drag and drop - C# DragEnter event of the Winforms DragDrop -

Why do we really have to handle the drag destination event dragent?

What is the effect of this destination?

at source

  Public Partial Classroom Toolbox: System.Windows.Forms.Form {Public ToolboxForm () {InitializeComponent (); } Private Zero lbl_MouseDown (Object Sender, System.Windows.Forms.MouseEventArgs e) {label lbl = (Label) Sender; Lbl.DoDragDrop (lbl.Image, DragDropEffects.Link); }}  

at destination:

  public partial square DrawingArea: form {public drawingia () {InitializeComponent (); } Private Zero DrawingArea_Load (Object Sender, System.EventArgs e) {ToolboxForm toolBoxForm = new ToolboxForm (); This.AddOwnedForm (toolBoxForm); ToolBoxForm.Show (); PictureBox1.AllowDrop = True; } Private Zero picDrawingArea_DragEnter (Object Sender, System.Windows.Forms.DragEventArgs e) {if (e.Data.GetDataPresent (DataFormats.Bitmap)) {e.ffect = DragDropEffects.Copy; } And {e. Effect = drag effect; }} Private Zero picDrawingArea_DragDrop (Object Sender, System.Windows.Forms.DragEventArgs e) {Graphics G = pictureBox1.CreateGraphics (); G.DrawImage (image) E. Data. GetData (DataFormats.Bitmap), new point (E.X - this. Lift-12, E.I. - Top-30)); }}  

When I am commenting on the code:

  if (e.Data.GetDataPresent (DataFormats.Bitmap)) {e.ffect = DragDropEffects .Copy; } And {e. Effect = drag effect; }  

The image is not being omitted.

From

From:

Members
Name < Code> details
any The drop target does not accept data.
Copy Data is copied from the drag source to the drop target. < Data from drag source is moved to the drop target.
Link is linked to the data drop target from the drag source .
> You can scroll to ; The target can be scrolled while dragging to detect drop down, which is not currently visible in the target.
All odi> copy, Combination of move and scroll effects

So if you want to accept the drop, you have to set it apart from any .

However, the next quote assures me that it was used only for feedback:

You can display various mouse pointers for drag-and-drop operations You can use DragDropEffects for. For example, you can display a plus sign for a copy drag-and-drop operation, a Move drag-and-drop operation, or a red circle An arrow for any with a line through it for drag-and-drop operation.