Indicates whether or not a drop can be accepted and the drop's effect if
| IDataObject * pDataObject,
||//IDataObject interface for the source data
| DWORD grfKeyState,
||//Current state of keyboard modifier keys
| POINTL pt,
||//Current cursor coordinates
| DWORD * pdwEffect
||//Effect of the drag-and-drop operation
[in] Points to the data object being transferred in the drag-and-drop
operation. The data is represented in the IDataObject
interface. If the drop occurs, this data object will be incorporated into the
[in] Identifies the current state of the keyboard modifier keys on the
keyboard. Valid values can be a combination of any of the flags MK_CONTROL, MK_SHIFT,
MK_ALT, MK_BUTTON, MK_LBUTTON, MK_MBUTTON, and MK_RBUTTON.
[in] Points to the current cursor coordinates in the coordinate space of the
drop target window.
[in, out] Specifies the current effect flag. Valid values are from the DROPEFFECT
The function completed its task successfully.
Out of memory.
One or more arguments are invalid.
An unexpected error occurred.
function calls this method the first time the user drags the mouse into the
registered window of a drop target.
In the IDropTarget::DragEnter
method, you must determine the effect of dropping the data on the target by
examining the formats and medium specified for the data object along with the
state of the modifier keys. The following modifier keys affect the result of the
|CTRL + SHIFT
|No keys or SHIFT
You communicate the effect of the drop back to the source through DoDragDrop
in the pdwEffect
parameter. The DoDragDrop
function then calls IDropSource::GiveFeedback
so that the source application can display the appropriate visual feedback to
On entry to IDropTarget::DragEnter
, the pdwEffect
parameter is set to the effects given to the DoDragDrop
function. The IDropTarget::DragEnter
method must choose one of these effects or disable the drop.
Upon return, pdwEffect
is set to either DROPEFFECT_COPY to copy the dragged data to the target,
DROPEFFECT_LINK to create a link to the source data, or DROPEFFECT_MOVE to allow
the dragged data to be permanently moved from the source application to the
You may also wish to provide appropriate visual feedback in the target window.
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