# Yahoo! UI Library

### dd 3.0.0

Yahoo! UI Library > dd > ddm-base.js (source view)
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        /**
         * Provides the base Drag Drop Manger required for making a Node draggable.
         * @module dd
         * @submodule dd-ddm-base
         */
         /**
         * Provides the base Drag Drop Manger required for making a Node draggable.
         * @class DDM
         * @extends Base
         * @constructor
         * @namespace DD
         */

        var DDMBase = function() {
            DDMBase.superclass.constructor.apply(this, arguments);
        };

        DDMBase.NAME = 'ddm';

        DDMBase.ATTRS = {
            /**
            * @attribute dragCursor
            * @description The cursor to apply when dragging, if shimmed the shim will get the cursor.
            * @type String
            */
            dragCursor: {
                value: 'move'
            },
            /**
            * @attribute clickPixelThresh
            * @description The number of pixels to move to start a drag operation, default is 3.
            * @type Number
            */
            clickPixelThresh: {
                value: 3
            },
            /**
            * @attribute clickTimeThresh
            * @description The number of milliseconds a mousedown has to pass to start a drag operation, default is 1000.
            * @type Number
            */
            clickTimeThresh: {
                value: 1000
            },
            /**
            * @attribute dragMode
            * @description This attribute only works if the dd-drop module is active. It will set the dragMode (point, intersect, strict) of all future Drag instances.
            * @type String
            */
            dragMode: {
                value: 'point',
                setter: function(mode) {
                    this._setDragMode(mode);
                    return mode;
                }
            }

        };

        Y.extend(DDMBase, Y.Base, {
            /**
            * @property _active
            * @description flag set when we activate our first drag, so DDM can start listening for events.
            * @type {Boolean}
            */
            _active: null,
            /**
            * @private
            * @method _setDragMode
            * @description Handler for dragMode attribute setter.
            * @param String/Number The Number value or the String for the DragMode to default all future drag instances to.
            * @return Number The Mode to be set
            */
            _setDragMode: function(mode) {
                if (mode === null) {
                    mode = Y.DD.DDM.get('dragMode');
                }
                switch (mode) {
                    case 1:
                    case 'intersect':
                        return 1;
                    case 2:
                    case 'strict':
                        return 2;
                    case 0:
                    case 'point':
                        return 0;
                }
                return 0;
            },
            /**
            * @property CSS_PREFIX
            * @description The PREFIX to attach to all DD CSS class names
            * @type {String}
            */
            CSS_PREFIX: 'yui-dd',
            _activateTargets: function() {},
            /**
            * @private
            * @property _drags
            * @description Holder for all registered drag elements.
            * @type {Array}
            */
            _drags: [],
            /**
            * @property activeDrag
            * @description A reference to the currently active draggable object.
            * @type {Drag}
            */
            activeDrag: false,
            /**
            * @private
            * @method _regDrag
            * @description Adds a reference to the drag object to the DDM._drags array, called in the constructor of Drag.
            * @param {Drag} d The Drag object
            */
            _regDrag: function(d) {
                if (this.getDrag(d.get('node'))) {
                    return false;
                }

                if (!this._active) {
                    this._setupListeners();
                }
                this._drags.push(d);
                return true;
            },
            /**
            * @private
            * @method _unregDrag
            * @description Remove this drag object from the DDM._drags array.
            * @param {Drag} d The drag object.
            */
            _unregDrag: function(d) {
                var tmp = [];
                Y.each(this._drags, function(n, i) {
                    if (n !== d) {
                        tmp[tmp.length] = n;
                    }
                });
                this._drags = tmp;
            },
            /**
            * @private
            * @method _setupListeners
            * @description Add the document listeners.
            */
            _setupListeners: function() {
                this._active = true;
                var doc = Y.get(document);
                doc.on('mousemove', Y.bind(this._move, this));
                //Y.Event.nativeAdd(document, 'mousemove', Y.bind(this._move, this));
                doc.on('mouseup', Y.bind(this._end, this));
            },
            /**
            * @private
            * @method _start
            * @description Internal method used by Drag to signal the start of a drag operation
            */
            _start: function() {
                this.fire('ddm:start');
                this._startDrag();
            },
            /**
            * @private
            * @method _startDrag
            * @description Factory method to be overwritten by other DDM's
            * @param {Number} x The x position of the drag element
            * @param {Number} y The y position of the drag element
            * @param {Number} w The width of the drag element
            * @param {Number} h The height of the drag element
            */
            _startDrag: function() {},
            /**
            * @private
            * @method _endDrag
            * @description Factory method to be overwritten by other DDM's
            */
            _endDrag: function() {},
            _dropMove: function() {},
            /**
            * @private
            * @method _end
            * @description Internal method used by Drag to signal the end of a drag operation
            */
            _end: function() {
                if (this.activeDrag) {
                    this._endDrag();
                    this.fire('ddm:end');
                    this.activeDrag.end.call(this.activeDrag);
                    this.activeDrag = null;
                }
            },
            /**
            * @method stopDrag
            * @description Method will forcefully stop a drag operation. For example calling this from inside an ESC keypress handler will stop this drag.
            * @return {Self}
            * @chainable
            */
            stopDrag: function() {
                if (this.activeDrag) {
                    this._end();
                }
                return this;
            },
            /**
            * @private
            * @method _move
            * @description Internal listener for the mousemove DOM event to pass to the Drag's move method.
            * @param {Event.Facade} ev The Dom mousemove Event
            */
            _move: function(ev) {
                if (this.activeDrag) {
                    this.activeDrag._move.call(this.activeDrag, ev);
                    this._dropMove();
                }
            },
            /**
            * //TODO Private, rename??...
            * @private
            * @method cssSizestoObject
            * @description Helper method to use to set the gutter from the attribute setter.
            * @param {String} gutter CSS style string for gutter: '5 0' (sets top and bottom to 5px, left and right to 0px), '1 2 3 4' (top 1px, right 2px, bottom 3px, left 4px)
            * @return {Object} The gutter Object Literal.
            */
            cssSizestoObject: function(gutter) {
                var x = gutter.split(' ');

                switch (x.length) {
                    case 1: x[1] = x[2] = x[3] = x[0]; break;
                    case 2: x[2] = x[0]; x[3] = x[1]; break;
                    case 3: x[3] = x[1]; break;
                }

                return {
                    top   : parseInt(x[0],10),
                    right : parseInt(x[1],10),
                    bottom: parseInt(x[2],10),
                    left  : parseInt(x[3],10)
                };
            },
            /**
            * @method getDrag
            * @description Get a valid Drag instance back from a Node or a selector string, false otherwise
            * @param {String/Object} node The Node instance or Selector string to check for a valid Drag Object
            * @return {Object}
            */
            getDrag: function(node) {
                var drag = false,
                    n = Y.get(node);
                if (n instanceof Y.Node) {
                    Y.each(this._drags, function(v, k) {
                        if (n.compareTo(v.get('node'))) {
                            drag = v;
                        }
                    });
                }
                return drag;
            }
        });

        Y.namespace('DD');
        Y.DD.DDM = new DDMBase();

        /**
        * @event ddm:start
        * @description Fires from the DDM before all drag events fire.
        * @type {Event.Custom}
        */
        /**
        * @event ddm:end
        * @description Fires from the DDM after the DDM finishes, before the drag end events.
        * @type {Event.Custom}
        */

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