Last Position of Focus

Posted on 1998-12-13
Last Modified: 2010-04-04
Is it possible in Delphi 4, to see which Element (Edit, Button, etc.) had the Focus before the user changed it, by clicking or tab-mode to another element. Once, the old Focus is now, i want to set it back (probly using .SetFocus) on the OnExit-Event of the new (current) focused element.
Question by:omsec
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Author Comment

ID: 1350834
ops, some typos
tab-mode = tab-move
now = known

Expert Comment

ID: 1350835
Of course you can, suppose the new(current) focued control is edit2, then in Edit2's OnExit event, you can write:
See the help for SelectNext method and you get all.

However,this method works only for changing focus by TAB-move, not for Mouse click. If you gonna want one method for mouse click, I think you need a variable to record the old control on each focus change.
LVL 20

Expert Comment

ID: 1350836
You could hook all WM_KILLFOCUS messages by writing an Application.OnMessage handler. Please look in the documentation about Application.OnMessage. The WM_KILLFOCUS tells you the handle of the window control, that has lost the focus.

Regards, Madshi.
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Expert Comment

ID: 1350837
I typing this from memory so...
In the onexit event of your components get the active control and store it in a tobject,
so whenever you want you can switch back to the latest selected component.
use the form's activecontrol to get the current selected component.
If it's still necessary, i'l bring you back some code tommorow.

Accepted Solution

rickpet earned 20 total points
ID: 1350838
The Screen object(TScreen) has a property called ActiveControl
it also has an event called OnActiveControlChange

Just create an object of type TWincontol

declared in the Form's Interface:

FLastControl : TWinControl;
procedure OnScreenControlChange(Sender: TObject);

On the forms create...add:
Screen.OnActiveControlChange := OnScreenControlChange;

procedure TForm1.OnScreenControlChange(Sender: TObject);
  FLastControl := Screen.ActiveControl;

on the forms destroy add:

Screen.OnActiveControlChange := nil;


Expert Comment

ID: 1350839
this is how I'm doing it too.

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