dragdrop.js

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     * have helper methods that could be useful in your DragDrop
     * implementations.  This class should not be instantiated; all methods
     * are are static.
     *
     * @constructor
     */
    YAHOO.util.DragDropMgr = new function() {

        /**
         * utility package shorthand
         * @private
         */
        var UTIL = YAHOO.util;

        /**
         * Two dimensional Array of registered DragDrop objects.  The first
         * dimension is the DragDrop item group, the second the DragDrop
         * object.
         *
         * @private
         */
        this.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.
         *
         * @private
         */
        this.handleIds = {};

        /**
         * the DragDrop object that is currently being dragged
         *
         * @type DragDrop
         * @private
         **/
        this.dragCurrent = null;

        /**
         * the DragDrop object(s) that are being hovered over
         *
         * @type Array
         * @private
         */
        this.dragOvers = {};

        /**
         * @private
         */

        /**
         * the X distance between the cursor and the object being dragged
         *
         * @type int
         * @private
         */
        this.deltaX = 0;

        /**
         * the Y distance between the cursor and the object being dragged
         *
         * @type int
         * @private
         */
        this.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)
         *
         * @type boolean
         */
        this.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.
         *
         * @type boolean
         */
        this.stopPropagation = true;

        /**
         * @private
         */
        this.initalized = false;

        /**
         * All drag and drop can be disabled.
         *
         * @private
         */
        this.locked = false;

        /**
         * Called the first time an element is registered.
         *
         * @private
         */
        this.init = function() {
        };

        /**
         * In point mode, drag and drop interaction is defined by the
         * location of the cursor during the drag/drop
         * @type int
         */
        this.POINT     = 0;

        /**
         * In intersect mode, drag and drop interactio nis defined by the
         * overlap of two or more drag and drop objects.
         * @type int
         */
        this.INTERSECT = 1;

        /**
         * The current drag and drop mode.  Default it point mode
         * @type int
         */
        this.mode = this.POINT;

        /**
         * Runs method on all drag and drop objects
         * @private
         */
        this._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
         * @private
         */
        this._onLoad = function() {

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


            var EU = UTIL.Event;

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

            this.initalized = true;

        };

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

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

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

        /**
         * Is drag and drop locked?
         *
         * @return {boolean} True if drag and drop is locked, false otherwise.
         */
        this.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.
         *
         * @private
         */
        this.locationCache = {};

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

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

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

        /**
         * Flag that indicates that either the drag pixel threshold or the
         * mousdown time threshold has been met
         * @type boolean
         * @private
         */
        this.dragThreshMet = false;

        /**
         * Timeout used for the click time threshold
         * @type Object
         * @private
         */
        this.clickTimeout = null;

        /**
         * The X position of the mousedown event stored for later use when a
         * drag threshold is met.
         * @type int
         * @private
         */
        this.startX = 0;

        /**
         * The Y position of the mousedown event stored for later use when a
         * drag threshold is met.
         * @type int
         * @private
         */
        this.startY = 0;

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

            if (!this.ids[sGroup]) {
                this.ids[sGroup] = {};
            }
            this.ids[sGroup][oDD.id] = oDD;
        };

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

        /**
         * Each DragDrop handle element must be registered.  This is done
         * automatically when executing ygDragDrop.setHandleElId()
         *
         * @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
         */
        this.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.
         *
         * @param {String} id the element id to check
         * @return {boolean} true if this element is a DragDrop item,
         * false otherwise
         */
        this.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.
         *
         * @param {ygDragDrop} p_oDD the obj to get related data for
         * @param {boolean} bTargetsOnly if true, only return targetable objs
         * @return {ygDragDrop[]} the related instances
         */
        this.getRelated = function(p_oDD, bTargetsOnly) {
            var oDDs = [];
            for (var i in p_oDD.groups) {
                for (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
         *
         * @param {ygDragDrop} the drag obj
         * @param {ygDragDrop) the target
         * @return {boolean} true if the target is a legal target for the
         * dd obj
         */
        this.isLegalTarget = function (oDD, oTargetDD) {
            var targets = this.getRelated(oDD);
            for (var i =0;i<targets.length;++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 ygDragDrop, and the exact subclass of ygDragDrop.  typeof
         * returns "object", oDD.constructor.toString() always returns
         * "ygDragDrop" and not the name of the subclass.  So for now it just
         * evaluates a well-known variable in ygDragDrop.
         *
         * @param {Object} the object to evaluate
         * @return {boolean} true if typeof oDD = ygDragDrop
         */
        this.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.
         *
         * @param {String} id the element id to check
         * @return {boolean} true if this element is a DragDrop handle, false
         * otherwise
         */
        this.isHandle = function(sDDId, sHandleId) {
            return ( this.handleIds[sDDId] &&
                            this.handleIds[sDDId][sHandleId] );
        };

        /**
         * Returns the DragDrop instance for a given id
         *
         * @param {String} id the id of the DragDrop object
         * @return {DragDrop} the drag drop object, null if it is not found
         */
        this.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
         *
         * @param {Event} e the event
         * @param oDD the DragDrop object being dragged
         * @private
         */
        this.handleMouseDown = function(e, oDD) {
            this.dragCurrent = oDD;

            var el = oDD.getEl();

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

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

            this.dragThreshMet = false;

            this.clickTimeout = setTimeout(
               "var DDM=YAHOO.util.DDM;DDM.startDrag(DDM.startX, DDM.startY)",
               this.clickTimeThresh );
        };

        /**
         * Fired when either the drag pixel threshol or the mousedown hold
         * time threshold has been met.
         *
         * @param x {int} the X position of the original mousedown
         * @param y {int} the Y position of the original mousedown
         */
        this.startDrag = function(x, y) {
            clearTimeout(this.clickTimeout);