/// <summary>
/// Raises the DragEnter event.
/// </summary>
/// <param name="e">A DragEventArgs that contains the event data.</param>
protected override void OnDragEnter(DragEventArgs e)
{
// Call the base class's method so that registered delegates receive the event.
base.OnDragEnter(e);
// Find the drag-and-drop lightweight control at the mouse position.
LightweightControl lightweightControl = GetDragDropLightweightControlAtClientPoint(PointToClient(new Point(e.X, e.Y)));
// If there is a drag-and-drop lightweight control at the mouse position, the event
// is for it. Otherwise, it's for this control.
if (lightweightControl != null)
{
// Set the drag-and-drop lightweight control and raise its DragEnter event.
dragDropLightweightControl = lightweightControl;
e.Effect = DragDropEffects.None;
dragDropLightweightControl.RaiseDragInside(e);
}
}
/// <summary>
/// Update the drag-and-drop lightweight control. Detects whether the drag-and-drop
/// lightweight control has changed, and raises the appropriate events, if it has.
/// </summary>
/// <param name="e">A MouseEventArgs containing the event data.</param>
private void UpdateDragDropLightweightControl(DragEventArgs e)
{
// Find the drag-and-drop lightweight control at the mouse position.
LightweightControl lightweightControl = GetDragDropLightweightControlAtClientPoint(PointToClient(new Point(e.X, e.Y)));
// If the drag-and-drop lightweight control is changing, make the change.
if (lightweightControl != dragDropLightweightControl)
{
// If we have a drag-and-drop lightweight control, raise its OnDragLeave event.
// Otherwise, call the base class's method to raise the OnDragLeave event on
// this control.
if (dragDropLightweightControl != null)
dragDropLightweightControl.RaiseDragOutside(EventArgs.Empty);
else
OnDragOutside(EventArgs.Empty);
// Set the drag-and-drop lightweight control.
dragDropLightweightControl = lightweightControl;
e.Effect = DragDropEffects.None;
// If we have a drag-and-drop lightweight control, raise its DragEnter event.
// Otherwise, call the base class's method to raise the DragEnter event on this
// control.
if (dragDropLightweightControl != null)
dragDropLightweightControl.RaiseDragInside(e);
else
OnDragInside(e);
}
}