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keyboard events in controls

Posted on 1998-12-29
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Last Modified: 2010-04-04
I have the simplest control:

TMycontrol = class( TCustomControl )
public
   procedure Paint; override;
end;

I place two such controls on the panel and look how they receive keyboard messages (I use WinSpy). What do I see:
When I click the button one control receive WM_KEYUP and other receive WM_KEYDOWN, on the next click first one receive WM_KEYDOWN and second one WM_KEYUP.
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Question by:eugenem
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4 Comments
 
LVL 3

Author Comment

by:eugenem
ID: 1353531
One more trouble:
When I use only one control, I don't receive WM_KEYDOWN event after click of conrol keys (arrows, etc.) but receive it on any other keys (alphanumeric, etc.) that produce WM_CHAR event.
Spy++ shows that control's window always receive WM_KEYDOWN.
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LVL 20

Expert Comment

by:Madshi
ID: 1353532
The keyboard events are sent to the control that has the focus. So when you press arrow keys, probably the focus is changing from one control to the other between the WM_KEYDOWN and the WM_KEYUP message. That's probably why one control gets the WM_KEYUP and the other control gets the WM_KEYDOWN message.

Please look at which control has the focus.

Regards, Madshi.
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LVL 3

Author Comment

by:eugenem
ID: 1353533
That's right. So how can I keep focus on my control?
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LVL 20

Accepted Solution

by:
Madshi earned 400 total points
ID: 1353534
Implement a message handler for the WM_GetDlgCode message. Here is a part of the code of TMemo:
  ...
  private
    procedure WMGetDlgCode(var Message: TWMGetDlgCode); message WM_GETDLGCODE;
  ...

procedure TCustomMemo.WMGetDlgCode(var Message: TWMGetDlgCode);
begin
  inherited;
  if FWantTabs then Message.Result := Message.Result or DLGC_WANTTAB
  else Message.Result := Message.Result and not DLGC_WANTTAB;
  if not FWantReturns then
    Message.Result := Message.Result and not DLGC_WANTALLKEYS;
end;

Regards, Madshi.
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