source: Dev/trunk/src/client/dojo/dnd/Manager.js

define([
        "../_base/array",  "../_base/declare", "../_base/lang", "../_base/window",
        "../dom-class", "../Evented", "../has", "../keys", "../on", "../topic", "../touch",
        "./common", "./autoscroll", "./Avatar"
], function(array, declare, lang, win, domClass, Evented, has, keys, on, topic, touch,
        dnd, autoscroll, Avatar){

// module:
//              dojo/dnd/Manager

var Manager = declare("dojo.dnd.Manager", [Evented], {
        // summary:
        //              the manager of DnD operations (usually a singleton)
        constructor: function(){
                this.avatar  = null;
                this.source = null;
                this.nodes = [];
                this.copy  = true;
                this.target = null;
                this.canDropFlag = false;
                this.events = [];
        },

        // avatar's offset from the mouse
        OFFSET_X: has("touch") ? 0 : 16,
        OFFSET_Y: has("touch") ? -64 : 16,

        // methods
        overSource: function(source){
                // summary:
                //              called when a source detected a mouse-over condition
                // source: Object
                //              the reporter
                if(this.avatar){
                        this.target = (source && source.targetState != "Disabled") ? source : null;
                        this.canDropFlag = Boolean(this.target);
                        this.avatar.update();
                }
                topic.publish("/dnd/source/over", source);
        },
        outSource: function(source){
                // summary:
                //              called when a source detected a mouse-out condition
                // source: Object
                //              the reporter
                if(this.avatar){
                        if(this.target == source){
                                this.target = null;
                                this.canDropFlag = false;
                                this.avatar.update();
                                topic.publish("/dnd/source/over", null);
                        }
                }else{
                        topic.publish("/dnd/source/over", null);
                }
        },
        startDrag: function(source, nodes, copy){
                // summary:
                //              called to initiate the DnD operation
                // source: Object
                //              the source which provides items
                // nodes: Array
                //              the list of transferred items
                // copy: Boolean
                //              copy items, if true, move items otherwise

                // Tell autoscroll that a drag is starting
                autoscroll.autoScrollStart(win.doc);

                this.source = source;
                this.nodes  = nodes;
                this.copy   = Boolean(copy); // normalizing to true boolean
                this.avatar = this.makeAvatar();
                win.body().appendChild(this.avatar.node);
                topic.publish("/dnd/start", source, nodes, this.copy);

                function stopEvent(e){
                        e.preventDefault();
                        e.stopPropagation();
                }

                this.events = [
                        on(win.doc, touch.move, lang.hitch(this, "onMouseMove")),
                        on(win.doc, touch.release,   lang.hitch(this, "onMouseUp")),
                        on(win.doc, "keydown",   lang.hitch(this, "onKeyDown")),
                        on(win.doc, "keyup",     lang.hitch(this, "onKeyUp")),

                        // cancel text selection and text dragging
                        on(win.doc, "dragstart",   stopEvent),
                        on(win.body(), "selectstart", stopEvent)
                ];
                var c = "dojoDnd" + (copy ? "Copy" : "Move");
                domClass.add(win.body(), c);
        },
        canDrop: function(flag){
                // summary:
                //              called to notify if the current target can accept items
                var canDropFlag = Boolean(this.target && flag);
                if(this.canDropFlag != canDropFlag){
                        this.canDropFlag = canDropFlag;
                        this.avatar.update();
                }
        },
        stopDrag: function(){
                // summary:
                //              stop the DnD in progress
                domClass.remove(win.body(), ["dojoDndCopy", "dojoDndMove"]);
                array.forEach(this.events, function(handle){ handle.remove(); });
                this.events = [];
                this.avatar.destroy();
                this.avatar = null;
                this.source = this.target = null;
                this.nodes = [];
        },
        makeAvatar: function(){
                // summary:
                //              makes the avatar; it is separate to be overwritten dynamically, if needed
                return new Avatar(this);
        },
        updateAvatar: function(){
                // summary:
                //              updates the avatar; it is separate to be overwritten dynamically, if needed
                this.avatar.update();
        },

        // mouse event processors
        onMouseMove: function(e){
                // summary:
                //              event processor for onmousemove
                // e: Event
                //              mouse event
                var a = this.avatar;
                if(a){
                        autoscroll.autoScrollNodes(e);
                        //autoscroll.autoScroll(e);
                        var s = a.node.style;
                        s.left = (e.pageX + this.OFFSET_X) + "px";
                        s.top  = (e.pageY + this.OFFSET_Y) + "px";
                        var copy = Boolean(this.source.copyState(dnd.getCopyKeyState(e)));
                        if(this.copy != copy){
                                this._setCopyStatus(copy);
                        }
                }
                if(has("touch")){
                        // Prevent page from scrolling so that user can drag instead.
                        e.preventDefault();
                }
        },
        onMouseUp: function(e){
                // summary:
                //              event processor for onmouseup
                // e: Event
                //              mouse event
                if(this.avatar){
                        if(this.target && this.canDropFlag){
                                var copy = Boolean(this.source.copyState(dnd.getCopyKeyState(e)));
                                topic.publish("/dnd/drop/before", this.source, this.nodes, copy, this.target, e);
                                topic.publish("/dnd/drop", this.source, this.nodes, copy, this.target, e);
                        }else{
                                topic.publish("/dnd/cancel");
                        }
                        this.stopDrag();
                }
        },

        // keyboard event processors
        onKeyDown: function(e){
                // summary:
                //              event processor for onkeydown:
                //              watching for CTRL for copy/move status, watching for ESCAPE to cancel the drag
                // e: Event
                //              keyboard event
                if(this.avatar){
                        switch(e.keyCode){
                                case keys.CTRL:
                                        var copy = Boolean(this.source.copyState(true));
                                        if(this.copy != copy){
                                                this._setCopyStatus(copy);
                                        }
                                        break;
                                case keys.ESCAPE:
                                        topic.publish("/dnd/cancel");
                                        this.stopDrag();
                                        break;
                        }
                }
        },
        onKeyUp: function(e){
                // summary:
                //              event processor for onkeyup, watching for CTRL for copy/move status
                // e: Event
                //              keyboard event
                if(this.avatar && e.keyCode == keys.CTRL){
                        var copy = Boolean(this.source.copyState(false));
                        if(this.copy != copy){
                                this._setCopyStatus(copy);
                        }
                }
        },

        // utilities
        _setCopyStatus: function(copy){
                // summary:
                //              changes the copy status
                // copy: Boolean
                //              the copy status
                this.copy = copy;
                this.source._markDndStatus(this.copy);
                this.updateAvatar();
                domClass.replace(win.body(),
                        "dojoDnd" + (this.copy ? "Copy" : "Move"),
                        "dojoDnd" + (this.copy ? "Move" : "Copy"));
        }
});

// dnd._manager:
//              The manager singleton variable. Can be overwritten if needed.
dnd._manager = null;

Manager.manager = dnd.manager = function(){
        // summary:
        //              Returns the current DnD manager.  Creates one if it is not created yet.
        if(!dnd._manager){
                dnd._manager = new Manager();
        }
        return dnd._manager;    // Object
};

// TODO: for 2.0, store _manager and manager in Manager only.   Don't access dnd or dojo.dnd.

return Manager;
});