IVsHierarchyDropDataTarget.DragEnter Method

Called as soon as the mouse drags an item over a new hierarchy or hierarchy window.

Namespace:  Microsoft.VisualStudio.Shell.Interop
Assembly:  Microsoft.VisualStudio.Shell.Interop (in Microsoft.VisualStudio.Shell.Interop.dll)

Syntax

'宣言
Function DragEnter ( _
    pDataObject As IDataObject, _
    grfKeyState As UInteger, _
    itemid As UInteger, _
    <OutAttribute> ByRef pdwEffect As UInteger _
) As Integer
'使用
Dim instance As IVsHierarchyDropDataTarget
Dim pDataObject As IDataObject
Dim grfKeyState As UInteger
Dim itemid As UInteger
Dim pdwEffect As UInteger
Dim returnValue As Integer

returnValue = instance.DragEnter(pDataObject, _
    grfKeyState, itemid, pdwEffect)

int DragEnter(
    IDataObject pDataObject,
    uint grfKeyState,
    uint itemid,
    out uint pdwEffect
)

int DragEnter(
    [InAttribute] IDataObject^ pDataObject, 
    [InAttribute] unsigned int grfKeyState, 
    [InAttribute] unsigned int itemid, 
    [InAttribute] [OutAttribute] unsigned int% pdwEffect
)

function DragEnter(
    pDataObject : IDataObject, 
    grfKeyState : uint, 
    itemid : uint, 
    pdwEffect : uint
) : int

Parameters

• pDataObject
  Type: Microsoft.VisualStudio.OLE.Interop.IDataObject

  [in] Pointer to the IDataObject interface on the item being dragged. This data object contains the data being transferred in the drag-and-drop operation. If the drop occurs, then this data object (item) is incorporated into the hierarchy window.

• grfKeyState
  Type: System.UInt32

  [in] Current state of the keyboard and the mouse modifier keys. Valid values are shown in the following table. These values can be combined using a bitwise OR operator.

  Hex	Value	Description
  0x0001	MK_LBUTTON	Left mouse button is clicked.
  0x0002	MK_RBUTTON	Right mouse button is clicked.
  0x0004	MK_SHIFT	SHIFT key is pressed.
  0x0008	MK_CONTROL	CONTROL key is pressed.
  0x0010	MK_MBUTTON	Middle mouse button is clicked.
  0x0020	MK_ALT	ALT key is pressed.

• itemid
  Type: System.UInt32

  [in] Item identifier of the item currently being dragged. For a list of itemid values, see VSITEMID.

• pdwEffect
  Type: System.UInt32%

  [in, out] On entry, pointer to the value of the pdwEffect parameter of the IVsHierarchy object, identifying all effects that the hierarchy supports. On return, must contain one of the effect flags that indicate the result of the drop operation. For more information, see IVsHierarchyDropDataSource2.

Return Value

Type: System.Int32

If the method succeeds, it returns S_OK. If it fails, it returns an error code.

Remarks

COM Signature

From vsshell.idl:

HRESULT IVsHierarchyDropDataTarget::DragEnter(
   [in]IDataObject * pDataObject,
   [in]DWORD grfKeyState,
   [in]VSITEMID itemid,
   [in, out]DWORD * pdwEffect
);

The DragEnter method is called when an item first enters the hierarchy window or when the item is dragged over a new hierarchy. After calling the DragEnter method, the hierarchy calls the DragOver method until the item leaves the new hierarchy or hierarchy window, at which point it calls the DragLeave or Drop method.

The DragEnter method also passes in the state of the keyboard keys and mouse buttons (whether one or more is being pressed).

Drop effects are included in the pdwEffect parameter and describe the action associated with a drop operation. The following table shows possible pdwEffect values and their descriptions:

The values of the pwdEffects parameter are taken from the DragDropEffects enumeration.

Permissions

• Full trust for the immediate caller. This member cannot be used by partially trusted code. For more information, see Using Libraries from Partially Trusted Code.

See Also

Reference

IVsHierarchyDropDataTarget Interface

IVsHierarchyDropDataTarget Members

Microsoft.VisualStudio.Shell.Interop Namespace