DragEventArgs Class


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Provides data for the DragDrop, DragEnter, or DragOver event.

Namespace:   System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)

public class DragEventArgs : EventArgs

System_CAPS_pubmethodDragEventArgs(IDataObject, Int32, Int32, Int32, DragDropEffects, DragDropEffects)

Initializes a new instance of the DragEventArgs class.


Gets which drag-and-drop operations are allowed by the originator (or source) of the drag event.


Gets the IDataObject that contains the data associated with this event.


Gets or sets the target drop effect in a drag-and-drop operation.


Gets the current state of the SHIFT, CTRL, and ALT keys, as well as the state of the mouse buttons.


Gets the x-coordinate of the mouse pointer, in screen coordinates.


Gets the y-coordinate of the mouse pointer, in screen coordinates.


Determines whether the specified object is equal to the current object.(Inherited from Object.)


Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)


Serves as the default hash function. (Inherited from Object.)


Gets the Type of the current instance.(Inherited from Object.)


Creates a shallow copy of the current Object.(Inherited from Object.)


Returns a string that represents the current object.(Inherited from Object.)

The DragDrop event occurs when the user completes a drag-and-drop operation by dragging an object over the control and then dropping it onto the control by releasing the mouse button. The DragEnter event occurs when the user moves the mouse pointer onto the control while dragging an object with the mouse. The DragOver event occurs when the user moves the mouse pointer over the control while dragging an object with the mouse.

A DragEventArgs object specifies any data associated with this event; the current state of the SHIFT, CTRL, and ALT keys; the location of the mouse pointer; and the drag-and-drop effects allowed by the source and target of the drag event.

For information about the event model, see Handling and Raising Events.

The following example demonstrates a drag-and-drop operation between two ListBox controls. The example calls the DoDragDrop method when the drag action starts. The drag action starts if the mouse has moved more than SystemInformation.DragSize from the mouse location during the MouseDown event. The IndexFromPoint method is used to determine the index of the item to drag during the MouseDown event.

The example also demonstrates using custom cursors for the drag-and-drop operation. The example assumes that two cursor files, 3dwarro.cur and 3dwno.cur, exist in the application directory, for the custom drag and no-drop cursors, respectively. The custom cursors will be used if the UseCustomCursorsCheckCheckBox is checked. The custom cursors are set in the GiveFeedback event handler.

The keyboard state is evaluated in the DragOver event handler for the right ListBox, to determine what the drag operation will be based upon state of the SHIFT, CTRL, ALT, or CTRL+ALT keys. The location in the ListBox where the drop would occur is also determined during the DragOver event. If the data to drop is not a String, then the DragEventArgs.Effect is set to DragDropEffects.None. Finally, the status of the drop is displayed in the DropLocationLabelLabel.

The data to drop for the right ListBox is determined in the DragDrop event handler and the String value is added at the appropriate place in the ListBox. If the drag operation moves outside the bounds of the form, then the drag-and-drop operation is canceled in the QueryContinueDrag event handler.

This code excerpt demonstrates using the DragEventArgs class. See the DoDragDrop method for the complete code example.

private void ListDragTarget_DragOver(object sender, System.Windows.Forms.DragEventArgs e) 

    // Determine whether string data exists in the drop data. If not, then
    // the drop effect reflects that the drop cannot occur.
    if (!e.Data.GetDataPresent(typeof(System.String))) {

        e.Effect = DragDropEffects.None;
        DropLocationLabel.Text = "None - no string data.";

    // Set the effect based upon the KeyState.
    if ((e.KeyState & (8+32)) == (8+32) && 
        (e.AllowedEffect & DragDropEffects.Link) == DragDropEffects.Link) {
        // KeyState 8 + 32 = CTL + ALT

        // Link drag-and-drop effect.
        e.Effect = DragDropEffects.Link;

    } else if ((e.KeyState & 32) == 32 && 
        (e.AllowedEffect & DragDropEffects.Link) == DragDropEffects.Link) {

        // ALT KeyState for link.
        e.Effect = DragDropEffects.Link;

    } else if ((e.KeyState & 4) == 4 && 
        (e.AllowedEffect & DragDropEffects.Move) == DragDropEffects.Move) {

        // SHIFT KeyState for move.
        e.Effect = DragDropEffects.Move;

    } else if ((e.KeyState & 8) == 8 && 
        (e.AllowedEffect & DragDropEffects.Copy) == DragDropEffects.Copy) {

        // CTL KeyState for copy.
        e.Effect = DragDropEffects.Copy;

    } else if ((e.AllowedEffect & DragDropEffects.Move) == DragDropEffects.Move)  {

        // By default, the drop action should be move, if allowed.
        e.Effect = DragDropEffects.Move;

    } else
        e.Effect = DragDropEffects.None;

    // Get the index of the item the mouse is below. 

    // The mouse locations are relative to the screen, so they must be 
    // converted to client coordinates.

    indexOfItemUnderMouseToDrop = 
        ListDragTarget.IndexFromPoint(ListDragTarget.PointToClient(new Point(e.X, e.Y)));

    // Updates the label text.
    if (indexOfItemUnderMouseToDrop != ListBox.NoMatches){

        DropLocationLabel.Text = "Drops before item #" + (indexOfItemUnderMouseToDrop + 1);
    } else
        DropLocationLabel.Text = "Drops at the end.";


The following example illustrates how DragEventArgs are passed between the source and target of a drag-and-drop operation. In this example, a ListBox control is the source of the data, and the RichTextBox control is the target. The example assumes that the ListBox control has been populated with a list of valid filenames. When the user drags one of the displayed filenames from the ListBox control onto the RichTextBox control, the file referenced in the filename is opened.

The operation is initiated in the ListBox control's MouseDown event. In the DragEnter event handler, the example uses the GetDataPresent method to verify that the data is in a format that the RichTextBox control can display and then sets the DragDropEffects property to specify that data should be copied from the source control to the target control. Finally, the RichTextBox control's DragDrop event handler uses the GetData method to retrieve the filename to open.

private void Form1_Load(object sender, EventArgs e) 
   // Sets the AllowDrop property so that data can be dragged onto the control.
   richTextBox1.AllowDrop = true;

   // Add code here to populate the ListBox1 with paths to text files.


private void listBox1_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e)
   // Determines which item was selected.
   ListBox lb =( (ListBox)sender);
   Point pt = new Point(e.X,e.Y);
   int index = lb.IndexFromPoint(pt);

   // Starts a drag-and-drop operation with that item.
      lb.DoDragDrop(lb.Items[index].ToString(), DragDropEffects.Link);

private void richTextBox1_DragEnter(object sender, DragEventArgs e) 
   // If the data is text, copy the data to the RichTextBox control.
      e.Effect = DragDropEffects.Copy;

private void richTextBox1_DragDrop(object sender, DragEventArgs e) 
   // Loads the file into the control. 
   richTextBox1.LoadFile((String)e.Data.GetData("Text"), System.Windows.Forms.RichTextBoxStreamType.RichText);

.NET Framework
Available since 1.1

Any public static ( Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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