dragdrop.js

这是YUI的源码及相关示例。里面有很多很炫的Javascript效果。

         * 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 mouseup outside of page boundary
                if (YAHOO.util.Event.isIE && !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