dragdrop.js

/**
 * The drag and drop utility provides a framework for building drag and drop
 * applications.  In addition to enabling drag and drop for specific elements,
 * the drag and drop elements are tracked by the manager class, and the
 * interactions between the various elements are tracked during the drag and
 * the implementing code is notified about these important moments.
 * @module dragdrop
 * @title Drag and Drop
 * @requires yahoo,dom,event
 * @namespace YAHOO.util
 */

// Only load the library once.  Rewriting the manager class would orphan 
// existing drag and drop instances.
if (!YAHOO.util.DragDropMgr) {

/**
 * DragDropMgr is a singleton that tracks the element interaction for 
 * all DragDrop items in the window.  Generally, you will not call 
 * this class directly, but it does have helper methods that could 
 * be useful in your DragDrop implementations.
 * @class DragDropMgr
 * @static
 */
YAHOO.util.DragDropMgr = function() {

    var Event = YAHOO.util.Event,
        Dom = YAHOO.util.Dom;

    return {
        /**
        * This property is used to turn on global use of the shim element on all DragDrop instances, defaults to false for backcompat. (Use: YAHOO.util.DDM.useShim = true)
        * @property useShim
        * @type Boolean
        * @static
        */
        useShim: false,
        /**
        * This property is used to determine if the shim is active over the screen, default false.
        * @private
        * @property _shimActive
        * @type Boolean
        * @static
        */
        _shimActive: false,
        /**
        * This property is used when useShim is set on a DragDrop object to store the current state of DDM.useShim so it can be reset when a drag operation is done.
        * @private
        * @property _shimState
        * @type Boolean
        * @static
        */
        _shimState: false,
        /**
        * This property is used when useShim is set to true, it will set the opacity on the shim to .5 for debugging. Use: (YAHOO.util.DDM._debugShim = true;)
        * @private
        * @property _debugShim
        * @type Boolean
        * @static
        */
        _debugShim: false,
        /**
        * This method will create a shim element (giving it the id of yui-ddm-shim), it also attaches the mousemove and mouseup listeners to it and attaches a scroll listener on the window
        * @private
        * @method _sizeShim
        * @static
        */
        _createShim: function() {
            var s = document.createElement('div');
            s.id = 'yui-ddm-shim';
            if (document.body.firstChild) {
                document.body.insertBefore(s, document.body.firstChild);
            } else {
                document.body.appendChild(s);
            }
            s.style.display = 'none';
            s.style.backgroundColor = 'red';
            s.style.position = 'absolute';
            s.style.zIndex = '99999';
            Dom.setStyle(s, 'opacity', '0');
            this._shim = s;
            Event.on(s, "mouseup",   this.handleMouseUp, this, true);
            Event.on(s, "mousemove", this.handleMouseMove, this, true);
            Event.on(window, 'scroll', this._sizeShim, this, true);
        },
        /**
        * This method will size the shim, called from activate and on window scroll event
        * @private
        * @method _sizeShim
        * @static
        */
        _sizeShim: function() {
            if (this._shimActive) {
                var s = this._shim;
                s.style.height = Dom.getDocumentHeight() + 'px';
                s.style.width = Dom.getDocumentWidth() + 'px';
                s.style.top = '0';
                s.style.left = '0';
            }
        },
        /**
        * This method will create the shim element if needed, then show the shim element, size the element and set the _shimActive property to true
        * @private
        * @method _activateShim
        * @static
        */
        _activateShim: function() {
            if (this.useShim) {
                if (!this._shim) {
                    this._createShim();
                }
                this._shimActive = true;
                var s = this._shim,
                    o = '0';
                if (this._debugShim) {
                    o = '.5';
                }
                Dom.setStyle(s, 'opacity', o);
                this._sizeShim();
                s.style.display = 'block';
            }
        },
        /**
        * This method will hide the shim element and set the _shimActive property to false
        * @private
        * @method _deactivateShim
        * @static
        */
        _deactivateShim: function() {
            this._shim.style.display = 'none';
            this._shimActive = false;
        },
        /**
        * The HTML element created to use as a shim over the document to track mouse movements
        * @private
        * @property _shim
        * @type HTMLElement
        * @static
        */
        _shim: null,
        /**
         * Two dimensional Array of registered DragDrop objects.  The first 
         * dimension is the DragDrop item group, the second the DragDrop 
         * object.
         * @property ids
         * @type {string: string}
         * @private
         * @static
         */
        ids: {},

        /**
         * Array of element ids defined as drag handles.  Used to determine 
         * if the element that generated the mousedown event is actually the 
         * handle and not the html element itself.
         * @property handleIds
         * @type {string: string}
         * @private
         * @static
         */
        handleIds: {},

        /**
         * the DragDrop object that is currently being dragged
         * @property dragCurrent
         * @type DragDrop
         * @private
         * @static
         **/
        dragCurrent: null,

        /**
         * the DragDrop object(s) that are being hovered over
         * @property dragOvers
         * @type Array
         * @private
         * @static
         */
        dragOvers: {},

        /**
         * the X distance between the cursor and the object being dragged
         * @property deltaX
         * @type int
         * @private
         * @static
         */
        deltaX: 0,

        /**
         * the Y distance between the cursor and the object being dragged
         * @property deltaY
         * @type int
         * @private
         * @static
         */
        deltaY: 0,

        /**
         * Flag to determine if we should prevent the default behavior of the
         * events we define. By default this is true, but this can be set to 
         * false if you need the default behavior (not recommended)
         * @property preventDefault
         * @type boolean
         * @static
         */
        preventDefault: true,

        /**
         * Flag to determine if we should stop the propagation of the events 
         * we generate. This is true by default but you may want to set it to
         * false if the html element contains other features that require the
         * mouse click.
         * @property stopPropagation
         * @type boolean
         * @static
         */
        stopPropagation: true,

        /**
         * Internal flag that is set to true when drag and drop has been
         * initialized
         * @property initialized
         * @private
         * @static
         */
        initialized: false,

        /**
         * All drag and drop can be disabled.
         * @property locked
         * @private
         * @static
         */
        locked: false,

        /**
         * Provides additional information about the the current set of
         * interactions.  Can be accessed from the event handlers. It
         * contains the following properties:
         *
         *       out:       onDragOut interactions
         *       enter:     onDragEnter interactions
         *       over:      onDragOver interactions
         *       drop:      onDragDrop interactions
         *       point:     The location of the cursor
         *       draggedRegion: The location of dragged element at the time
         *                      of the interaction
         *       sourceRegion: The location of the source elemtn at the time
         *                     of the interaction
         *       validDrop: boolean
         * @property interactionInfo
         * @type object
         * @static
         */
        interactionInfo: null,

        /**
         * Called the first time an element is registered.
         * @method init
         * @private
         * @static
         */
        init: function() {
            this.initialized = true;
        },

        /**
         * In point mode, drag and drop interaction is defined by the 
         * location of the cursor during the drag/drop
         * @property POINT
         * @type int
         * @static
         * @final
         */
        POINT: 0,

        /**
         * In intersect mode, drag and drop interaction is defined by the 
         * cursor position or the amount of overlap of two or more drag and 
         * drop objects.
         * @property INTERSECT
         * @type int
         * @static
         * @final
         */
        INTERSECT: 1,

        /**
         * In intersect mode, drag and drop interaction is defined only by the 
         * overlap of two or more drag and drop objects.
         * @property STRICT_INTERSECT
         * @type int
         * @static
         * @final
         */
        STRICT_INTERSECT: 2,

        /**
         * The current drag and drop mode.  Default: POINT
         * @property mode
         * @type int
         * @static
         */
        mode: 0,

        /**
         * Runs method on all drag and drop objects
         * @method _execOnAll
         * @private
         * @static
         */
        _execOnAll: function(sMethod, args) {
            for (var i in this.ids) {
                for (var j in this.ids[i]) {
                    var oDD = this.ids[i][j];
                    if (! this.isTypeOfDD(oDD)) {
                        continue;
                    }
                    oDD[sMethod].apply(oDD, args);
                }
            }
        },

        /**
         * Drag and drop initialization.  Sets up the global event handlers
         * @method _onLoad
         * @private
         * @static
         */
        _onLoad: function() {

            this.init();

            Event.on(document, "mouseup",   this.handleMouseUp, this, true);
            Event.on(document, "mousemove", this.handleMouseMove, this, true);
            Event.on(window,   "unload",    this._onUnload, this, true);
            Event.on(window,   "resize",    this._onResize, this, true);
            // Event.on(window,   "mouseout",    this._test);

        },

        /**
         * Reset constraints on all drag and drop objs
         * @method _onResize
         * @private
         * @static
         */
        _onResize: function(e) {
            this._execOnAll("resetConstraints", []);
        },

        /**
         * Lock all drag and drop functionality
         * @method lock
         * @static
         */
        lock: function() { this.locked = true; },

        /**
         * Unlock all drag and drop functionality
         * @method unlock
         * @static
         */
        unlock: function() { this.locked = false; },

        /**
         * Is drag and drop locked?
         * @method isLocked
         * @return {boolean} True if drag and drop is locked, false otherwise.
         * @static
         */
        isLocked: function() { return this.locked; },

        /**
         * Location cache that is set for all drag drop objects when a drag is
         * initiated, cleared when the drag is finished.
         * @property locationCache
         * @private
         * @static
         */
        locationCache: {},

        /**
         * Set useCache to false if you want to force object the lookup of each
         * drag and drop linked element constantly during a drag.
         * @property useCache
         * @type boolean
         * @static
         */
        useCache: true,

        /**
         * The number of pixels that the mouse needs to move after the 
         * mousedown before the drag is initiated.  Default=3;
         * @property clickPixelThresh
         * @type int
         * @static
         */
        clickPixelThresh: 3,

        /**
         * The number of milliseconds after the mousedown event to initiate the
         * drag if we don't get a mouseup event. Default=1000
         * @property clickTimeThresh
         * @type int
         * @static
         */
        clickTimeThresh: 1000,

        /**
         * Flag that indicates that either the drag pixel threshold or the 
         * mousdown time threshold has been met
         * @property dragThreshMet
         * @type boolean
         * @private
         * @static
         */
        dragThreshMet: false,

        /**
         * Timeout used for the click time threshold
         * @property clickTimeout
         * @type Object
         * @private
         * @static
         */
        clickTimeout: null,

        /**
         * The X position of the mousedown event stored for later use when a 
         * drag threshold is met.
         * @property startX
         * @type int
         * @private
         * @static
         */
        startX: 0,

        /**
         * The Y position of the mousedown event stored for later use when a 
         * drag threshold is met.
         * @property startY
         * @type int
         * @private
         * @static
         */
        startY: 0,

        /**
         * Flag to determine if the drag event was fired from the click timeout and
         * not the mouse move threshold.
         * @property fromTimeout
         * @type boolean
         * @private
         * @static
         */
        fromTimeout: false,

        /**
         * Each DragDrop instance must be registered with the DragDropMgr.  
         * This is executed in DragDrop.init()
         * @method regDragDrop
         * @param {DragDrop} oDD the DragDrop object to register
         * @param {String} sGroup the name of the group this element belongs to
         * @static
         */
        regDragDrop: function(oDD, sGroup) {
            if (!this.initialized) { this.init(); }
            
            if (!this.ids[sGroup]) {
                this.ids[sGroup] = {};
            }
            this.ids[sGroup][oDD.id] = oDD;
        },

        /**
         * Removes the supplied dd instance from the supplied group. Executed
         * by DragDrop.removeFromGroup, so don't call this function directly.
         * @method removeDDFromGroup
         * @private
         * @static
         */
        removeDDFromGroup: function(oDD, sGroup) {
            if (!this.ids[sGroup]) {
                this.ids[sGroup] = {};
            }

            var obj = this.ids[sGroup];
            if (obj && obj[oDD.id]) {
                delete obj[oDD.id];
            }
        },

        /**
         * Unregisters a drag and drop item.  This is executed in 
         * DragDrop.unreg, use that method instead of calling this directly.
         * @method _remove
         * @private
         * @static
         */
        _remove: function(oDD) {
            for (var g in oDD.groups) {
                if (g) {
                    var item = this.ids[g];
                    if (item && item[oDD.id]) {
                        delete item[oDD.id];
                    }
                }
                
            }
            delete this.handleIds[oDD.id];
        },

        /**
         * Each DragDrop handle element must be registered.  This is done
         * automatically when executing DragDrop.setHandleElId()
         * @method regHandle
         * @param {String} sDDId the DragDrop id this element is a handle for
         * @param {String} sHandleId the id of the element that is the drag 
         * handle
         * @static
         */
        regHandle: function(sDDId, sHandleId) {
            if (!this.handleIds[sDDId]) {
                this.handleIds[sDDId] = {};
            }
            this.handleIds[sDDId][sHandleId] = sHandleId;
        },

        /**
         * Utility function to determine if a given element has been 
         * registered as a drag drop item.
         * @method isDragDrop
         * @param {String} id the element id to check
         * @return {boolean} true if this element is a DragDrop item, 
         * false otherwise
         * @static
         */
        isDragDrop: function(id) {
            return ( this.getDDById(id) ) ? true : false;
        },

        /**
         * Returns the drag and drop instances that are in all groups the
         * passed in instance belongs to.
         * @method getRelated
         * @param {DragDrop} p_oDD the obj to get related data for
         * @param {boolean} bTargetsOnly if true, only return targetable objs
         * @return {DragDrop[]} the related instances
         * @static
         */
        getRelated: function(p_oDD, bTargetsOnly) {
            var oDDs = [];
            for (var i in p_oDD.groups) {
                for (var j in this.ids[i]) {
                    var dd = this.ids[i][j];
                    if (! this.isTypeOfDD(dd)) {
                        continue;
                    }
                    if (!bTargetsOnly || dd.isTarget) {
                        oDDs[oDDs.length] = dd;
                    }
                }
            }

            return oDDs;
        },

        /**
         * Returns true if the specified dd target is a legal target for 
         * the specifice drag obj
         * @method isLegalTarget
         * @param {DragDrop} the drag obj
         * @param {DragDrop} the target
         * @return {boolean} true if the target is a legal target for the 
         * dd obj
         * @static
         */
        isLegalTarget: function (oDD, oTargetDD) {
            var targets = this.getRelated(oDD, true);
            for (var i=0, len=targets.length;i<len;++i) {
                if (targets[i].id == oTargetDD.id) {
                    return true;
                }
            }

            return false;
        },

        /**
         * My goal is to be able to transparently determine if an object is
         * typeof DragDrop, and the exact subclass of DragDrop.  typeof 
         * returns "object", oDD.constructor.toString() always returns
         * "DragDrop" and not the name of the subclass.  So for now it just
         * evaluates a well-known variable in DragDrop.
         * @method isTypeOfDD
         * @param {Object} the object to evaluate
         * @return {boolean} true if typeof oDD = DragDrop
         * @static
         */
        isTypeOfDD: function (oDD) {
            return (oDD && oDD.__ygDragDrop);
        },

        /**
         * Utility function to determine if a given element has been 
         * registered as a drag drop handle for the given Drag Drop object.
         * @method isHandle
         * @param {String} id the element id to check
         * @return {boolean} true if this element is a DragDrop handle, false 
         * otherwise
         * @static
         */
        isHandle: function(sDDId, sHandleId) {
            return ( this.handleIds[sDDId] && 
                            this.handleIds[sDDId][sHandleId] );
        },

        /**
         * Returns the DragDrop instance for a given id
         * @method getDDById
         * @param {String} id the id of the DragDrop object
         * @return {DragDrop} the drag drop object, null if it is not found
         * @static
         */
        getDDById: function(id) {
            for (var i in this.ids) {
                if (this.ids[i][id]) {
                    return this.ids[i][id];
                }
            }
            return null;
        },

        /**
         * Fired after a registered DragDrop object gets the mousedown event.
         * Sets up the events required to track the object being dragged
         * @method handleMouseDown
         * @param {Event} e the event
         * @param oDD the DragDrop object being dragged
         * @private
         * @static
         */
        handleMouseDown: function(e, oDD) {
            //this._activateShim();

            this.currentTarget = YAHOO.util.Event.getTarget(e);

            this.dragCurrent = oDD;

            var el = oDD.getEl();

            // track start position
            this.startX = YAHOO.util.Event.getPageX(e);
            this.startY = YAHOO.util.Event.getPageY(e);

            this.deltaX = this.startX - el.offsetLeft;
            this.deltaY = this.startY - el.offsetTop;

            this.dragThreshMet = false;

            this.clickTimeout = setTimeout( 
                    function() { 
                        var DDM = YAHOO.util.DDM;
                        DDM.startDrag(DDM.startX, DDM.startY);
                        DDM.fromTimeout = true;
                    }, 
                    this.clickTimeThresh );
        },

        /**
         * Fired when either the drag pixel threshold or the mousedown hold 
         * time threshold has been met.
         * @method startDrag
         * @param x {int} the X position of the original mousedown
         * @param y {int} the Y position of the original mousedown
         * @static
         */
        startDrag: function(x, y) {
            if (this.dragCurrent && this.dragCurrent.useShim) {
                this._shimState = this.useShim;
                this.useShim = true;
            }
            this._activateShim();
            clearTimeout(this.clickTimeout);
            var dc = this.dragCurrent;
            if (dc && dc.events.b4StartDrag) {
                dc.b4StartDrag(x, y);
                dc.fireEvent('b4StartDragEvent', { x: x, y: y });
            }
            if (dc && dc.events.startDrag) {
                dc.startDrag(x, y);
                dc.fireEvent('startDragEvent', { x: x, y: y });
            }
            this.dragThreshMet = true;
        },

        /**
         * Internal function to handle the mouseup event.  Will be invoked 
         * from the context of the document.
         * @method handleMouseUp
         * @param {Event} e the event
         * @private
         * @static
         */
        handleMouseUp: function(e) {
            if (this.dragCurrent) {
                clearTimeout(this.clickTimeout);

                if (this.dragThreshMet) {
                    if (this.fromTimeout) {
                        this.fromTimeout = false;
                        this.handleMouseMove(e);
                    }
                    this.fromTimeout = false;
                    this.fireEvents(e, true);
                } else {
                }

                this.stopDrag(e);

                this.stopEvent(e);
            }
        },

        /**
         * Utility to stop event propagation and event default, if these 
         * features are turned on.
         * @method stopEvent
         * @param {Event} e the event as returned by this.getEvent()
         * @static
         */
        stopEvent: function(e) {
            if (this.stopPropagation) {
                YAHOO.util.Event.stopPropagation(e);
            }

            if (this.preventDefault) {
                YAHOO.util.Event.preventDefault(e);
            }
        },

        /** 
         * Ends the current drag, cleans up the state, and fires the endDrag
         * and mouseUp events.  Called internally when a mouseup is detected
         * during the drag.  Can be fired manually during the drag by passing
         * either another event (such as the mousemove event received in onDrag)
         * or a fake event with pageX and pageY defined (so that endDrag and
         * onMouseUp have usable position data.).  Alternatively, pass true
         * for the silent parameter so that the endDrag and onMouseUp events
         * are skipped (so no event data is needed.)
         *
         * @method stopDrag
         * @param {Event} e the mouseup event, another event (or a fake event) 
         *                  with pageX and pageY defined, or nothing if the 
         *                  silent parameter is true
         * @param {boolean} silent skips the enddrag and mouseup events if true
         * @static
         */
        stopDrag: function(e, silent) {
            var dc = this.dragCurrent;
            // Fire the drag end event for the item that was dragged
            if (dc && !silent) {
                if (this.dragThreshMet) {
                    if (dc.events.b4EndDrag) {
                        dc.b4EndDrag(e);
                        dc.fireEvent('b4EndDragEvent', { e: e });
                    }
                    if (dc.events.endDrag) {
                        dc.endDrag(e);
                        dc.fireEvent('endDragEvent', { e: e });
                    }
                }
                if (dc.events.mouseUp) {
                    dc.onMouseUp(e);
                    dc.fireEvent('mouseUpEvent', { e: e });
                }
            }

            if (this._shimActive) {
                this._deactivateShim();
                if (this.dragCurrent && this.dragCurrent.useShim) {
                    this.useShim = this._shimState;
                    this._shimState = false;
                }
            }

            this.dragCurrent = null;
            this.dragOvers = {};
        },

        /** 
         * Internal function to handle the mousemove event.  Will be invoked 
         * from the context of the html element.
         *
         * @TODO figure out what we can do about mouse events lost when the 
         * user drags objects beyond the window boundary.  Currently we can 
         * detect this in internet explorer by verifying that the mouse is 
         * down during the mousemove event.  Firefox doesn't give us the 
         * button state on the mousemove event.
         * @method handleMouseMove
         * @param {Event} e the event
         * @private
         * @static
         */
        handleMouseMove: function(e) {

            var dc = this.dragCurrent;
            if (dc) {

                // var button = e.which || e.button;

                // check for IE < 9 mouseup outside of page boundary
                if ((YAHOO.util.Event.isIE < 9) && !e.button) {
                    this.stopEvent(e);
                    return this.handleMouseUp(e);
                } else {
                    if (e.clientX < 0 || e.clientY < 0) {
                        //This will stop the element from leaving the viewport in FF, Opera & Safari
                        //Not turned on yet
                        //this.stopEvent(e);
                        //return false;
                    }
                }

                if (!this.dragThreshMet) {
                    var diffX = Math.abs(this.startX - YAHOO.util.Event.getPageX(e));
                    var diffY = Math.abs(this.startY - YAHOO.util.Event.getPageY(e));
                    if (diffX > this.clickPixelThresh || 
                                diffY > this.clickPixelThresh) {
                        this.startDrag(this.startX, this.startY);
                    }
                }

                if (this.dragThreshMet) {
                    if (dc && dc.events.b4Drag) {
                        dc.b4Drag(e);
                        dc.fireEvent('b4DragEvent', { e: e});
                    }
                    if (dc && dc.events.drag) {
                        dc.onDrag(e);
                        dc.fireEvent('dragEvent', { e: e});
                    }
                    if (dc) {
                        this.fireEvents(e, false);
                    }
                }

                this.stopEvent(e);
            }
        },
        
        /**
         * Iterates over all of the DragDrop elements to find ones we are 
         * hovering over or dropping on
         * @method fireEvents
         * @param {Event} e the event
         * @param {boolean} isDrop is this a drop op or a mouseover op?
         * @private
         * @static
         */
        fireEvents: function(e, isDrop) {
            var dc = this.dragCurrent;

            // If the user did the mouse up outside of the window, we could 
            // get here even though we have ended the drag.
            // If the config option dragOnly is true, bail out and don't fire the events
            if (!dc || dc.isLocked() || dc.dragOnly) {
                return;
            }

            var x = YAHOO.util.Event.getPageX(e),
                y = YAHOO.util.Event.getPageY(e),
                pt = new YAHOO.util.Point(x,y),
                pos = dc.getTargetCoord(pt.x, pt.y),
                el = dc.getDragEl(),
                events = ['out', 'over', 'drop', 'enter'],
                curRegion = new YAHOO.util.Region( pos.y, 
                                               pos.x + el.offsetWidth,
                                               pos.y + el.offsetHeight, 
                                               pos.x ),
            
                oldOvers = [], // cache the previous dragOver array
                inGroupsObj  = {},
                inGroups  = [],
                data = {
                    outEvts: [],
                    overEvts: [],
                    dropEvts: [],
                    enterEvts: []
                };


            // Check to see if the object(s) we were hovering over is no longer 
            // being hovered over so we can fire the onDragOut event
            for (var i in this.dragOvers) {

                var ddo = this.dragOvers[i];

                if (! this.isTypeOfDD(ddo)) {
                    continue;
                }
                if (! this.isOverTarget(pt, ddo, this.mode, curRegion)) {
                    data.outEvts.push( ddo );
                }

                oldOvers[i] = true;
                delete this.dragOvers[i];
            }

            for (var sGroup in dc.groups) {
                
                if ("string" != typeof sGroup) {
                    continue;
                }

                for (i in this.ids[sGroup]) {
                    var oDD = this.ids[sGroup][i];
                    if (! this.isTypeOfDD(oDD)) {
                        continue;
                    }

                    if (oDD.isTarget && !oDD.isLocked() && oDD != dc) {
                        if (this.isOverTarget(pt, oDD, this.mode, curRegion)) {
                            inGroupsObj[sGroup] = true;
                            // look for drop interactions
                            if (isDrop) {
                                data.dropEvts.push( oDD );
                            // look for drag enter and drag over interactions
                            } else {

                                // initial drag over: dragEnter fires
                                if (!oldOvers[oDD.id]) {
                                    data.enterEvts.push( oDD );
                                // subsequent drag overs: dragOver fires
                                } else {
                                    data.overEvts.push( oDD );
                                }

                                this.dragOvers[oDD.id] = oDD;
                            }
                        }
                    }
                }
            }

            this.interactionInfo = {
                out:       data.outEvts,
                enter:     data.enterEvts,
                over:      data.overEvts,
                drop:      data.dropEvts,
                point:     pt,
                draggedRegion:    curRegion,
                sourceRegion: this.locationCache[dc.id],
                validDrop: isDrop
            };

            
            for (var inG in inGroupsObj) {
                inGroups.push(inG);
            }

            // notify about a drop that did not find a target
            if (isDrop && !data.dropEvts.length) {
                this.interactionInfo.validDrop = false;
                if (dc.events.invalidDrop) {
                    dc.onInvalidDrop(e);
                    dc.fireEvent('invalidDropEvent', { e: e });
                }
            }
            for (i = 0; i < events.length; i++) {
                var tmp = null;
                if (data[events[i] + 'Evts']) {
                    tmp = data[events[i] + 'Evts'];
                }
                if (tmp && tmp.length) {
                    var type = events[i].charAt(0).toUpperCase() + events[i].substr(1),
                        ev = 'onDrag' + type,
                        b4 = 'b4Drag' + type,
                        cev = 'drag' + type + 'Event',
                        check = 'drag' + type;
                    if (this.mode) {
                        if (dc.events[b4]) {
                            dc[b4](e, tmp, inGroups);
                            dc.fireEvent(b4 + 'Event', { event: e, info: tmp, group: inGroups });
                            
                        }
                        if (dc.events[check]) {
                            dc[ev](e, tmp, inGroups);
                            dc.fireEvent(cev, { event: e, info: tmp, group: inGroups });
                        }
                    } else {
                        for (var b = 0, len = tmp.length; b < len; ++b) {
                            if (dc.events[b4]) {
                                dc[b4](e, tmp[b].id, inGroups[0]);
                                dc.fireEvent(b4 + 'Event', { event: e, info: tmp[b].id, group: inGroups[0] });
                            }
                            if (dc.events[check]) {
                                dc[ev](e, tmp[b].id, inGroups[0]);
                                dc.fireEvent(cev, { event: e, info: tmp[b].id, group: inGroups[0] });
                            }
                        }
                    }
                }
            }
        },

        /**
         * Helper function for getting the best match from the list of drag 
         * and drop objects returned by the drag and drop events when we are 
         * in INTERSECT mode.  It returns either the first object that the 
         * cursor is over, or the object that has the greatest overlap with 
         * the dragged element.
         * @method getBestMatch
         * @param  {DragDrop[]} dds The array of drag and drop objects 
         * targeted
         * @return {DragDrop}       The best single match
         * @static
         */
        getBestMatch: function(dds) {
            var winner = null;

            var len = dds.length;

            if (len == 1) {
                winner = dds[0];
            } else {
                // Loop through the targeted items
                for (var i=0; i<len; ++i) {
                    var dd = dds[i];
                    // If the cursor is over the object, it wins.  If the 
                    // cursor is over multiple matches, the first one we come
                    // to wins.
                    if (this.mode == this.INTERSECT && dd.cursorIsOver) {
                        winner = dd;
                        break;
                    // Otherwise the object with the most overlap wins
                    } else {
                        if (!winner || !winner.overlap || (dd.overlap &&
                            winner.overlap.getArea() < dd.overlap.getArea())) {
                            winner = dd;
                        }
                    }
                }
            }

            return winner;
        },

        /**
         * Refreshes the cache of the top-left and bottom-right points of the 
         * drag and drop objects in the specified group(s).  This is in the
         * format that is stored in the drag and drop instance, so typical 
         * usage is:
         * <code>
         * YAHOO.util.DragDropMgr.refreshCache(ddinstance.groups);
         * </code>
         * Alternatively:
         * <code>
         * YAHOO.util.DragDropMgr.refreshCache({group1:true, group2:true});
         * </code>
         * @TODO this really should be an indexed array.  Alternatively this
         * method could accept both.
         * @method refreshCache
         * @param {Object} groups an associative array of groups to refresh
         * @static
         */
        refreshCache: function(groups) {

            // refresh everything if group array is not provided
            var g = groups || this.ids;

            for (var sGroup in g) {
                if ("string" != typeof sGroup) {
                    continue;
                }
                for (var i in this.ids[sGroup]) {
                    var oDD = this.ids[sGroup][i];

                    if (this.isTypeOfDD(oDD)) {
                        var loc = this.getLocation(oDD);
                        if (loc) {
                            this.locationCache[oDD.id] = loc;
                        } else {
                            delete this.locationCache[oDD.id];
                        }
                    }
                }
            }
        },

        /**
         * This checks to make sure an element exists and is in the DOM.  The
         * main purpose is to handle cases where innerHTML is used to remove
         * drag and drop objects from the DOM.  IE provides an 'unspecified
         * error' when trying to access the offsetParent of such an element
         * @method verifyEl
         * @param {HTMLElement} el the element to check
         * @return {boolean} true if the element looks usable
         * @static
         */
        verifyEl: function(el) {
            try {
                if (el) {
                    var parent = el.offsetParent;
                    if (parent) {
                        return true;
                    }
                }
            } catch(e) {
            }

            return false;
        },
        
        /**
         * Returns a Region object containing the drag and drop element's position
         * and size, including the padding configured for it
         * @method getLocation
         * @param {DragDrop} oDD the drag and drop object to get the 
         *                       location for
         * @return {YAHOO.util.Region} a Region object representing the total area
         *                             the element occupies, including any padding
         *                             the instance is configured for.
         * @static
         */
        getLocation: function(oDD) {
            if (! this.isTypeOfDD(oDD)) {
                return null;
            }

            var el = oDD.getEl(), pos, x1, x2, y1, y2, t, r, b, l;

            try {
                pos= YAHOO.util.Dom.getXY(el);
            } catch (e) { }

            if (!pos) {
                return null;
            }

            x1 = pos[0];
            x2 = x1 + el.offsetWidth;
            y1 = pos[1];
            y2 = y1 + el.offsetHeight;

            t = y1 - oDD.padding[0];
            r = x2 + oDD.padding[1];
            b = y2 + oDD.padding[2];
            l = x1 - oDD.padding[3];

            return new YAHOO.util.Region( t, r, b, l );
        },

        /**
         * Checks the cursor location to see if it over the target
         * @method isOverTarget
         * @param {YAHOO.util.Point} pt The point to evaluate
         * @param {DragDrop} oTarget the DragDrop object we are inspecting
         * @param {boolean} intersect true if we are in intersect mode
         * @param {YAHOO.util.Region} pre-cached location of the dragged element
         * @return {boolean} true if the mouse is over the target
         * @private
         * @static
         */
        isOverTarget: function(pt, oTarget, intersect, curRegion) {
            // use cache if available
            var loc = this.locationCache[oTarget.id];
            if (!loc || !this.useCache) {
                loc = this.getLocation(oTarget);
                this.locationCache[oTarget.id] = loc;

            }

            if (!loc) {
                return false;
            }

            oTarget.cursorIsOver = loc.contains( pt );

            // DragDrop is using this as a sanity check for the initial mousedown
            // in this case we are done.  In POINT mode, if the drag obj has no
            // contraints, we are done. Otherwise we need to evaluate the 
            // region the target as occupies to determine if the dragged element
            // overlaps with it.
            
            var dc = this.dragCurrent;
            if (!dc || (!intersect && !dc.constrainX && !dc.constrainY)) {

                //if (oTarget.cursorIsOver) {
                //}
                return oTarget.cursorIsOver;
            }

            oTarget.overlap = null;


            // Get the current location of the drag element, this is the
            // location of the mouse event less the delta that represents
            // where the original mousedown happened on the element.  We
            // need to consider constraints and ticks as well.

            if (!curRegion) {
                var pos = dc.getTargetCoord(pt.x, pt.y);
                var el = dc.getDragEl();
                curRegion = new YAHOO.util.Region( pos.y, 
                                                   pos.x + el.offsetWidth,
                                                   pos.y + el.offsetHeight, 
                                                   pos.x );
            }

            var overlap = curRegion.intersect(loc);

            if (overlap) {
                oTarget.overlap = overlap;
                return (intersect) ? true : oTarget.cursorIsOver;
            } else {
                return false;
            }
        },

        /**
         * unload event handler
         * @method _onUnload
         * @private
         * @static
         */
        _onUnload: function(e, me) {
            this.unregAll();
        },

        /**
         * Cleans up the drag and drop events and objects.
         * @method unregAll
         * @private
         * @static
         */
        unregAll: function() {

            if (this.dragCurrent) {
                this.stopDrag();
                this.dragCurrent = null;
            }

            this._execOnAll("unreg", []);

            //for (var i in this.elementCache) {
                //delete this.elementCache[i];
            //}
            //this.elementCache = {};

            this.ids = {};
        },

        /**
         * A cache of DOM elements
         * @property elementCache
         * @private
         * @static
         * @deprecated elements are not cached now
         */
        elementCache: {},
        
        /**
         * Get the wrapper for the DOM element specified
         * @method getElWrapper
         * @param {String} id the id of the element to get
         * @return {YAHOO.util.DDM.ElementWrapper} the wrapped element
         * @private
         * @deprecated This wrapper isn't that useful
         * @static
         */
        getElWrapper: function(id) {
            var oWrapper = this.elementCache[id];
            if (!oWrapper || !oWrapper.el) {
                oWrapper = this.elementCache[id] = 
                    new this.ElementWrapper(YAHOO.util.Dom.get(id));
            }
            return oWrapper;
        },

        /**
         * Returns the actual DOM element
         * @method getElement
         * @param {String} id the id of the elment to get
         * @return {Object} The element
         * @deprecated use YAHOO.util.Dom.get instead
         * @static
         */
        getElement: function(id) {
            return YAHOO.util.Dom.get(id);
        },
        
        /**
         * Returns the style property for the DOM element (i.e., 
         * document.getElById(id).style)
         * @method getCss
         * @param {String} id the id of the elment to get
         * @return {Object} The style property of the element
         * @deprecated use YAHOO.util.Dom instead
         * @static
         */
        getCss: function(id) {
            var el = YAHOO.util.Dom.get(id);
            return (el) ? el.style : null;
        },

        /**
         * Inner class for cached elements
         * @class DragDropMgr.ElementWrapper
         * @for DragDropMgr
         * @private
         * @deprecated
         */
        ElementWrapper: function(el) {
                /**
                 * The element
                 * @property el
                 */
                this.el = el || null;
                /**
                 * The element id
                 * @property id
                 */
                this.id = this.el && el.id;
                /**
                 * A reference to the style property
                 * @property css
                 */
                this.css = this.el && el.style;
            },

        /**
         * Returns the X position of an html element
         * @method getPosX
         * @param el the element for which to get the position
         * @return {int} the X coordinate
         * @for DragDropMgr
         * @deprecated use YAHOO.util.Dom.getX instead
         * @static
         */
        getPosX: function(el) {
            return YAHOO.util.Dom.getX(el);
        },

        /**
         * Returns the Y position of an html element
         * @method getPosY
         * @param el the element for which to get the position
         * @return {int} the Y coordinate
         * @deprecated use YAHOO.util.Dom.getY instead
         * @static
         */
        getPosY: function(el) {
            return YAHOO.util.Dom.getY(el); 
        },

        /**
         * Swap two nodes.  In IE, we use the native method, for others we 
         * emulate the IE behavior
         * @method swapNode
         * @param n1 the first node to swap
         * @param n2 the other node to swap
         * @static
         */
        swapNode: function(n1, n2) {
            if (n1.swapNode) {
                n1.swapNode(n2);
            } else {
                var p = n2.parentNode;
                var s = n2.nextSibling;

                if (s == n1) {
                    p.insertBefore(n1, n2);
                } else if (n2 == n1.nextSibling) {
                    p.insertBefore(n2, n1);
                } else {
                    n1.parentNode.replaceChild(n2, n1);
                    p.insertBefore(n1, s);
                }
            }
        },

        /**
         * Returns the current scroll position
         * @method getScroll
         * @private
         * @static
         */
        getScroll: function () {
            var t, l, dde=document.documentElement, db=document.body;
            if (dde && (dde.scrollTop || dde.scrollLeft)) {
                t = dde.scrollTop;
                l = dde.scrollLeft;
            } else if (db) {
                t = db.scrollTop;
                l = db.scrollLeft;
            } else {
            }
            return { top: t, left: l };
        },

        /**
         * Returns the specified element style property
         * @method getStyle
         * @param {HTMLElement} el          the element
         * @param {string}      styleProp   the style property
         * @return {string} The value of the style property
         * @deprecated use YAHOO.util.Dom.getStyle
         * @static
         */
        getStyle: function(el, styleProp) {
            return YAHOO.util.Dom.getStyle(el, styleProp);
        },

        /**
         * Gets the scrollTop
         * @method getScrollTop
         * @return {int} the document's scrollTop
         * @static
         */
        getScrollTop: function () { return this.getScroll().top; },

        /**
         * Gets the scrollLeft
         * @method getScrollLeft
         * @return {int} the document's scrollTop
         * @static
         */
        getScrollLeft: function () { return this.getScroll().left; },

        /**
         * Sets the x/y position of an element to the location of the
         * target element.
         * @method moveToEl
         * @param {HTMLElement} moveEl      The element to move
         * @param {HTMLElement} targetEl    The position reference element
         * @static
         */
        moveToEl: function (moveEl, targetEl) {
            var aCoord = YAHOO.util.Dom.getXY(targetEl);
            YAHOO.util.Dom.setXY(moveEl, aCoord);
        },

        /**
         * Gets the client height
         * @method getClientHeight
         * @return {int} client height in px
         * @deprecated use YAHOO.util.Dom.getViewportHeight instead
         * @static
         */
        getClientHeight: function() {
            return YAHOO.util.Dom.getViewportHeight();
        },

        /**
         * Gets the client width
         * @method getClientWidth
         * @return {int} client width in px
         * @deprecated use YAHOO.util.Dom.getViewportWidth instead
         * @static
         */
        getClientWidth: function() {
            return YAHOO.util.Dom.getViewportWidth();
        },

        /**
         * Numeric array sort function
         * @method numericSort
         * @static
         */
        numericSort: function(a, b) { return (a - b); },

        /**
         * Internal counter
         * @property _timeoutCount
         * @private
         * @static
         */
        _timeoutCount: 0,

        /**
         * Trying to make the load order less important.  Without this we get
         * an error if this file is loaded before the Event Utility.
         * @method _addListeners
         * @private
         * @static
         */
        _addListeners: function() {
            var DDM = YAHOO.util.DDM;
            if ( YAHOO.util.Event && document ) {
                DDM._onLoad();
            } else {
                if (DDM._timeoutCount > 2000) {
                } else {
                    setTimeout(DDM._addListeners, 10);
                    if (document && document.body) {
                        DDM._timeoutCount += 1;
                    }
                }
            }
        },

        /**
         * Recursively searches the immediate parent and all child nodes for 
         * the handle element in order to determine wheter or not it was 
         * clicked.
         * @method handleWasClicked
         * @param node the html element to inspect
         * @static
         */
        handleWasClicked: function(node, id) {
            if (this.isHandle(id, node.id)) {
                return true;
            } else {
                // check to see if this is a text node child of the one we want
                var p = node.parentNode;

                while (p) {
                    if (this.isHandle(id, p.id)) {
                        return true;
                    } else {
                        p = p.parentNode;
                    }
                }
            }

            return false;
        }

    };

}();

// shorter alias, save a few bytes
YAHOO.util.DDM = YAHOO.util.DragDropMgr;
YAHOO.util.DDM._addListeners();

}

(function() {

var Event=YAHOO.util.Event; 
var Dom=YAHOO.util.Dom;

/**
 * Defines the interface and base operation of items that that can be 
 * dragged or can be drop targets.  It was designed to be extended, overriding
 * the event handlers for startDrag, onDrag, onDragOver, onDragOut.
 * Up to three html elements can be associated with a DragDrop instance:
 * <ul>
 * <li>linked element: the element that is passed into the constructor.
 * This is the element which defines the boundaries for interaction with 
 * other DragDrop objects.</li>
 * <li>handle element(s): The drag operation only occurs if the element that 
 * was clicked matches a handle element.  By default this is the linked 
 * element, but there are times that you will want only a portion of the 
 * linked element to initiate the drag operation, and the setHandleElId() 
 * method provides a way to define this.</li>
 * <li>drag element: this represents an the element that would be moved along
 * with the cursor during a drag operation.  By default, this is the linked
 * element itself as in {@link YAHOO.util.DD}.  setDragElId() lets you define
 * a separate element that would be moved, as in {@link YAHOO.util.DDProxy}
 * </li>
 * </ul>
 * This class should not be instantiated until the onload event to ensure that
 * the associated elements are available.
 * The following would define a DragDrop obj that would interact with any 
 * other DragDrop obj in the "group1" group:
 * <pre>
 *  dd = new YAHOO.util.DragDrop("div1", "group1");
 * </pre>
 * Since none of the event handlers have been implemented, nothing would 
 * actually happen if you were to run the code above.  Normally you would 
 * override this class or one of the default implementations, but you can 
 * also override the methods you want on an instance of the class...
 * <pre>
 *  dd.onDragDrop = function(e, id) {
 *  &nbsp;&nbsp;alert("dd was dropped on " + id);
 *  }
 * </pre>
 * @namespace YAHOO.util
 * @class DragDrop
 * @constructor
 * @param {String} id of the element that is linked to this instance
 * @param {String} sGroup the group of related DragDrop objects
 * @param {object} config an object containing configurable attributes
 *                Valid properties for DragDrop: 
 *                    padding, isTarget, maintainOffset, primaryButtonOnly,
 */
YAHOO.util.DragDrop = function(id, sGroup, config) {
    if (id) {
        this.init(id, sGroup, config); 
    }
};

YAHOO.util.DragDrop.prototype = {
    /**
     * An Object Literal containing the events that we will be using: mouseDown, b4MouseDown, mouseUp, b4StartDrag, startDrag, b4EndDrag, endDrag, mouseUp, drag, b4Drag, invalidDrop, b4DragOut, dragOut, dragEnter, b4DragOver, dragOver, b4DragDrop, dragDrop
     * By setting any of these to false, then event will not be fired.
     * @property events
     * @type object
     */
    events: null,
    /**
    * @method on
    * @description Shortcut for EventProvider.subscribe, see <a href="YAHOO.util.EventProvider.html#subscribe">YAHOO.util.EventProvider.subscribe</a>
    */
    on: function() {
        this.subscribe.apply(this, arguments);
    },
    /**
     * The id of the element associated with this object.  This is what we 
     * refer to as the "linked element" because the size and position of 
     * this element is used to determine when the drag and drop objects have 
     * interacted.
     * @property id
     * @type String
     */
    id: null,

    /**
     * Configuration attributes passed into the constructor
     * @property config
     * @type object
     */
    config: null,

    /**
     * The id of the element that will be dragged.  By default this is same 
     * as the linked element , but could be changed to another element. Ex: 
     * YAHOO.util.DDProxy
     * @property dragElId
     * @type String
     * @private
     */
    dragElId: null, 

    /**
     * the id of the element that initiates the drag operation.  By default 
     * this is the linked element, but could be changed to be a child of this
     * element.  This lets us do things like only starting the drag when the 
     * header element within the linked html element is clicked.
     * @property handleElId
     * @type String
     * @private
     */
    handleElId: null, 

    /**
     * An associative array of HTML tags that will be ignored if clicked.
     * @property invalidHandleTypes
     * @type {string: string}
     */
    invalidHandleTypes: null, 

    /**
     * An associative array of ids for elements that will be ignored if clicked
     * @property invalidHandleIds
     * @type {string: string}
     */
    invalidHandleIds: null, 

    /**
     * An indexted array of css class names for elements that will be ignored
     * if clicked.
     * @property invalidHandleClasses
     * @type string[]
     */
    invalidHandleClasses: null, 

    /**
     * The linked element's absolute X position at the time the drag was 
     * started
     * @property startPageX
     * @type int
     * @private
     */
    startPageX: 0,

    /**
     * The linked element's absolute X position at the time the drag was 
     * started
     * @property startPageY
     * @type int
     * @private
     */
    startPageY: 0,

    /**
     * The group defines a logical collection of DragDrop objects that are 
     * related.  Instances only get events when interacting with other 
     * DragDrop object in the same group.  This lets us define multiple 
     * groups using a single DragDrop subclass if we want.
     * @property groups
     * @type {string: string}
     */
    groups: null,

    /**
     * Individual drag/drop instances can be locked.  This will prevent 
     * onmousedown start drag.
     * @property locked
     * @type boolean
     * @private
     */
    locked: false,

    /**
     * Lock this instance
     * @method lock
     */
    lock: function() { this.locked = true; },

    /**
     * Unlock this instace
     * @method unlock
     */
    unlock: function() { this.locked = false; },

    /**
     * By default, all instances can be a drop target.  This can be disabled by
     * setting isTarget to false.
     * @property isTarget
     * @type boolean
     */
    isTarget: true,

    /**
     * The padding configured for this drag and drop object for calculating
     * the drop zone intersection with this object.
     * @property padding
     * @type int[]
     */
    padding: null,
    /**
     * If this flag is true, do not fire drop events. The element is a drag only element (for movement not dropping)
     * @property dragOnly
     * @type Boolean
     */
    dragOnly: false,

    /**
     * If this flag is true, a shim will be placed over the screen/viewable area to track mouse events. Should help with dragging elements over iframes and other controls.
     * @property useShim
     * @type Boolean
     */
    useShim: false,

    /**
     * Cached reference to the linked element
     * @property _domRef
     * @private
     */
    _domRef: null,

    /**
     * Internal typeof flag
     * @property __ygDragDrop
     * @private
     */
    __ygDragDrop: true,

    /**
     * Set to true when horizontal contraints are applied
     * @property constrainX
     * @type boolean
     * @private
     */
    constrainX: false,

    /**
     * Set to true when vertical contraints are applied
     * @property constrainY
     * @type boolean
     * @private
     */
    constrainY: false,

    /**
     * The left constraint
     * @property minX
     * @type int
     * @private
     */
    minX: 0,

    /**
     * The right constraint
     * @property maxX
     * @type int
     * @private
     */
    maxX: 0,

    /**
     * The up constraint 
     * @property minY
     * @type int
     * @type int
     * @private
     */
    minY: 0,

    /**
     * The down constraint 
     * @property maxY
     * @type int
     * @private
     */
    maxY: 0,

    /**
     * The difference between the click position and the source element's location
     * @property deltaX
     * @type int
     * @private
     */
    deltaX: 0,

    /**
     * The difference between the click position and the source element's location
     * @property deltaY
     * @type int
     * @private
     */
    deltaY: 0,

    /**
     * Maintain offsets when we resetconstraints.  Set to true when you want
     * the position of the element relative to its parent to stay the same
     * when the page changes
     *
     * @property maintainOffset
     * @type boolean
     */
    maintainOffset: false,

    /**
     * Array of pixel locations the element will snap to if we specified a 
     * horizontal graduation/interval.  This array is generated automatically
     * when you define a tick interval.
     * @property xTicks
     * @type int[]
     */
    xTicks: null,

    /**
     * Array of pixel locations the element will snap to if we specified a 
     * vertical graduation/interval.  This array is generated automatically 
     * when you define a tick interval.
     * @property yTicks
     * @type int[]
     */
    yTicks: null,

    /**
     * By default the drag and drop instance will only respond to the primary
     * button click (left button for a right-handed mouse).  Set to true to
     * allow drag and drop to start with any mouse click that is propogated
     * by the browser
     * @property primaryButtonOnly
     * @type boolean
     */
    primaryButtonOnly: true,

    /**
     * The availabe property is false until the linked dom element is accessible.
     * @property available
     * @type boolean
     */
    available: false,

    /**
     * By default, drags can only be initiated if the mousedown occurs in the
     * region the linked element is.  This is done in part to work around a
     * bug in some browsers that mis-report the mousedown if the previous
     * mouseup happened outside of the window.  This property is set to true
     * if outer handles are defined.
     *
     * @property hasOuterHandles
     * @type boolean
     * @default false
     */
    hasOuterHandles: false,

    /**
     * Property that is assigned to a drag and drop object when testing to
     * see if it is being targeted by another dd object.  This property
     * can be used in intersect mode to help determine the focus of
     * the mouse interaction.  DDM.getBestMatch uses this property first to
     * determine the closest match in INTERSECT mode when multiple targets
     * are part of the same interaction.
     * @property cursorIsOver
     * @type boolean
     */
    cursorIsOver: false,

    /**
     * Property that is assigned to a drag and drop object when testing to
     * see if it is being targeted by another dd object.  This is a region
     * that represents the area the draggable element overlaps this target.
     * DDM.getBestMatch uses this property to compare the size of the overlap
     * to that of other targets in order to determine the closest match in
     * INTERSECT mode when multiple targets are part of the same interaction.
     * @property overlap 
     * @type YAHOO.util.Region
     */
    overlap: null,

    /**
     * Code that executes immediately before the startDrag event
     * @method b4StartDrag
     * @private
     */
    b4StartDrag: function(x, y) { },

    /**
     * Abstract method called after a drag/drop object is clicked
     * and the drag or mousedown time thresholds have beeen met.
     * @method startDrag
     * @param {int} X click location
     * @param {int} Y click location
     */
    startDrag: function(x, y) { /* override this */ },

    /**
     * Code that executes immediately before the onDrag event
     * @method b4Drag
     * @private
     */
    b4Drag: function(e) { },

    /**
     * Abstract method called during the onMouseMove event while dragging an 
     * object.
     * @method onDrag
     * @param {Event} e the mousemove event
     */
    onDrag: function(e) { /* override this */ },

    /**
     * Abstract method called when this element fist begins hovering over 
     * another DragDrop obj
     * @method onDragEnter
     * @param {Event} e the mousemove event
     * @param {String|DragDrop[]} id In POINT mode, the element
     * id this is hovering over.  In INTERSECT mode, an array of one or more 
     * dragdrop items being hovered over.
     */
    onDragEnter: function(e, id) { /* override this */ },

    /**
     * Code that executes immediately before the onDragOver event
     * @method b4DragOver
     * @private
     */
    b4DragOver: function(e) { },

    /**
     * Abstract method called when this element is hovering over another 
     * DragDrop obj
     * @method onDragOver
     * @param {Event} e the mousemove event
     * @param {String|DragDrop[]} id In POINT mode, the element
     * id this is hovering over.  In INTERSECT mode, an array of dd items 
     * being hovered over.
     */
    onDragOver: function(e, id) { /* override this */ },

    /**
     * Code that executes immediately before the onDragOut event
     * @method b4DragOut
     * @private
     */
    b4DragOut: function(e) { },

    /**
     * Abstract method called when we are no longer hovering over an element
     * @method onDragOut
     * @param {Event} e the mousemove event
     * @param {String|DragDrop[]} id In POINT mode, the element
     * id this was hovering over.  In INTERSECT mode, an array of dd items 
     * that the mouse is no longer over.
     */
    onDragOut: function(e, id) { /* override this */ },

    /**
     * Code that executes immediately before the onDragDrop event
     * @method b4DragDrop
     * @private
     */
    b4DragDrop: function(e) { },

    /**
     * Abstract method called when this item is dropped on another DragDrop 
     * obj
     * @method onDragDrop
     * @param {Event} e the mouseup event
     * @param {String|DragDrop[]} id In POINT mode, the element
     * id this was dropped on.  In INTERSECT mode, an array of dd items this 
     * was dropped on.
     */
    onDragDrop: function(e, id) { /* override this */ },

    /**
     * Abstract method called when this item is dropped on an area with no
     * drop target
     * @method onInvalidDrop
     * @param {Event} e the mouseup event
     */
    onInvalidDrop: function(e) { /* override this */ },

    /**
     * Code that executes immediately before the endDrag event
     * @method b4EndDrag
     * @private
     */
    b4EndDrag: function(e) { },

    /**
     * Fired when we are done dragging the object
     * @method endDrag
     * @param {Event} e the mouseup event
     */
    endDrag: function(e) { /* override this */ },

    /**
     * Code executed immediately before the onMouseDown event
     * @method b4MouseDown
     * @param {Event} e the mousedown event
     * @private
     */
    b4MouseDown: function(e) {  },

    /**
     * Event handler that fires when a drag/drop obj gets a mousedown
     * @method onMouseDown
     * @param {Event} e the mousedown event
     */
    onMouseDown: function(e) { /* override this */ },

    /**
     * Event handler that fires when a drag/drop obj gets a mouseup
     * @method onMouseUp
     * @param {Event} e the mouseup event
     */
    onMouseUp: function(e) { /* override this */ },
   
    /**
     * Override the onAvailable method to do what is needed after the initial
     * position was determined.
     * @method onAvailable
     */
    onAvailable: function () { 
    },

    /**
     * Returns a reference to the linked element
     * @method getEl
     * @return {HTMLElement} the html element 
     */
    getEl: function() { 
        if (!this._domRef) {
            this._domRef = Dom.get(this.id); 
        }

        return this._domRef;
    },

    /**
     * Returns a reference to the actual element to drag.  By default this is
     * the same as the html element, but it can be assigned to another 
     * element. An example of this can be found in YAHOO.util.DDProxy
     * @method getDragEl
     * @return {HTMLElement} the html element 
     */
    getDragEl: function() {
        return Dom.get(this.dragElId);
    },

    /**
     * Sets up the DragDrop object.  Must be called in the constructor of any
     * YAHOO.util.DragDrop subclass
     * @method init
     * @param id the id of the linked element
     * @param {String} sGroup the group of related items
     * @param {object} config configuration attributes
     */
    init: function(id, sGroup, config) {
        this.initTarget(id, sGroup, config);
        Event.on(this._domRef || this.id, "mousedown", 
                        this.handleMouseDown, this, true);

        // Event.on(this.id, "selectstart", Event.preventDefault);
        for (var i in this.events) {
            this.createEvent(i + 'Event');
        }
        
    },

    /**
     * Initializes Targeting functionality only... the object does not
     * get a mousedown handler.
     * @method initTarget
     * @param id the id of the linked element
     * @param {String} sGroup the group of related items
     * @param {object} config configuration attributes
     */
    initTarget: function(id, sGroup, config) {

        // configuration attributes 
        this.config = config || {};

        this.events = {};

        // create a local reference to the drag and drop manager
        this.DDM = YAHOO.util.DDM;

        // initialize the groups object
        this.groups = {};

        // assume that we have an element reference instead of an id if the
        // parameter is not a string
        if (typeof id !== "string") {
            this._domRef = id;
            id = Dom.generateId(id);
        }

        // set the id
        this.id = id;

        // add to an interaction group
        this.addToGroup((sGroup) ? sGroup : "default");

        // We don't want to register this as the handle with the manager
        // so we just set the id rather than calling the setter.
        this.handleElId = id;

        Event.onAvailable(id, this.handleOnAvailable, this, true);


        // the linked element is the element that gets dragged by default
        this.setDragElId(id); 

        // by default, clicked anchors will not start drag operations. 
        // @TODO what else should be here?  Probably form fields.
        this.invalidHandleTypes = { A: "A" };
        this.invalidHandleIds = {};
        this.invalidHandleClasses = [];

        this.applyConfig();
    },

    /**
     * Applies the configuration parameters that were passed into the constructor.
     * This is supposed to happen at each level through the inheritance chain.  So
     * a DDProxy implentation will execute apply config on DDProxy, DD, and 
     * DragDrop in order to get all of the parameters that are available in
     * each object.
     * @method applyConfig
     */
    applyConfig: function() {
        this.events = {
            mouseDown: true,
            b4MouseDown: true,
            mouseUp: true,
            b4StartDrag: true,
            startDrag: true,
            b4EndDrag: true,
            endDrag: true,
            drag: true,
            b4Drag: true,
            invalidDrop: true,
            b4DragOut: true,
            dragOut: true,
            dragEnter: true,
            b4DragOver: true,
            dragOver: true,
            b4DragDrop: true,
            dragDrop: true
        };
        
        if (this.config.events) {
            for (var i in this.config.events) {
                if (this.config.events[i] === false) {
                    this.events[i] = false;
                }
            }
        }


        // configurable properties: 
        //    padding, isTarget, maintainOffset, primaryButtonOnly
        this.padding           = this.config.padding || [0, 0, 0, 0];
        this.isTarget          = (this.config.isTarget !== false);
        this.maintainOffset    = (this.config.maintainOffset);
        this.primaryButtonOnly = (this.config.primaryButtonOnly !== false);
        this.dragOnly = ((this.config.dragOnly === true) ? true : false);
        this.useShim = ((this.config.useShim === true) ? true : false);
    },

    /**
     * Executed when the linked element is available
     * @method handleOnAvailable
     * @private
     */
    handleOnAvailable: function() {
        this.available = true;
        this.resetConstraints();
        this.onAvailable();
    },

     /**
     * Configures the padding for the target zone in px.  Effectively expands
     * (or reduces) the virtual object size for targeting calculations.  
     * Supports css-style shorthand; if only one parameter is passed, all sides
     * will have that padding, and if only two are passed, the top and bottom
     * will have the first param, the left and right the second.
     * @method setPadding
     * @param {int} iTop    Top pad
     * @param {int} iRight  Right pad
     * @param {int} iBot    Bot pad
     * @param {int} iLeft   Left pad
     */
    setPadding: function(iTop, iRight, iBot, iLeft) {
        // this.padding = [iLeft, iRight, iTop, iBot];
        if (!iRight && 0 !== iRight) {
            this.padding = [iTop, iTop, iTop, iTop];
        } else if (!iBot && 0 !== iBot) {
            this.padding = [iTop, iRight, iTop, iRight];
        } else {
            this.padding = [iTop, iRight, iBot, iLeft];
        }
    },

    /**
     * Stores the initial placement of the linked element.
     * @method setInitialPosition
     * @param {int} diffX   the X offset, default 0
     * @param {int} diffY   the Y offset, default 0
     * @private
     */
    setInitPosition: function(diffX, diffY) {
        var el = this.getEl();

        if (!this.DDM.verifyEl(el)) {
            if (el && el.style && (el.style.display == 'none')) {
            } else {
            }
            return;
        }

        var dx = diffX || 0;
        var dy = diffY || 0;

        var p = Dom.getXY( el );

        this.initPageX = p[0] - dx;
        this.initPageY = p[1] - dy;

        this.lastPageX = p[0];
        this.lastPageY = p[1];



        this.setStartPosition(p);
    },

    /**
     * Sets the start position of the element.  This is set when the obj
     * is initialized, the reset when a drag is started.
     * @method setStartPosition
     * @param pos current position (from previous lookup)
     * @private
     */
    setStartPosition: function(pos) {
        var p = pos || Dom.getXY(this.getEl());

        this.deltaSetXY = null;

        this.startPageX = p[0];
        this.startPageY = p[1];
    },

    /**
     * Add this instance to a group of related drag/drop objects.  All 
     * instances belong to at least one group, and can belong to as many 
     * groups as needed.
     * @method addToGroup
     * @param sGroup {string} the name of the group
     */
    addToGroup: function(sGroup) {
        this.groups[sGroup] = true;
        this.DDM.regDragDrop(this, sGroup);
    },

    /**
     * Remove's this instance from the supplied interaction group
     * @method removeFromGroup
     * @param {string}  sGroup  The group to drop
     */
    removeFromGroup: function(sGroup) {
        if (this.groups[sGroup]) {
            delete this.groups[sGroup];
        }

        this.DDM.removeDDFromGroup(this, sGroup);
    },

    /**
     * Allows you to specify that an element other than the linked element 
     * will be moved with the cursor during a drag
     * @method setDragElId
     * @param id {string} the id of the element that will be used to initiate the drag
     */
    setDragElId: function(id) {
        this.dragElId = id;
    },

    /**
     * Allows you to specify a child of the linked element that should be 
     * used to initiate the drag operation.  An example of this would be if 
     * you have a content div with text and links.  Clicking anywhere in the 
     * content area would normally start the drag operation.  Use this method
     * to specify that an element inside of the content div is the element 
     * that starts the drag operation.
     * @method setHandleElId
     * @param id {string} the id of the element that will be used to 
     * initiate the drag.
     */
    setHandleElId: function(id) {
        if (typeof id !== "string") {
            id = Dom.generateId(id);
        }
        this.handleElId = id;
        this.DDM.regHandle(this.id, id);
    },

    /**
     * Allows you to set an element outside of the linked element as a drag 
     * handle
     * @method setOuterHandleElId
     * @param id the id of the element that will be used to initiate the drag
     */
    setOuterHandleElId: function(id) {
        if (typeof id !== "string") {
            id = Dom.generateId(id);
        }
        Event.on(id, "mousedown", 
                this.handleMouseDown, this, true);
        this.setHandleElId(id);

        this.hasOuterHandles = true;
    },

    /**
     * Remove all drag and drop hooks for this element
     * @method unreg
     */
    unreg: function() {
        Event.removeListener(this.id, "mousedown", 
                this.handleMouseDown);
        this._domRef = null;
        this.DDM._remove(this);
    },

    /**
     * Returns true if this instance is locked, or the drag drop mgr is locked
     * (meaning that all drag/drop is disabled on the page.)
     * @method isLocked
     * @return {boolean} true if this obj or all drag/drop is locked, else 
     * false
     */
    isLocked: function() {
        return (this.DDM.isLocked() || this.locked);
    },

    /**
     * Fired when this object is clicked
     * @method handleMouseDown
     * @param {Event} e 
     * @param {YAHOO.util.DragDrop} oDD the clicked dd object (this dd obj)
     * @private
     */
    handleMouseDown: function(e, oDD) {

        var button = e.which || e.button;

        if (this.primaryButtonOnly && button > 1) {
            return;
        }

        if (this.isLocked()) {
            return;
        }



        // firing the mousedown events prior to calculating positions
        var b4Return = this.b4MouseDown(e),
        b4Return2 = true;

        if (this.events.b4MouseDown) {
            b4Return2 = this.fireEvent('b4MouseDownEvent', e);
        }
        var mDownReturn = this.onMouseDown(e),
            mDownReturn2 = true;
        if (this.events.mouseDown) {
            mDownReturn2 = this.fireEvent('mouseDownEvent', e);
        }

        if ((b4Return === false) || (mDownReturn === false) || (b4Return2 === false) || (mDownReturn2 === false)) {
            return;
        }

        this.DDM.refreshCache(this.groups);
        // var self = this;
        // setTimeout( function() { self.DDM.refreshCache(self.groups); }, 0);

        // Only process the event if we really clicked within the linked 
        // element.  The reason we make this check is that in the case that 
        // another element was moved between the clicked element and the 
        // cursor in the time between the mousedown and mouseup events. When 
        // this happens, the element gets the next mousedown event 
        // regardless of where on the screen it happened.  
        var pt = new YAHOO.util.Point(Event.getPageX(e), Event.getPageY(e));
        if (!this.hasOuterHandles && !this.DDM.isOverTarget(pt, this) )  {
        } else {
            if (this.clickValidator(e)) {


                // set the initial element position
                this.setStartPosition();

                // start tracking mousemove distance and mousedown time to
                // determine when to start the actual drag
                this.DDM.handleMouseDown(e, this);

                // this mousedown is mine
                this.DDM.stopEvent(e);
            } else {


            }
        }
    },

    /**
     * @method clickValidator
     * @description Method validates that the clicked element
     * was indeed the handle or a valid child of the handle
     * @param {Event} e 
     */
    clickValidator: function(e) {
        var target = YAHOO.util.Event.getTarget(e);
        return ( this.isValidHandleChild(target) &&
                    (this.id == this.handleElId || 
                        this.DDM.handleWasClicked(target, this.id)) );
    },

    /**
     * Finds the location the element should be placed if we want to move
     * it to where the mouse location less the click offset would place us.
     * @method getTargetCoord
     * @param {int} iPageX the X coordinate of the click
     * @param {int} iPageY the Y coordinate of the click
     * @return an object that contains the coordinates (Object.x and Object.y)
     * @private
     */
    getTargetCoord: function(iPageX, iPageY) {


        var x = iPageX - this.deltaX;
        var y = iPageY - this.deltaY;

        if (this.constrainX) {
            if (x < this.minX) { x = this.minX; }
            if (x > this.maxX) { x = this.maxX; }
        }

        if (this.constrainY) {
            if (y < this.minY) { y = this.minY; }
            if (y > this.maxY) { y = this.maxY; }
        }

        x = this.getTick(x, this.xTicks);
        y = this.getTick(y, this.yTicks);


        return {x:x, y:y};
    },

    /**
     * Allows you to specify a tag name that should not start a drag operation
     * when clicked.  This is designed to facilitate embedding links within a
     * drag handle that do something other than start the drag.
     * @method addInvalidHandleType
     * @param {string} tagName the type of element to exclude
     */
    addInvalidHandleType: function(tagName) {
        var type = tagName.toUpperCase();
        this.invalidHandleTypes[type] = type;
    },

    /**
     * Lets you to specify an element id for a child of a drag handle
     * that should not initiate a drag
     * @method addInvalidHandleId
     * @param {string} id the element id of the element you wish to ignore
     */
    addInvalidHandleId: function(id) {
        if (typeof id !== "string") {
            id = Dom.generateId(id);
        }
        this.invalidHandleIds[id] = id;
    },


    /**
     * Lets you specify a css class of elements that will not initiate a drag
     * @method addInvalidHandleClass
     * @param {string} cssClass the class of the elements you wish to ignore
     */
    addInvalidHandleClass: function(cssClass) {
        this.invalidHandleClasses.push(cssClass);
    },

    /**
     * Unsets an excluded tag name set by addInvalidHandleType
     * @method removeInvalidHandleType
     * @param {string} tagName the type of element to unexclude
     */
    removeInvalidHandleType: function(tagName) {
        var type = tagName.toUpperCase();
        // this.invalidHandleTypes[type] = null;
        delete this.invalidHandleTypes[type];
    },
    
    /**
     * Unsets an invalid handle id
     * @method removeInvalidHandleId
     * @param {string} id the id of the element to re-enable
     */
    removeInvalidHandleId: function(id) {
        if (typeof id !== "string") {
            id = Dom.generateId(id);
        }
        delete this.invalidHandleIds[id];
    },

    /**
     * Unsets an invalid css class
     * @method removeInvalidHandleClass
     * @param {string} cssClass the class of the element(s) you wish to 
     * re-enable
     */
    removeInvalidHandleClass: function(cssClass) {
        for (var i=0, len=this.invalidHandleClasses.length; i<len; ++i) {
            if (this.invalidHandleClasses[i] == cssClass) {
                delete this.invalidHandleClasses[i];
            }
        }
    },

    /**
     * Checks the tag exclusion list to see if this click should be ignored
     * @method isValidHandleChild
     * @param {HTMLElement} node the HTMLElement to evaluate
     * @return {boolean} true if this is a valid tag type, false if not
     */
    isValidHandleChild: function(node) {

        var valid = true;
        // var n = (node.nodeName == "#text") ? node.parentNode : node;
        var nodeName;
        try {
            nodeName = node.nodeName.toUpperCase();
        } catch(e) {
            nodeName = node.nodeName;
        }
        valid = valid && !this.invalidHandleTypes[nodeName];
        valid = valid && !this.invalidHandleIds[node.id];

        for (var i=0, len=this.invalidHandleClasses.length; valid && i<len; ++i) {
            valid = !Dom.hasClass(node, this.invalidHandleClasses[i]);
        }


        return valid;

    },

    /**
     * Create the array of horizontal tick marks if an interval was specified
     * in setXConstraint().
     * @method setXTicks
     * @private
     */
    setXTicks: function(iStartX, iTickSize) {
        this.xTicks = [];
        this.xTickSize = iTickSize;
        
        var tickMap = {};

        for (var i = this.initPageX; i >= this.minX; i = i - iTickSize) {
            if (!tickMap[i]) {
                this.xTicks[this.xTicks.length] = i;
                tickMap[i] = true;
            }
        }

        for (i = this.initPageX; i <= this.maxX; i = i + iTickSize) {
            if (!tickMap[i]) {
                this.xTicks[this.xTicks.length] = i;
                tickMap[i] = true;
            }
        }

        this.xTicks.sort(this.DDM.numericSort) ;
    },

    /**
     * Create the array of vertical tick marks if an interval was specified in 
     * setYConstraint().
     * @method setYTicks
     * @private
     */
    setYTicks: function(iStartY, iTickSize) {
        this.yTicks = [];
        this.yTickSize = iTickSize;

        var tickMap = {};

        for (var i = this.initPageY; i >= this.minY; i = i - iTickSize) {
            if (!tickMap[i]) {
                this.yTicks[this.yTicks.length] = i;
                tickMap[i] = true;
            }
        }

        for (i = this.initPageY; i <= this.maxY; i = i + iTickSize) {
            if (!tickMap[i]) {
                this.yTicks[this.yTicks.length] = i;
                tickMap[i] = true;
            }
        }

        this.yTicks.sort(this.DDM.numericSort) ;
    },

    /**
     * By default, the element can be dragged any place on the screen.  Use 
     * this method to limit the horizontal travel of the element.  Pass in 
     * 0,0 for the parameters if you want to lock the drag to the y axis.
     * @method setXConstraint
     * @param {int} iLeft the number of pixels the element can move to the left
     * @param {int} iRight the number of pixels the element can move to the 
     * right
     * @param {int} iTickSize optional parameter for specifying that the 
     * element
     * should move iTickSize pixels at a time.
     */
    setXConstraint: function(iLeft, iRight, iTickSize) {
        this.leftConstraint = parseInt(iLeft, 10);
        this.rightConstraint = parseInt(iRight, 10);

        this.minX = this.initPageX - this.leftConstraint;
        this.maxX = this.initPageX + this.rightConstraint;
        if (iTickSize) { this.setXTicks(this.initPageX, iTickSize); }

        this.constrainX = true;
    },

    /**
     * Clears any constraints applied to this instance.  Also clears ticks
     * since they can't exist independent of a constraint at this time.
     * @method clearConstraints
     */
    clearConstraints: function() {
        this.constrainX = false;
        this.constrainY = false;
        this.clearTicks();
    },

    /**
     * Clears any tick interval defined for this instance
     * @method clearTicks
     */
    clearTicks: function() {
        this.xTicks = null;
        this.yTicks = null;
        this.xTickSize = 0;
        this.yTickSize = 0;
    },

    /**
     * By default, the element can be dragged any place on the screen.  Set 
     * this to limit the vertical travel of the element.  Pass in 0,0 for the
     * parameters if you want to lock the drag to the x axis.
     * @method setYConstraint
     * @param {int} iUp the number of pixels the element can move up
     * @param {int} iDown the number of pixels the element can move down
     * @param {int} iTickSize optional parameter for specifying that the 
     * element should move iTickSize pixels at a time.
     */
    setYConstraint: function(iUp, iDown, iTickSize) {
        this.topConstraint = parseInt(iUp, 10);
        this.bottomConstraint = parseInt(iDown, 10);

        this.minY = this.initPageY - this.topConstraint;
        this.maxY = this.initPageY + this.bottomConstraint;
        if (iTickSize) { this.setYTicks(this.initPageY, iTickSize); }

        this.constrainY = true;
        
    },

    /**
     * resetConstraints must be called if you manually reposition a dd element.
     * @method resetConstraints
     */
    resetConstraints: function() {


        // Maintain offsets if necessary
        if (this.initPageX || this.initPageX === 0) {
            // figure out how much this thing has moved
            var dx = (this.maintainOffset) ? this.lastPageX - this.initPageX : 0;
            var dy = (this.maintainOffset) ? this.lastPageY - this.initPageY : 0;

            this.setInitPosition(dx, dy);

        // This is the first time we have detected the element's position
        } else {
            this.setInitPosition();
        }

        if (this.constrainX) {
            this.setXConstraint( this.leftConstraint, 
                                 this.rightConstraint, 
                                 this.xTickSize        );
        }

        if (this.constrainY) {
            this.setYConstraint( this.topConstraint, 
                                 this.bottomConstraint, 
                                 this.yTickSize         );
        }
    },

    /**
     * Normally the drag element is moved pixel by pixel, but we can specify 
     * that it move a number of pixels at a time.  This method resolves the 
     * location when we have it set up like this.
     * @method getTick
     * @param {int} val where we want to place the object
     * @param {int[]} tickArray sorted array of valid points
     * @return {int} the closest tick
     * @private
     */
    getTick: function(val, tickArray) {

        if (!tickArray) {
            // If tick interval is not defined, it is effectively 1 pixel, 
            // so we return the value passed to us.
            return val; 
        } else if (tickArray[0] >= val) {
            // The value is lower than the first tick, so we return the first
            // tick.
            return tickArray[0];
        } else {
            for (var i=0, len=tickArray.length; i<len; ++i) {
                var next = i + 1;
                if (tickArray[next] && tickArray[next] >= val) {
                    var diff1 = val - tickArray[i];
                    var diff2 = tickArray[next] - val;
                    return (diff2 > diff1) ? tickArray[i] : tickArray[next];
                }
            }

            // The value is larger than the last tick, so we return the last
            // tick.
            return tickArray[tickArray.length - 1];
        }
    },

    /**
     * toString method
     * @method toString
     * @return {string} string representation of the dd obj
     */
    toString: function() {
        return ("DragDrop " + this.id);
    }

};
YAHOO.augment(YAHOO.util.DragDrop, YAHOO.util.EventProvider);

/**
* @event mouseDownEvent
* @description Provides access to the mousedown event. The mousedown does not always result in a drag operation.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/

/**
* @event b4MouseDownEvent
* @description Provides access to the mousedown event, before the mouseDownEvent gets fired. Returning false will cancel the drag.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/

/**
* @event mouseUpEvent
* @description Fired from inside DragDropMgr when the drag operation is finished.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/

/**
* @event b4StartDragEvent
* @description Fires before the startDragEvent, returning false will cancel the startDrag Event.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/

/**
* @event startDragEvent
* @description Occurs after a mouse down and the drag threshold has been met. The drag threshold default is either 3 pixels of mouse movement or 1 full second of holding the mousedown. 
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/

/**
* @event b4EndDragEvent
* @description Fires before the endDragEvent. Returning false will cancel.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/

/**
* @event endDragEvent
* @description Fires on the mouseup event after a drag has been initiated (startDrag fired).
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/

/**
* @event dragEvent
* @description Occurs every mousemove event while dragging.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event b4DragEvent
* @description Fires before the dragEvent.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event invalidDropEvent
* @description Fires when the dragged objects is dropped in a location that contains no drop targets.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event b4DragOutEvent
* @description Fires before the dragOutEvent
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event dragOutEvent
* @description Fires when a dragged object is no longer over an object that had the onDragEnter fire. 
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event dragEnterEvent
* @description Occurs when the dragged object first interacts with another targettable drag and drop object.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event b4DragOverEvent
* @description Fires before the dragOverEvent.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event dragOverEvent
* @description Fires every mousemove event while over a drag and drop object.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event b4DragDropEvent 
* @description Fires before the dragDropEvent
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event dragDropEvent
* @description Fires when the dragged objects is dropped on another.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
})();
/**
 * A DragDrop implementation where the linked element follows the 
 * mouse cursor during a drag.
 * @class DD
 * @extends YAHOO.util.DragDrop
 * @namespace YAHOO.util
 * @constructor
 * @param {String} id the id of the linked element 
 * @param {String} sGroup the group of related DragDrop items
 * @param {object} config an object containing configurable attributes
 *                Valid properties for DD: 
 *                    scroll
 */
YAHOO.util.DD = function(id, sGroup, config) {
    if (id) {
        this.init(id, sGroup, config);
    }
};

YAHOO.extend(YAHOO.util.DD, YAHOO.util.DragDrop, {

    /**
     * When set to true, the utility automatically tries to scroll the browser
     * window when a drag and drop element is dragged near the viewport boundary.
     * Defaults to true.
     * @property scroll
     * @type boolean
     */
    scroll: true, 

    /**
     * Sets the pointer offset to the distance between the linked element's top 
     * left corner and the location the element was clicked
     * @method autoOffset
     * @param {int} iPageX the X coordinate of the click
     * @param {int} iPageY the Y coordinate of the click
     */
    autoOffset: function(iPageX, iPageY) {
        var x = iPageX - this.startPageX;
        var y = iPageY - this.startPageY;
        this.setDelta(x, y);
    },

    /** 
     * Sets the pointer offset.  You can call this directly to force the 
     * offset to be in a particular location (e.g., pass in 0,0 to set it 
     * to the center of the object, as done in YAHOO.widget.Slider)
     * @method setDelta
     * @param {int} iDeltaX the distance from the left
     * @param {int} iDeltaY the distance from the top
     */
    setDelta: function(iDeltaX, iDeltaY) {
        this.deltaX = iDeltaX;
        this.deltaY = iDeltaY;
    },

    /**
     * Sets the drag element to the location of the mousedown or click event, 
     * maintaining the cursor location relative to the location on the element 
     * that was clicked.  Override this if you want to place the element in a 
     * location other than where the cursor is.
     * @method setDragElPos
     * @param {int} iPageX the X coordinate of the mousedown or drag event
     * @param {int} iPageY the Y coordinate of the mousedown or drag event
     */
    setDragElPos: function(iPageX, iPageY) {
        // the first time we do this, we are going to check to make sure
        // the element has css positioning

        var el = this.getDragEl();
        this.alignElWithMouse(el, iPageX, iPageY);
    },

    /**
     * Sets the element to the location of the mousedown or click event, 
     * maintaining the cursor location relative to the location on the element 
     * that was clicked.  Override this if you want to place the element in a 
     * location other than where the cursor is.
     * @method alignElWithMouse
     * @param {HTMLElement} el the element to move
     * @param {int} iPageX the X coordinate of the mousedown or drag event
     * @param {int} iPageY the Y coordinate of the mousedown or drag event
     */
    alignElWithMouse: function(el, iPageX, iPageY) {
        var oCoord = this.getTargetCoord(iPageX, iPageY);

        if (!this.deltaSetXY) {
            var aCoord = [oCoord.x, oCoord.y];
            YAHOO.util.Dom.setXY(el, aCoord);

            var newLeft = parseInt( YAHOO.util.Dom.getStyle(el, "left"), 10 );
            var newTop  = parseInt( YAHOO.util.Dom.getStyle(el, "top" ), 10 );

            this.deltaSetXY = [ newLeft - oCoord.x, newTop - oCoord.y ];
        } else {
            YAHOO.util.Dom.setStyle(el, "left", (oCoord.x + this.deltaSetXY[0]) + "px");
            YAHOO.util.Dom.setStyle(el, "top",  (oCoord.y + this.deltaSetXY[1]) + "px");
        }
        
        this.cachePosition(oCoord.x, oCoord.y);
        var self = this;
        setTimeout(function() {
            self.autoScroll.call(self, oCoord.x, oCoord.y, el.offsetHeight, el.offsetWidth);
        }, 0);
    },

    /**
     * Saves the most recent position so that we can reset the constraints and
     * tick marks on-demand.  We need to know this so that we can calculate the
     * number of pixels the element is offset from its original position.
     * @method cachePosition
     * @param iPageX the current x position (optional, this just makes it so we
     * don't have to look it up again)
     * @param iPageY the current y position (optional, this just makes it so we
     * don't have to look it up again)
     */
    cachePosition: function(iPageX, iPageY) {
        if (iPageX) {
            this.lastPageX = iPageX;
            this.lastPageY = iPageY;
        } else {
            var aCoord = YAHOO.util.Dom.getXY(this.getEl());
            this.lastPageX = aCoord[0];
            this.lastPageY = aCoord[1];
        }
    },

    /**
     * Auto-scroll the window if the dragged object has been moved beyond the 
     * visible window boundary.
     * @method autoScroll
     * @param {int} x the drag element's x position
     * @param {int} y the drag element's y position
     * @param {int} h the height of the drag element
     * @param {int} w the width of the drag element
     * @private
     */
    autoScroll: function(x, y, h, w) {

        if (this.scroll) {
            // The client height
            var clientH = this.DDM.getClientHeight();

            // The client width
            var clientW = this.DDM.getClientWidth();

            // The amt scrolled down
            var st = this.DDM.getScrollTop();

            // The amt scrolled right
            var sl = this.DDM.getScrollLeft();

            // Location of the bottom of the element
            var bot = h + y;

            // Location of the right of the element
            var right = w + x;

            // The distance from the cursor to the bottom of the visible area, 
            // adjusted so that we don't scroll if the cursor is beyond the
            // element drag constraints
            var toBot = (clientH + st - y - this.deltaY);

            // The distance from the cursor to the right of the visible area
            var toRight = (clientW + sl - x - this.deltaX);


            // How close to the edge the cursor must be before we scroll
            // var thresh = (document.all) ? 100 : 40;
            var thresh = 40;

            // How many pixels to scroll per autoscroll op.  This helps to reduce 
            // clunky scrolling. IE is more sensitive about this ... it needs this 
            // value to be higher.
            var scrAmt = (document.all) ? 80 : 30;

            // Scroll down if we are near the bottom of the visible page and the 
            // obj extends below the crease
            if ( bot > clientH && toBot < thresh ) { 
                window.scrollTo(sl, st + scrAmt); 
            }

            // Scroll up if the window is scrolled down and the top of the object
            // goes above the top border
            if ( y < st && st > 0 && y - st < thresh ) { 
                window.scrollTo(sl, st - scrAmt); 
            }

            // Scroll right if the obj is beyond the right border and the cursor is
            // near the border.
            if ( right > clientW && toRight < thresh ) { 
                window.scrollTo(sl + scrAmt, st); 
            }

            // Scroll left if the window has been scrolled to the right and the obj
            // extends past the left border
            if ( x < sl && sl > 0 && x - sl < thresh ) { 
                window.scrollTo(sl - scrAmt, st);
            }
        }
    },

    /*
     * Sets up config options specific to this class. Overrides
     * YAHOO.util.DragDrop, but all versions of this method through the 
     * inheritance chain are called
     */
    applyConfig: function() {
        YAHOO.util.DD.superclass.applyConfig.call(this);
        this.scroll = (this.config.scroll !== false);
    },

    /*
     * Event that fires prior to the onMouseDown event.  Overrides 
     * YAHOO.util.DragDrop.
     */
    b4MouseDown: function(e) {
        this.setStartPosition();
        // this.resetConstraints();
        this.autoOffset(YAHOO.util.Event.getPageX(e), 
                            YAHOO.util.Event.getPageY(e));
    },

    /*
     * Event that fires prior to the onDrag event.  Overrides 
     * YAHOO.util.DragDrop.
     */
    b4Drag: function(e) {
        this.setDragElPos(YAHOO.util.Event.getPageX(e), 
                            YAHOO.util.Event.getPageY(e));
    },

    toString: function() {
        return ("DD " + this.id);
    }

    //////////////////////////////////////////////////////////////////////////
    // Debugging ygDragDrop events that can be overridden
    //////////////////////////////////////////////////////////////////////////
    /*
    startDrag: function(x, y) {
    },

    onDrag: function(e) {
    },

    onDragEnter: function(e, id) {
    },

    onDragOver: function(e, id) {
    },

    onDragOut: function(e, id) {
    },

    onDragDrop: function(e, id) {
    },

    endDrag: function(e) {
    }

    */

/**
* @event mouseDownEvent
* @description Provides access to the mousedown event. The mousedown does not always result in a drag operation.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/

/**
* @event b4MouseDownEvent
* @description Provides access to the mousedown event, before the mouseDownEvent gets fired. Returning false will cancel the drag.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/

/**
* @event mouseUpEvent
* @description Fired from inside DragDropMgr when the drag operation is finished.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/

/**
* @event b4StartDragEvent
* @description Fires before the startDragEvent, returning false will cancel the startDrag Event.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/

/**
* @event startDragEvent
* @description Occurs after a mouse down and the drag threshold has been met. The drag threshold default is either 3 pixels of mouse movement or 1 full second of holding the mousedown. 
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/

/**
* @event b4EndDragEvent
* @description Fires before the endDragEvent. Returning false will cancel.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/

/**
* @event endDragEvent
* @description Fires on the mouseup event after a drag has been initiated (startDrag fired).
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/

/**
* @event dragEvent
* @description Occurs every mousemove event while dragging.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event b4DragEvent
* @description Fires before the dragEvent.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event invalidDropEvent
* @description Fires when the dragged objects is dropped in a location that contains no drop targets.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event b4DragOutEvent
* @description Fires before the dragOutEvent
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event dragOutEvent
* @description Fires when a dragged object is no longer over an object that had the onDragEnter fire. 
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event dragEnterEvent
* @description Occurs when the dragged object first interacts with another targettable drag and drop object.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event b4DragOverEvent
* @description Fires before the dragOverEvent.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event dragOverEvent
* @description Fires every mousemove event while over a drag and drop object.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event b4DragDropEvent 
* @description Fires before the dragDropEvent
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event dragDropEvent
* @description Fires when the dragged objects is dropped on another.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
});
/**
 * A DragDrop implementation that inserts an empty, bordered div into
 * the document that follows the cursor during drag operations.  At the time of
 * the click, the frame div is resized to the dimensions of the linked html
 * element, and moved to the exact location of the linked element.
 *
 * References to the "frame" element refer to the single proxy element that
 * was created to be dragged in place of all DDProxy elements on the
 * page.
 *
 * @class DDProxy
 * @extends YAHOO.util.DD
 * @namespace YAHOO.util
 * @constructor
 * @param {String} id the id of the linked html element
 * @param {String} sGroup the group of related DragDrop objects
 * @param {object} config an object containing configurable attributes
 *                Valid properties for DDProxy in addition to those in DragDrop: 
 *                   resizeFrame, centerFrame, dragElId
 */
YAHOO.util.DDProxy = function(id, sGroup, config) {
    if (id) {
        this.init(id, sGroup, config);
        this.initFrame(); 
    }
};

/**
 * The default drag frame div id
 * @property YAHOO.util.DDProxy.dragElId
 * @type String
 * @static
 */
YAHOO.util.DDProxy.dragElId = "ygddfdiv";

YAHOO.extend(YAHOO.util.DDProxy, YAHOO.util.DD, {

    /**
     * By default we resize the drag frame to be the same size as the element
     * we want to drag (this is to get the frame effect).  We can turn it off
     * if we want a different behavior.
     * @property resizeFrame
     * @type boolean
     */
    resizeFrame: true,

    /**
     * By default the frame is positioned exactly where the drag element is, so
     * we use the cursor offset provided by YAHOO.util.DD.  Another option that works only if
     * you do not have constraints on the obj is to have the drag frame centered
     * around the cursor.  Set centerFrame to true for this effect.
     * @property centerFrame
     * @type boolean
     */
    centerFrame: false,

    /**
     * Creates the proxy element if it does not yet exist
     * @method createFrame
     */
    createFrame: function() {
        var self=this, body=document.body;

        if (!body || !body.firstChild) {
            setTimeout( function() { self.createFrame(); }, 50 );
            return;
        }

        var div=this.getDragEl(), Dom=YAHOO.util.Dom;

        if (!div) {
            div    = document.createElement("div");
            div.id = this.dragElId;
            var s  = div.style;

            s.position   = "absolute";
            s.visibility = "hidden";
            s.cursor     = "move";
            s.border     = "2px solid #aaa";
            s.zIndex     = 999;
            s.height     = "25px";
            s.width      = "25px";

            var _data = document.createElement('div');
            Dom.setStyle(_data, 'height', '100%');
            Dom.setStyle(_data, 'width', '100%');
            /**
            * If the proxy element has no background-color, then it is considered to the "transparent" by Internet Explorer.
            * Since it is "transparent" then the events pass through it to the iframe below.
            * So creating a "fake" div inside the proxy element and giving it a background-color, then setting it to an
            * opacity of 0, it appears to not be there, however IE still thinks that it is so the events never pass through.
            */
            Dom.setStyle(_data, 'background-color', '#ccc');
            Dom.setStyle(_data, 'opacity', '0');
            div.appendChild(_data);

            // appendChild can blow up IE if invoked prior to the window load event
            // while rendering a table.  It is possible there are other scenarios 
            // that would cause this to happen as well.
            body.insertBefore(div, body.firstChild);
        }
    },

    /**
     * Initialization for the drag frame element.  Must be called in the
     * constructor of all subclasses
     * @method initFrame
     */
    initFrame: function() {
        this.createFrame();
    },

    applyConfig: function() {
        YAHOO.util.DDProxy.superclass.applyConfig.call(this);

        this.resizeFrame = (this.config.resizeFrame !== false);
        this.centerFrame = (this.config.centerFrame);
        this.setDragElId(this.config.dragElId || YAHOO.util.DDProxy.dragElId);
    },

    /**
     * Resizes the drag frame to the dimensions of the clicked object, positions 
     * it over the object, and finally displays it
     * @method showFrame
     * @param {int} iPageX X click position
     * @param {int} iPageY Y click position
     * @private
     */
    showFrame: function(iPageX, iPageY) {
        var el = this.getEl();
        var dragEl = this.getDragEl();
        var s = dragEl.style;

        this._resizeProxy();

        if (this.centerFrame) {
            this.setDelta( Math.round(parseInt(s.width,  10)/2), 
                           Math.round(parseInt(s.height, 10)/2) );
        }

        this.setDragElPos(iPageX, iPageY);

        YAHOO.util.Dom.setStyle(dragEl, "visibility", "visible"); 
    },

    /**
     * The proxy is automatically resized to the dimensions of the linked
     * element when a drag is initiated, unless resizeFrame is set to false
     * @method _resizeProxy
     * @private
     */
    _resizeProxy: function() {
        if (this.resizeFrame) {
            var DOM    = YAHOO.util.Dom;
            var el     = this.getEl();
            var dragEl = this.getDragEl();

            var bt = parseInt( DOM.getStyle(dragEl, "borderTopWidth"    ), 10);
            var br = parseInt( DOM.getStyle(dragEl, "borderRightWidth"  ), 10);
            var bb = parseInt( DOM.getStyle(dragEl, "borderBottomWidth" ), 10);
            var bl = parseInt( DOM.getStyle(dragEl, "borderLeftWidth"   ), 10);

            if (isNaN(bt)) { bt = 0; }
            if (isNaN(br)) { br = 0; }
            if (isNaN(bb)) { bb = 0; }
            if (isNaN(bl)) { bl = 0; }


            var newWidth  = Math.max(0, el.offsetWidth  - br - bl);                                                                                           
            var newHeight = Math.max(0, el.offsetHeight - bt - bb);


            DOM.setStyle( dragEl, "width",  newWidth  + "px" );
            DOM.setStyle( dragEl, "height", newHeight + "px" );
        }
    },

    // overrides YAHOO.util.DragDrop
    b4MouseDown: function(e) {
        this.setStartPosition();
        var x = YAHOO.util.Event.getPageX(e);
        var y = YAHOO.util.Event.getPageY(e);
        this.autoOffset(x, y);

        // This causes the autoscroll code to kick off, which means autoscroll can
        // happen prior to the check for a valid drag handle.
        // this.setDragElPos(x, y);
    },

    // overrides YAHOO.util.DragDrop
    b4StartDrag: function(x, y) {
        // show the drag frame
        this.showFrame(x, y);
    },

    // overrides YAHOO.util.DragDrop
    b4EndDrag: function(e) {
        YAHOO.util.Dom.setStyle(this.getDragEl(), "visibility", "hidden"); 
    },

    // overrides YAHOO.util.DragDrop
    // By default we try to move the element to the last location of the frame.  
    // This is so that the default behavior mirrors that of YAHOO.util.DD.  
    endDrag: function(e) {
        var DOM = YAHOO.util.Dom;
        var lel = this.getEl();
        var del = this.getDragEl();

        // Show the drag frame briefly so we can get its position
        // del.style.visibility = "";
        DOM.setStyle(del, "visibility", ""); 

        // Hide the linked element before the move to get around a Safari 
        // rendering bug.
        //lel.style.visibility = "hidden";
        DOM.setStyle(lel, "visibility", "hidden"); 
        YAHOO.util.DDM.moveToEl(lel, del);
        //del.style.visibility = "hidden";
        DOM.setStyle(del, "visibility", "hidden"); 
        //lel.style.visibility = "";
        DOM.setStyle(lel, "visibility", ""); 
    },

    toString: function() {
        return ("DDProxy " + this.id);
    }
/**
* @event mouseDownEvent
* @description Provides access to the mousedown event. The mousedown does not always result in a drag operation.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/

/**
* @event b4MouseDownEvent
* @description Provides access to the mousedown event, before the mouseDownEvent gets fired. Returning false will cancel the drag.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/

/**
* @event mouseUpEvent
* @description Fired from inside DragDropMgr when the drag operation is finished.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/

/**
* @event b4StartDragEvent
* @description Fires before the startDragEvent, returning false will cancel the startDrag Event.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/

/**
* @event startDragEvent
* @description Occurs after a mouse down and the drag threshold has been met. The drag threshold default is either 3 pixels of mouse movement or 1 full second of holding the mousedown. 
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/

/**
* @event b4EndDragEvent
* @description Fires before the endDragEvent. Returning false will cancel.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/

/**
* @event endDragEvent
* @description Fires on the mouseup event after a drag has been initiated (startDrag fired).
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/

/**
* @event dragEvent
* @description Occurs every mousemove event while dragging.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event b4DragEvent
* @description Fires before the dragEvent.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event invalidDropEvent
* @description Fires when the dragged objects is dropped in a location that contains no drop targets.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event b4DragOutEvent
* @description Fires before the dragOutEvent
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event dragOutEvent
* @description Fires when a dragged object is no longer over an object that had the onDragEnter fire. 
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event dragEnterEvent
* @description Occurs when the dragged object first interacts with another targettable drag and drop object.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event b4DragOverEvent
* @description Fires before the dragOverEvent.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event dragOverEvent
* @description Fires every mousemove event while over a drag and drop object.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event b4DragDropEvent 
* @description Fires before the dragDropEvent
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/
/**
* @event dragDropEvent
* @description Fires when the dragged objects is dropped on another.
* @type YAHOO.util.CustomEvent See <a href="YAHOO.util.Element.html#addListener">Element.addListener</a> for more information on listening for this event.
*/

});
/**
 * A DragDrop implementation that does not move, but can be a drop 
 * target.  You would get the same result by simply omitting implementation 
 * for the event callbacks, but this way we reduce the processing cost of the 
 * event listener and the callbacks.
 * @class DDTarget
 * @extends YAHOO.util.DragDrop 
 * @namespace YAHOO.util
 * @constructor
 * @param {String} id the id of the element that is a drop target
 * @param {String} sGroup the group of related DragDrop objects
 * @param {object} config an object containing configurable attributes
 *                 Valid properties for DDTarget in addition to those in 
 *                 DragDrop: 
 *                    none
 */
YAHOO.util.DDTarget = function(id, sGroup, config) {
    if (id) {
        this.initTarget(id, sGroup, config);
    }
};

// YAHOO.util.DDTarget.prototype = new YAHOO.util.DragDrop();
YAHOO.extend(YAHOO.util.DDTarget, YAHOO.util.DragDrop, {
    toString: function() {
        return ("DDTarget " + this.id);
    }
});
YAHOO.register("dragdrop", YAHOO.util.DragDropMgr, {version: "@VERSION@", build: "@BUILD@"});