/**
 * @requires OpenLayers/Control.js
 */

/**
 * Class: OpenLayers.Control.Swipe
 * The Swipe control will reveal/hide a target layer right/left side of mouse mouse position on the map.
 * 
 * Inherits from: - <OpenLayers.Control>
 */
OpenLayers.Control.Swipe = OpenLayers.Class(OpenLayers.Control, {
    
    /**
     * Property: layer
     * {<OpenLayers.Layer>} The target layer to be swiped
     */
    layer : null,
    
    /**
     * Property: layerContainerDiv
     * {DOMElement} Layer container div used to read panning offset
     */
    layerContainerDiv : null,
    
    /**
     * Property: div
     * {DOMElement} Layer div for CSS clip manipulation
     */
    div : null,

    /**
     * Constructor: OpenLayers.Control.Swipe
     * 
     * Parameters:
     * layer - {OpenLayers.Layer} Target layer for the swipe effect.
     * options - {Object} An optional object whose properties will be used to extend the control.
     */
    initialize : function(layer, options) {
        // setup properties to be used for swipe logic
        this.map = layer.map;
        this.layer = layer;
        this.div = this.layer.div;
        this.layerContainerDiv = this.layer.map.layerContainerDiv;

        OpenLayers.Control.prototype.initialize.apply(this, [ options ]);
    },

    /**
     * APIMethod: activate
     * Activate the control.
     */
    activate : function() {
        var activated = OpenLayers.Control.prototype.activate.call(this);
        
        if (activated) {
            this.map.events.on({
                mousemove : this.onMousemove,
                scope : this
            });
        }
    },

    /**
     * APIMethod: deactivate
     * Deactivate the control.
     */
    deactivate : function() {
        var deactivated = OpenLayers.Control.prototype.deactivate.call(this);

        if (deactivated) {
            this.div.style.clip = '';

            this.map.events.un({
                mousemove : this.onMousemove,
                scope : this
            });
        }
    },

    /**
     * Method: onMousemove
     * Registered as a listener for mousemove events on the map. Calculates clip region
     * that will create the swipe effect.
     *
     * Parameters:
     * e - {Object} The mousemove event.
     */
    onMousemove : function(e) {
        var offsetX = (e.clientX - this.map.div.offsetLeft) - this.layerContainerDiv.offsetLeft;
        var offsetY = -this.layerContainerDiv.offsetTop;

        var top = offsetY;
        var right = this.map.getSize().w + offsetX;
        var bottom = this.map.getSize().h + offsetY;
        var left = offsetX;

        this.div.style.clip = 'rect(' + top + 'px ' + right + 'px ' + bottom + 'px ' + left + 'px)';
    },

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