# Yahoo! UI Library

### Drag and Drop 2.8.0r4

Yahoo! UI Library > dragdrop > YAHOO.util.DragDropMgr
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## `static` Class YAHOO.util.DragDropMgr

DragDropMgr is a singleton that tracks the element interaction for all DragDrop items in the window. Generally, you will not call this class directly, but it does have helper methods that could be useful in your DragDrop implementations.

### Properties

#### _debugShim - `private static Boolean`

This property is used when useShim is set to true, it will set the opacity on the shim to .5 for debugging. Use: (YAHOO.util.DDM._debugShim = true;)

#### _shim - `private static HTMLElement`

The HTML element created to use as a shim over the document to track mouse movements

#### _shimActive - `private static Boolean`

This property is used to determine if the shim is active over the screen, default false.

#### _shimState - `private static Boolean`

This property is used when useShim is set on a DragDrop object to store the current state of DDM.useShim so it can be reset when a drag operation is done.

#### _timeoutCount - `private static object`

Internal counter

#### clickPixelThresh - `static int`

The number of pixels that the mouse needs to move after the mousedown before the drag is initiated. Default=3;

#### clickTimeout - `private static Object`

Timeout used for the click time threshold

#### clickTimeThresh - `static int`

The number of milliseconds after the mousedown event to initiate the drag if we don't get a mouseup event. Default=1000

#### deltaX - `private static int`

the X distance between the cursor and the object being dragged

#### deltaY - `private static int`

the Y distance between the cursor and the object being dragged

#### dragCurrent - `private static DragDrop`

the DragDrop object that is currently being dragged

#### dragOvers - `private static Array`

the DragDrop object(s) that are being hovered over

#### dragThreshMet - `private static boolean`

Flag that indicates that either the drag pixel threshold or the mousdown time threshold has been met

#### elementCache - `private static object`

A cache of DOM elements
Deprecated: elements are not cached now

#### fromTimeout - `private static boolean`

Flag to determine if the drag event was fired from the click timeout and not the mouse move threshold.

#### handleIds - `private static {string: string}`

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.

#### ids - `private static {string: string}`

Two dimensional Array of registered DragDrop objects. The first dimension is the DragDrop item group, the second the DragDrop object.

#### initialized - `private static object`

Internal flag that is set to true when drag and drop has been initialized

#### interactionInfo - `static object`

Provides additional information about the the current set of interactions. Can be accessed from the event handlers. It contains the following properties: out: onDragOut interactions enter: onDragEnter interactions over: onDragOver interactions drop: onDragDrop interactions point: The location of the cursor draggedRegion: The location of dragged element at the time of the interaction sourceRegion: The location of the source elemtn at the time of the interaction validDrop: boolean

#### INTERSECT - `static final int`

In intersect mode, drag and drop interaction is defined by the cursor position or the amount of overlap of two or more drag and drop objects.

#### locationCache - `private static object`

Location cache that is set for all drag drop objects when a drag is initiated, cleared when the drag is finished.

#### locked - `private static object`

All drag and drop can be disabled.

#### mode - `static int`

The current drag and drop mode. Default: POINT

#### POINT - `static final int`

In point mode, drag and drop interaction is defined by the location of the cursor during the drag/drop

#### preventDefault - `static boolean`

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)

#### startX - `private static int`

The X position of the mousedown event stored for later use when a drag threshold is met.

#### startY - `private static int`

The Y position of the mousedown event stored for later use when a drag threshold is met.

#### stopPropagation - `static boolean`

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.

#### STRICT_INTERSECT - `static final int`

In intersect mode, drag and drop interaction is defined only by the overlap of two or more drag and drop objects.

#### useCache - `static boolean`

Set useCache to false if you want to force object the lookup of each drag and drop linked element constantly during a drag.

#### useShim - `static Boolean`

This property is used to turn on global use of the shim element on all DragDrop instances, defaults to false for backcompat. (Use: YAHOO.util.DDM.useShim = true)

### Methods

#### _activateShim

`private static void _activateShim ( )`
This method will create the shim element if needed, then show the shim element, size the element and set the _shimActive property to true

Returns: `void`

#### _addListeners

`private static void _addListeners ( )`
Trying to make the load order less important. Without this we get an error if this file is loaded before the Event Utility.

Returns: `void`

#### _deactivateShim

`private static void _deactivateShim ( )`
This method will hide the shim element and set the _shimActive property to false

Returns: `void`

#### _execOnAll

`private static void _execOnAll ( )`
Runs method on all drag and drop objects

Returns: `void`

#### _onLoad

`private static void _onLoad ( )`
Drag and drop initialization. Sets up the global event handlers

Returns: `void`

#### _onResize

`private static void _onResize ( )`
Reset constraints on all drag and drop objs

Returns: `void`

#### _onUnload

`private static void _onUnload ( )`
unload event handler

Returns: `void`

#### _remove

`private static void _remove ( )`
Unregisters a drag and drop item. This is executed in DragDrop.unreg, use that method instead of calling this directly.

Returns: `void`

#### _sizeShim

`private static void _sizeShim ( )`
This method will create a shim element (giving it the id of yui-ddm-shim), it also attaches the mousemove and mouseup listeners to it and attaches a scroll listener on the window

Returns: `void`

#### fireEvents

`private static void fireEvents ( e , isDrop )`
Iterates over all of the DragDrop elements to find ones we are hovering over or dropping on

Parameters:
  `e <Event>` the event
  `isDrop <boolean>` is this a drop op or a mouseover op?

Returns: `void`

#### getBestMatch

`static DragDrop getBestMatch ( dds )`
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.

Parameters:
  `dds <DragDrop[]>` The array of drag and drop objects targeted

Returns: `DragDrop`
  The best single match

#### getClientHeight

`static int getClientHeight ( )`
Gets the client height

Returns: `int`
  client height in px

Deprecated use YAHOO.util.Dom.getViewportHeight instead

#### getClientWidth

`static int getClientWidth ( )`
Gets the client width

Returns: `int`
  client width in px

Deprecated use YAHOO.util.Dom.getViewportWidth instead

#### getCss

`static Object getCss ( id )`
Returns the style property for the DOM element (i.e., document.getElById(id).style)

Parameters:
  `id <String>` the id of the elment to get

Returns: `Object`
  The style property of the element

Deprecated use YAHOO.util.Dom instead

#### getDDById

`static DragDrop getDDById ( id )`
Returns the DragDrop instance for a given id

Parameters:
  `id <String>` the id of the DragDrop object

Returns: `DragDrop`
  the drag drop object, null if it is not found

#### getElement

`static Object getElement ( id )`
Returns the actual DOM element

Parameters:
  `id <String>` the id of the elment to get

Returns: `Object`
  The element

Deprecated use YAHOO.util.Dom.get instead

#### getElWrapper

`private static YAHOO.util.DDM.ElementWrapper getElWrapper ( id )`
Get the wrapper for the DOM element specified

Parameters:
  `id <String>` the id of the element to get

Returns: `YAHOO.util.DDM.ElementWrapper`
  the wrapped element

Deprecated This wrapper isn't that useful

#### getLocation

`static YAHOO.util.Region getLocation ( oDD )`
Returns a Region object containing the drag and drop element's position and size, including the padding configured for it

Parameters:
  `oDD <DragDrop>` the drag and drop object to get the location for

Returns: `YAHOO.util.Region`
  a Region object representing the total area the element occupies, including any padding the instance is configured for.

#### getPosX

`static int getPosX ( el )`
Returns the X position of an html element

Parameters:
  `el <object>` the element for which to get the position

Returns: `int`
  the X coordinate

Deprecated use YAHOO.util.Dom.getX instead

#### getPosY

`static int getPosY ( el )`
Returns the Y position of an html element

Parameters:
  `el <object>` the element for which to get the position

Returns: `int`
  the Y coordinate

Deprecated use YAHOO.util.Dom.getY instead

#### getRelated

`static DragDrop[] getRelated ( p_oDD , bTargetsOnly )`
Returns the drag and drop instances that are in all groups the passed in instance belongs to.

Parameters:
  `p_oDD <DragDrop>` the obj to get related data for
  `bTargetsOnly <boolean>` if true, only return targetable objs

Returns: `DragDrop[]`
  the related instances

#### getScroll

`private static void getScroll ( )`
Returns the current scroll position

Returns: `void`

#### getScrollLeft

`static int getScrollLeft ( )`
Gets the scrollLeft

Returns: `int`
  the document's scrollTop

#### getScrollTop

`static int getScrollTop ( )`
Gets the scrollTop

Returns: `int`
  the document's scrollTop

#### getStyle

`static string getStyle ( el , styleProp )`
Returns the specified element style property

Parameters:
  `el <HTMLElement>` the element
  `styleProp <string>` the style property

Returns: `string`
  The value of the style property

Deprecated use YAHOO.util.Dom.getStyle

#### handleMouseDown

`private static void handleMouseDown ( e , oDD )`
Fired after a registered DragDrop object gets the mousedown event. Sets up the events required to track the object being dragged

Parameters:
  `e <Event>` the event
  `oDD <object>` the DragDrop object being dragged

Returns: `void`

#### handleMouseMove

`private static void handleMouseMove ( e )`
Internal function to handle the mousemove event. Will be invoked from the context of the html element.

Parameters:
  `e <Event>` the event

Returns: `void`

#### handleMouseUp

`private static void handleMouseUp ( e )`
Internal function to handle the mouseup event. Will be invoked from the context of the document.

Parameters:
  `e <Event>` the event

Returns: `void`

#### handleWasClicked

`static void handleWasClicked ( node )`
Recursively searches the immediate parent and all child nodes for the handle element in order to determine wheter or not it was clicked.

Parameters:
  `node <object>` the html element to inspect

Returns: `void`

#### init

`private static void init ( )`
Called the first time an element is registered.

Returns: `void`

#### isDragDrop

`static boolean isDragDrop ( id )`
Utility function to determine if a given element has been registered as a drag drop item.

Parameters:
  `id <String>` the element id to check

Returns: `boolean`
  true if this element is a DragDrop item, false otherwise

#### isHandle

`static boolean isHandle ( id )`
Utility function to determine if a given element has been registered as a drag drop handle for the given Drag Drop object.

Parameters:
  `id <String>` the element id to check

Returns: `boolean`
  true if this element is a DragDrop handle, false otherwise

#### isLegalTarget

`static boolean isLegalTarget ( the )`
Returns true if the specified dd target is a legal target for the specifice drag obj

Parameters:
  `the <DragDrop>` drag obj
  `the <DragDrop>` target

Returns: `boolean`
  true if the target is a legal target for the dd obj

#### isLocked

`static boolean isLocked ( )`
Is drag and drop locked?

Returns: `boolean`
  True if drag and drop is locked, false otherwise.

#### isOverTarget

`private static boolean isOverTarget ( pt , oTarget , intersect , pre-cached )`
Checks the cursor location to see if it over the target

Parameters:
  `pt <YAHOO.util.Point>` The point to evaluate
  `oTarget <DragDrop>` the DragDrop object we are inspecting
  `intersect <boolean>` true if we are in intersect mode
  `pre-cached <YAHOO.util.Region>` location of the dragged element

Returns: `boolean`
  true if the mouse is over the target

#### isTypeOfDD

`static boolean isTypeOfDD ( the )`
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.

Parameters:
  `the <Object>` object to evaluate

Returns: `boolean`
  true if typeof oDD = DragDrop

#### lock

`static void lock ( )`
Lock all drag and drop functionality

Returns: `void`

#### moveToEl

`static void moveToEl ( moveEl , targetEl )`
Sets the x/y position of an element to the location of the target element.

Parameters:
  `moveEl <HTMLElement>` The element to move
  `targetEl <HTMLElement>` The position reference element

Returns: `void`

#### numericSort

`static void numericSort ( )`
Numeric array sort function

Returns: `void`

#### refreshCache

`static void refreshCache ( groups )`
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: `YAHOO.util.DragDropMgr.refreshCache(ddinstance.groups);` Alternatively: `YAHOO.util.DragDropMgr.refreshCache({group1:true, group2:true});`

Parameters:
  `groups <Object>` an associative array of groups to refresh

Returns: `void`

#### regDragDrop

`static void regDragDrop ( oDD , sGroup )`
Each DragDrop instance must be registered with the DragDropMgr. This is executed in DragDrop.init()

Parameters:
  `oDD <DragDrop>` the DragDrop object to register
  `sGroup <String>` the name of the group this element belongs to

Returns: `void`

#### regHandle

`static void regHandle ( sDDId , sHandleId )`
Each DragDrop handle element must be registered. This is done automatically when executing DragDrop.setHandleElId()

Parameters:
  `sDDId <String>` the DragDrop id this element is a handle for
  `sHandleId <String>` the id of the element that is the drag handle

Returns: `void`

#### removeDDFromGroup

`private static void removeDDFromGroup ( )`
Removes the supplied dd instance from the supplied group. Executed by DragDrop.removeFromGroup, so don't call this function directly.

Returns: `void`

#### startDrag

`static void startDrag ( x , y )`
Fired when either the drag pixel threshold or the mousedown hold time threshold has been met.

Parameters:
  `x <int>` the X position of the original mousedown
  `y <int>` the Y position of the original mousedown

Returns: `void`

#### stopDrag

`static void stopDrag ( e , silent )`
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.)

Parameters:
  `e <Event>` the mouseup event, another event (or a fake event) with pageX and pageY defined, or nothing if the silent parameter is true
  `silent <boolean>` skips the enddrag and mouseup events if true

Returns: `void`

#### stopEvent

`static void stopEvent ( e )`
Utility to stop event propagation and event default, if these features are turned on.

Parameters:
  `e <Event>` the event as returned by this.getEvent()

Returns: `void`

#### swapNode

`static void swapNode ( n1 , n2 )`
Swap two nodes. In IE, we use the native method, for others we emulate the IE behavior

Parameters:
  `n1 <object>` the first node to swap
  `n2 <object>` the other node to swap

Returns: `void`

#### unlock

`static void unlock ( )`
Unlock all drag and drop functionality

Returns: `void`

#### unregAll

`private static void unregAll ( )`
Cleans up the drag and drop events and objects.

Returns: `void`

#### verifyEl

`static boolean verifyEl ( el )`
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

Parameters:
  `el <HTMLElement>` the element to check

Returns: `boolean`
  true if the element looks usable

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