Application Getting Focus
lazarus / 31-LCL

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sfeinst · 2011-07-12 00:01

I need to determine when my application gets the focus from another
application.  In general, what I am trying to do, is determine if I
need to enable a Paste menu.  Since a user could go into another app
(say text editor) and copy text to the clipboard and then return to my
app, how do I do this?  I tried OnActivate of the form, but that seems
to only get fired at the beginning of the app when loading.  I tried
OnEnter of a tmemo, but if the memo had focus when the user clicked to
another app, this even does not fire, since it still has focus when
returning to the app.

Any suggestions?

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felipemdc · 2011-07-19 07:41

TForm.OnActivate is only for focus change between forms of the same
program.

For focus change between applications the event Application.OnActivate
is called and I just tested that it works fine in linux-qt

Code: [Select]procedure TForm1.FormActivate(Sender: TObject); // Not
connected to TForm.OnActivate
begin
  Caption := 'OnActive ' + IntToStr(Counter);
  Inc(Counter);
end;

procedure TForm1.FormCreate(Sender: TObject); // Connected to
TForm.OnCreate
begin
  Application.OnActivate:=@FormActivate;
end;

See also:

http://docs.embarcadero.com/products/rad_studio/delphiAndcpp2009/HelpU
pdate2/EN/html/delphivclwin32/Forms_TCustomForm_OnActivate.html

I documented this also in our docs, but it will probably take a lot of
time before the online docs are updated. Link for future use:

http://lazarus-
ccr.sourceforge.net/docs/lcl/forms/tcustomform.onactivate.html

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sfeinst · 2011-07-19 19:30

Thanks.  That got me most of the way there.  It definitely fires which
is what I wanted, but for some reason, the control with focus is not
cosidered to have focus when that event fires, so manually keeping
track of control with focus (because the focused control affects what
is enabled/disabled).

Thanks.

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Mike.Cornflake · 2011-07-24 17:59

You could try a different tack - put the menu enabling code in the
OnPopup of your menu...   That way it'll work even if the user puts
something in the clipboard from elsewhere in your application.

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avra · 2011-08-04 08:39

Take a look at the solution here:
http://www.lazarus.freepascal.org/index.php/topic,13958.0.html

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Elmug · 2011-08-05 10:57

Just a simpleton view here: If the user leaves your application, what
is there to say that he has copied elsewhere and wishes to come back
to your application to paste it? Perhaps the user just went to do
whatever, not necessarily copy something?

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Avishai · 2011-08-05 11:14

Would TForm.ActiveControl.Name give you what you need?

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sfeinst · 2011-08-05 17:50

Quote from: Elmug on August 05, 2011, 12:57:49 pmJust a simpleton view
here: If the user leaves your application, what is there to say that
he has copied elsewhere and wishes to come back to your application to
paste it? Perhaps the user just went to do whatever, not necessarily
copy something?
That is true.  That is why on return to my app I check the clipboard
to see if there is anything that can be pasted.  If so, I enable the
correct options.

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sfeinst · 2011-08-05 17:55

Quote from: Avishai on August 05, 2011, 01:14:33 pmWould
TForm.ActiveControl.Name give you what you need?
Thank you.  That is what I was looking for.  I had been using
Control.Focused.  Form.ActiveControl makes more sense.

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Avishai · 2011-08-05 18:02

This might be more usefull

case Form1.ActiveControl.TabOrder of
  0: begin ...end;
  1: begin ...end;
  ...
end;