsing with mouse events (dragging,
 *     double-clicking, and scrolling the wheel).  Create a new navigation 
 *     control with the <OpenLayers.Control.Navigation> control.  
 * 
 *     Note that this control is added to the map by default (if no controls 
 *     array is sent in the options object to the <OpenLayers.Map> 
 *     constructor).
 * 
 * Inherits:
 *  - <OpenLayers.Control>
 */
OpenLayers.Control.Navigation = OpenLayers.Class(OpenLayers.Control, {

    /** 
     * Property: dragPan
     * {<OpenLayers.Control.DragPan>} 
     */
    dragPan: null,

    /** 
     * Property: zoomBox
     * {<OpenLayers.Control.ZoomBox>}
     */
    zoomBox: null,

    /** 
     * Property: wheelHandler
     * {<OpenLayers.Handler.MouseWheel>}
     */
    wheelHandler: null,

    /**
     * Constructor: OpenLayers.Control.Navigation
     * Create a new navigation control
     * 
     * Parameters:
     * options - {Object} An optional object whose properties will be set on
     *                    the control
     */
    initialize: function(options) {
        OpenLayers.Control.prototype.initialize.apply(this, arguments);
    },

    /**
     * Method: activate
     */
    activate: function() {
        this.dragPan.activate();
        this.wheelHandler.activate();
        this.zoomBox.activate();
        return OpenLayers.Control.prototype.activate.apply(this,arguments);
    },

    /**
     * Method: deactivate
     */
    deactivate: function() {
        this.zoomBox.deactivate();
        this.dragPan.deactivate();
        this.wheelHandler.deactivate();
        return OpenLayers.Control.prototype.deactivate.apply(this,arguments);
    },
    
    /**
     * Method: draw
     */
    draw: function() {
        this.map.events.register( "dblclick", this, this.defaultDblClick );
        this.dragPan = new OpenLayers.Control.DragPan({map: this.map});
        this.zoomBox = new OpenLayers.Control.ZoomBox(
                    {map: this.map, keyMask: OpenLayers.Handler.MOD_SHIFT});
        this.dragPan.draw();
        this.zoomBox.draw();
        this.wheelHandler = new OpenLayers.Handler.MouseWheel(
                                    this, {"up"  : this.wheelUp,
                                           "down": this.wheelDown} );
        this.activate();
    },

    /**
     * Method: defaultDblClick 
     * 
     * Parameters:
     * evt - {Event} 
     */
    defaultDblClick: function (evt) {
        var newCenter = this.map.getLonLatFromViewPortPx( evt.xy ); 
        this.map.setCenter(newCenter, this.map.zoom + 1);
        OpenLayers.Event.stop(evt);
        return false;
    },

    /**
     * Method: wheelChange  
     *
     * Parameters:
     * evt - {Event}
     */
    wheelChange: function(evt, deltaZ) {
        var newZoom = this.map.getZoom() + deltaZ;
        if (!this.map.isValidZoomLevel(newZoom)) return;

        var size    = this.map.getSize();
        var deltaX  = size.w/2 - evt.xy.x;
        var deltaY  = evt.xy.y - size.h/2;
        var newRes  = this.map.baseLayer.resolutions[newZoom];
        var zoomPoint = this.map.getLonLatFromPixel(evt.xy);
        var newCenter = new OpenLayers.LonLat(
                            zoomPoint.lon + deltaX * newRes,
                            zoomPoint.lat + deltaY * newRes );
        this.map.setCenter( newCenter, newZoom );
    },

    /** 
     * Method: wheelUp
     * User spun scroll wheel up
     * 
     * Parameters:
     * evt - {Event}
     */
    wheelUp: function(evt) {
        this.wheelChange(evt, 1);
    },

    /** 
     * Method: wheelDown
     * User spun scroll wheel down
     * 
     * Parameters:
     * evt - {Event}
     */
    wheelDown: function(evt) {
        this.wheelChange(evt, -1);
    },

    CLASS_NAME: "OpenLayers.Control.Navigation"
});