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TCustomControl DragOver Event

Posted on 2007-11-28
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Last Modified: 2013-11-23
I am trying to teach myself drag'n'drop in Delphi and have created a component (TMyControl) which is a descendant of TCustomControl and have published the OnDragOver event:

TMyControl = class(TCustomControl)
:
  private
    { Private declarations }
    FOnDragOver: TDragOverEvent;
:
  published
    { Published declarations }
    property OnDragOver: TDragOverEvent read FOnDragOver write FOnDragOver;
:
end;

I have written code for MyControl1DragOver:

procedure TForm1.MyControl1DragOver(Sender, Source: TObject; X, Y: Integer; State: TDragState; var Accept: Boolean);
begin
:
  // some code in here just to prove it works
:
end;

But, this event does not fire when I drag something over MyControl1.

What more should I do to get MyControl1 to fire its DragOver event?
0
Comment
Question by:plumothy
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3 Comments
 
LVL 26

Accepted Solution

by:
EddieShipman earned 2000 total points
ID: 20368895
Put a breakpoint in TWinControl.CMDrag and see if it breaks there.
0
 

Author Comment

by:plumothy
ID: 20370003
Yes, it breaks in TWinControl.CMDrag when dragging over the control.

Thanks for that. I am quickly learning a lot about drag and drop!

I have followed the code execution in the debugger and can see where I have gone wrong.

I had a second control contained in MyControl1and it was this second control which fires its DragOver event - not MyControl1.

Once again, thanks for pointing me in the right direction.
0
 

Author Closing Comment

by:plumothy
ID: 31411407
The solution pointed me in the right direction so I quickly found out what I had done wrong!
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