dragdrop.js

这是YUI的源码及相关示例。里面有很多很炫的Javascript效果。

         * @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