Event XbpCrt():dragEnter Foundation

Item has been dragged over a drop zone.

:dragEnter := {| aState, oDragData, self | ... } --> nAction
:dragEnter( aState, oDragData ) --> nAction
xbeP_DragEnter (1048650)
<aState> := { nKeyState, aPos }
<aState> contains information about keys pressed while the item is being dragged, as well as about the mouse pointer position. nKeyState is a numeric value with the keys being held. It is a combination of the XBP_MK_xxx defines from XBP.CH. aPos is a two-dimensional array with the current x and y position of the mouse pointer.

The units used for reporting the mouse pointer position depends on the value assigned to :mouseMode. If XBPCRT_MOUSEMODE_VIO is assigned to this instance variable, the array contains a position in row/column format. Otherwise, the position is specified in pixel.

<oDragData> is an object encapsulating the actual data of the item being dragged. It is an instance of the DragDataObject() class. The application can use the object's methods and member variables to examine the item's data format.

Both the code block and the method must return a numeric value represented by one of the XBP_DROPMODE_xxx constants defined in XBP.CH. The return value indicates whether the application supports dropping the item or items being dragged. If both a method and a code block have been defined, the value returned by the code block takes precedence.


The xbeP_DragEnter event is generated if an item is dragged by the user over an XbpCrt object. If xbeP_DragEnter is received by an Xbase++ application, it must indicate whether it is prepared to accept the item or items being dragged. This is done by returning one of the following constants defined in XBP.CH.

Return values defined for xbeP_DragEnter
Constant Description
XBP_DROPMODE_NONE Application cannot handle the item(s) being dragged
XBP_DROPMODE_COPY *) Drop results in a copy of the item being dragged
XBP_DROPMODE_MOVE Data provider should remove its copy of the item after the drop
XBP_DROPMODE_LINK Data provider should create a link to the original item
  1. Default value

If the application returns a value other than XBP_DROPMODE_NONE, the system displays a type of mouse pointer that indicates to the user that the item can be dropped at the current location. If XBP_DROPMODE_NONE is returned, the mouse pointer is changed to indicate that dropping the item would have no effect.

The xbeP_DragEnter event is sent synchronously via the :handleEvent() method of an XbpCrt object. This means that xbeP_DragEnter is not by the AppEvent() function. As it is generated while the user manipulates an item, we strongly discourage to perform lengthy operations while processing the event.

An example that illustrates how to accept items being dragged can be found under :dropZone.

The xbeP_DragEnter event is generated only if the value .T. (true) is assigned to the object's :dropZone instance variable. Also, mouse events must be enabled using SetMouse(.T.).


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