How to bring a Form in front over all programs and give it the focus?

[Hartmut]

My program mostly runs in the background. But if some event is detected, it shall:
a) display a Form with a message and
b) display this Form over all other windows of all other programs and
c) receive the focus (so that e.g. keystrokes are noticed by my program).

What I have is this:

Code: Pascal  [Select][+][-]

1. if event_detected then
2.    begin
3.    Form1.Show; {calls Form1.BringToFront}
4.    Form1.FormStyle:=fsStayOnTop;
5.    Form1.SetFocus; {does not work}
6.    Form1.Label1.Caption:='This is my message';
7.    end;

This code has 3 disadvantages:
1) If my Form had been hidden by a Button via "Form1.Hide" and then the next message shall be displayed, my Form gets visible, but does not receive the focus.
2) If my Form had been minimized and then the next message shall be displayed, my Form also gets visible, but does not receive the focus.
3) If my Form had been moved manually half behind another window and then the next message shall be displayed, my Form stays half behind the other window (does not come to front).

What I do not need (and not want) is, that after my Form has come in front, that it "stays" in front permanently, even if another window is moved over it.

I use Lazarus 2.0.10 with FPC 3.2.0 on Linux Ubuntu 22.04. Same results with Lazarus 2.2.4 and FPC 3.2.2. How can I solve the 3 disadvantages? Thanks in advance.

EDIT:
Meanwhile I tested my program on Windows and there everything is fine. So the problem is only on Linux.

[Handoko]

Have you tried TForm.BringToFront ?

[KodeZwerg]

This does not work when currently something is in edit mode.

uses LCLType, LCLIntf ...

Code: Pascal  [Select][+][-]

1. procedure MakeFormVisible(const AForm: TForm);
2. var
3.   Rect: TRect;
4.   ScreenWidth, ScreenHeight,
5.   WindowWidth, WindowHeight,
6.   NewX, NewY: Integer;
7. begin
8.   AForm.Position := poDesigned;
9.   if IsIconic(AForm.Handle) then
10.     ShowWindow(AForm.Handle, SW_RESTORE);
11.   GetWindowRect(AForm.Handle, Rect);
12.   WindowWidth := Rect.Right - Rect.Left;
13.   WindowHeight := Rect.Bottom - Rect.Top;
14.   ScreenWidth := Screen.Width;
15.   ScreenHeight := Screen.Height;
16.   NewX := (ScreenWidth - WindowWidth) div 2;
17.   NewY := (ScreenHeight - WindowHeight) div 2;
18.   SetWindowPos(AForm.Handle, HWND_TOP, NewX, NewY, 0, 0, SWP_NOSIZE or SWP_NOZORDER);
19.   SetForegroundWindow(AForm.Handle);
20.   SetFocus(AForm.Handle);
21. end;

[Hartmut]

Have you tried TForm.BringToFront ?

Thank you Handoko. Yes:

If I use "Form1.BringToFront" without other commands before, then I get an error message "[TCustomForm.SetFocus] Form1:TForm1 Can not focus".

If I put a "Form1.Show" before "Form1.BringToFront", then my Form opens each time minimized, after it had been hidden by a Button via "Form1.Hide".

If I put a "Form1.Show" and a "Form1.FormStyle:=fsStayOnTop" before "Form1.BringToFront", then I have the same behaviour as without the "Form1.BringToFront" (see 3 disadvantages above).

Now I will check the suggestion from KodeZwerg...

[Hartmut]

Thank you KodeZwerg for your suggestion. Unfortunately it does not work for me:

If I use your suggestion without other commands, then my Form is *not* displayed at all.

If I use your suggestion after a "Form1.Show", then my Form opens each time minimized, after it had been hidden by a Button via "Form1.Hide".

If I use your suggestion after a "Form1.Show" and a "Form1.FormStyle:=fsStayOnTop", then I have the same behaviour as without your suggestion (see 3 disadvantages above).

Have you seen that I'm on Linux?

[KodeZwerg]

Here is my complete test, on a button press the form gets minimized and as soon the timer is fired, it is:
- visible
- centered
- on top of others
- got focus

Code: Pascal  [Select][+][-]

1. unit Unit1;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   LCLType, LCLIntf,
9.   Classes, SysUtils, Forms, Controls, Graphics, Dialogs, ExtCtrls, StdCtrls;
10.  
11. type
12.  
13.   { TForm1 }
14.  
15.   TForm1 = class(TForm)
16.     Button1: TButton;
17.     Timer1: TTimer;
18.     procedure Button1Click(Sender: TObject);
19.     procedure Timer1Timer(Sender: TObject);
20.   private
21.  
22.   public
23.  
24.   end;
25.  
26. var
27.   Form1: TForm1;
28.  
29. implementation
30.  
31. {$R *.lfm}
32.  
33. { TForm1 }
34.  
35. procedure MakeFormVisible(const AForm: TForm);
36. var
37.   Rect: TRect;
38.   ScreenWidth, ScreenHeight,
39.   WindowWidth, WindowHeight,
40.   NewX, NewY: Integer;
41. begin
42.   AForm.Position := poDesigned;
43.   if IsIconic(AForm.Handle) then
44.     ShowWindow(AForm.Handle, SW_RESTORE);
45.   GetWindowRect(AForm.Handle, Rect);
46.   WindowWidth := Rect.Right - Rect.Left;
47.   WindowHeight := Rect.Bottom - Rect.Top;
48.   ScreenWidth := Screen.Width;
49.   ScreenHeight := Screen.Height;
50.   NewX := (ScreenWidth - WindowWidth) div 2;
51.   NewY := (ScreenHeight - WindowHeight) div 2;
52.   SetWindowPos(AForm.Handle, HWND_TOP, NewX, NewY, 0, 0, SWP_NOSIZE or SWP_NOZORDER);
53.   SetForegroundWindow(AForm.Handle);
54.   SetFocus(AForm.Handle);
55. end;
56.  
57. procedure TForm1.Button1Click(Sender: TObject);
58. begin
59.   Self.WindowState := wsMinimized;
60.   Timer1.Enabled := True;
61. end;
62.  
63. procedure TForm1.Timer1Timer(Sender: TObject);
64. begin
65.   MakeFormVisible(Self);
66.   Timer1.Enabled := False;
67. end;
68.  
69. end.

Have you seen that I'm on Linux?

I did do the crossplatform way I thought.

Build a sample app where I can reproduce
a) what you do
b) how you do
c) why it not work
My sample you have in above source. I did not touched the Form properties at all, just created from scratch by put TTimer and TButton on.

[Hartmut]

Thank you KodeZwerg for your demo and for trying to help me:

Your code works for me, if I press your button and then don't click anything and only wait, until your Form becomes visible again.

Problem 1:
For the next test I increased the Timer to 3 seconds: if I press your button and then click onto another window and then wait, until your Form becomes visible, then your Form does not have the focus. In my application it can last some hours, until the event to display a message occurs. In this time the user will click a lot of other windows.

Problem 2:
In my application my Form is hidden by a Button via command "Form1.Hide", not by minimizing the Form via "Self.WindowState := wsMinimized", as you did. So I changed your code to:

Code: Pascal  [Select][+][-]

1. procedure TForm1.Button1Click(Sender: TObject);
2. begin
3. // Self.WindowState := wsMinimized;
4.   Self.Hide;
5.   Timer1.Interval:=1000;
6.   Timer1.Enabled := True;
7. end;

Now, when I click your button (and don't click anything and only wait), your Form does never appear again.

Problem 3:
To solve problem 2, I modified your code to:

Code: Pascal  [Select][+][-]

1. procedure TForm1.Timer1Timer(Sender: TObject);
2. begin
3.   self.Show;
4.   MakeFormVisible(Self);
5.   Timer1.Enabled := False;
6. end;

Now it works, but only, if I don't click in the waiting time somewhere else. If I click during the waiting time onto another window, then this window will cover (hide) your Form completely or partly, depending on the position of your Form.

Can you reproduce the 3 problems?

[440bx]

I just wanted to mention that, generally speaking, OSs (definitely Windows) don't look kindly at an application that simply wants to steal the focus. 

This is because it's very disconcerting for a user to be working in some window and suddenly have another window steal the input.

In the situation you've described, and presuming I understood correctly what you're trying to do, I would show the window with "stay on top" enabled but nothing else.  _After_ the user clicks on the window, either to move it out of the way or do something else with it, I'd remove the "stay on top" attribute for it to behave like a normal window.

The important thing is this: I would not try to steal the focus from whatever window has it at the time because, it often doesn't work (the OS doesn't like it) and, it is "impolite" towards the user who suddenly sees his/her input sent to a window that popped in the way.

HTH.

[Hartmut]

Hello 440bx, thank you for your thoughts. I do agree, that "stealing" the focus could be a problem to the user. I will reflect my plan. But independent from that I would like to learn, how this could be done, if it is possible with not to high efforts.

[440bx]

Hello 440bx, thank you for your thoughts. I do agree, that "stealing" the focus could be a problem to the user. I will reflect my plan. But independent from that I would like to learn, how this could be done, if it is possible with not to high efforts.

You're welcome.

As far as how it can be done, I've never found a way that was foolproof (mostly hacks) and, only for Windows at that.  Bottom line, I cannot be of much help (if any at all) in this case.

[KodeZwerg]

Thank you KodeZwerg for your demo and for trying to help me:

Your code works for me, if I press your button and then don't click anything and only wait, until your Form becomes visible again.

Problem 1:
For the next test I increased the Timer to 3 seconds: if I press your button and then click onto another window and then wait, until your Form becomes visible, then your Form does not have the focus. In my application it can last some hours, until the event to display a message occurs. In this time the user will click a lot of other windows.

Problem 2:
In my application my Form is hidden by a Button via command "Form1.Hide", not by minimizing the Form via "Self.WindowState := wsMinimized", as you did. So I changed your code to:

Code: Pascal  [Select][+][-]

1. procedure TForm1.Button1Click(Sender: TObject);
2. begin
3. // Self.WindowState := wsMinimized;
4.   Self.Hide;
5.   Timer1.Interval:=1000;
6.   Timer1.Enabled := True;
7. end;

Now, when I click your button (and don't click anything and only wait), your Form does never appear again.

Problem 3:
To solve problem 2, I modified your code to:

Code: Pascal  [Select][+][-]

1. procedure TForm1.Timer1Timer(Sender: TObject);
2. begin
3.   self.Show;
4.   MakeFormVisible(Self);
5.   Timer1.Enabled := False;
6. end;

Now it works, but only, if I don't click in the waiting time somewhere else. If I click during the waiting time onto another window, then this window will cover (hide) your Form completely or partly, depending on the position of your Form.

Can you reproduce the 3 problems?

I only can help with the "show" issue, the rest I does not happen here.

Code: Pascal  [Select][+][-]

1. procedure MakeFormVisible(const AForm: TForm);
2. var
3.   Rect: TRect;
4.   ScreenWidth, ScreenHeight,
5.   WindowWidth, WindowHeight,
6.   NewX, NewY: Integer;
7. begin
8.   // give possibility to readjust position
9.   AForm.Position := poDesigned;
10.   // if its minimized
11.   if IsIconic(AForm.Handle) then
12.     ShowWindow(AForm.Handle, SW_RESTORE);
13.   // if its hidden
14.   if (not AForm.Visible) then
15.     AForm.Show;
16.   // calculate center
17.   GetWindowRect(AForm.Handle, Rect);
18.   WindowWidth := Rect.Right - Rect.Left;
19.   WindowHeight := Rect.Bottom - Rect.Top;
20.   ScreenWidth := Screen.Width;
21.   ScreenHeight := Screen.Height;
22.   NewX := (ScreenWidth - WindowWidth) div 2;
23.   NewY := (ScreenHeight - WindowHeight) div 2;
24.   // put window to calculated center
25.   SetWindowPos(AForm.Handle, HWND_TOP, NewX, NewY, 0, 0, SWP_NOSIZE or SWP_NOZORDER);
26.   // set it to foreground
27.   SetForegroundWindow(AForm.Handle);
28.   // give focus
29.   SetFocus(AForm.Handle);
30. end;

I do absolute agree that when a window pop up over my current work plus stealing focus, I would delete that app.
But of course it depend on what kind of application it is.

[ASerge]

My program mostly runs in the background. But if some event is detected, it shall:
a) display a Form with a message and
b) display this Form over all other windows of all other programs and
c) receive the focus (so that e.g. keystrokes are noticed by my program).

In Windows
ShowWindow + SetForegroundWindow. The form flashes on the taskbar to attract attention. Of course the form should have a button on the taskbar (not dialog). The user himself will switch to the window that attracts attention.
AttachThreadInput (to emulate user input to the window thread) + ShowWindow + SetForegroundWindow. In this case, BringToFront and SetFocus are work. After that, I always want to delete such an application.

[Hartmut]

Thank you KodeZwerg for your improvement and the comments. Now problem #2 is solved, but problems #1 and #3 still exist on my Linux system.


Thank you ASerge for your reply. But I have problems to understand, what you want me to do:

In Windows
ShowWindow + SetForegroundWindow. The form flashes on the taskbar to attract attention. Of course the form should have a button on the taskbar (not dialog). The user himself will switch to the window that attracts attention.

Code: Pascal  [Select][+][-]

1. ShowWindow(Form1.Handle, SW_RESTORE);
2. SetForegroundWindow(Form1.handle);

are part of KodeZwerg's code and they don't work (neither with his complete code nor only this 2 commands solely).

AttachThreadInput (to emulate user input to the window thread) + ShowWindow + SetForegroundWindow. In this case, BringToFront and SetFocus are work. After that, I always want to delete such an application.

Do you want me to use Threads? I never worked with this and I think this effort would be too much for me.


BTW: the only purpose of my application is to inform the user about special events which he explicitly asked to get informed about in a way that generates maximum attention. As I wrote to 440bx:

I do agree, that "stealing" the focus could be a problem to the user. I will reflect my plan. But independent from that I would like to learn, how this could be done, if it is possible with not to high efforts.

[ASerge]

are part of KodeZwerg's code and they don't work (neither with his complete code nor only this 2 commands solely).

What equal Form.BorderStyle?

Do you want me to use Threads? I never worked with this and I think this effort would be too much for me.

No.
In Windows, there is only a single thread connected to the input. It is allowed to do SetFocus for it. You can force the thread of your window (MainThreadID) to be connected to the thread of the active window (possibly someone else's application).

[KodeZwerg]

How about instead of bugging users by bringing up a Form in an unfriendly way, just display a self closing Message?

Code: Pascal  [Select][+][-]

1. unit Unit1;
2.  
3. {$mode Delphi}
4.  
5. interface
6.  
7. uses
8.   Classes, SysUtils, Forms, Controls, Graphics, Dialogs, StdCtrls, ExtCtrls;
9.  
10. type
11.  
12.   { TForm1 }
13.  
14.   TForm1 = class(TForm)
15.     Button1: TButton;
16.     procedure Button1Click(Sender: TObject);
17.   private
18.     FForm: TForm;
19.     procedure TimerEvent(Sender: TObject);
20.     procedure ClickEvent(Sender: TObject);
21.     procedure ShowOneliner(const AString: string; const AFont: TFont);
22.   public
23.  
24.   end;
25.  
26. var
27.   Form1: TForm1;
28.  
29. implementation
30.  
31. {$R *.lfm}
32.  
33. procedure TForm1.TimerEvent(Sender: TObject);
34. begin
35.   if (Sender is TTimer) then
36.     (Sender as TTimer).Enabled := False;
37.   FForm.Close;
38. end;
39.  
40. procedure TForm1.ClickEvent(Sender: TObject);
41. begin
42.   if ((Sender is TForm) or (Sender is TLabel)) then
43.     FForm.Close;
44. end;
45.  
46. procedure TForm1.ShowOneliner(const AString: string; const AFont: TFont);
47. var
48.   LBMP: TBitmap;
49.   LLabel: TLabel;
50.   i, LWidth, LHeight: Integer;
51.   LTimer: TTimer;
52. begin
53.   LBMP := TBitmap.Create;
54.   try
55.     LBMP.Canvas.Font := AFont;
56.     LHeight := LBMP.Canvas.TextHeight(AString);
57.     LWidth := LBMP.Canvas.TextWidth(AString);
58.   finally
59.     LBMP.Free;
60.   end;
61.   FForm := TForm.Create(nil);
62.   try
63.     FForm.Parent := nil;
64.     FForm.Visible := False;
65.     FForm.BorderIcons := [];
66.     FForm.BorderStyle := bsNone;
67.     FForm.FormStyle := fsStayOnTop;
68.     FForm.Width := LWidth + 10;
69.     FForm.Height := LHeight + 10;
70.     FForm.Left := (Screen.Width - FForm.Width) div 2;
71.     FForm.Top := (Screen.Height - FForm.Height) div 2;
72.     FForm.OnClick := ClickEvent;
73.     LLabel := TLabel.Create(FForm);
74.     try
75.       LLabel.Parent := FForm;
76.       LLabel.Visible := False;
77.       LLabel.Left := 5;
78.       LLabel.Top := 5;
79.       LLabel.Font := AFont;
80.       LLabel.Caption := AString;
81.       LLabel.Visible := True;
82.       LLabel.OnClick := ClickEvent;
83.       LTimer := TTimer.Create(FForm);
84.       try
85.         LTimer.Interval := 5000;
86.         LTimer.OnTimer := TimerEvent;
87.         LTimer.Enabled := True;
88.       finally
89.       end;
90.     finally
91.       i := FForm.ShowModal;
92.     end;
93.   finally
94.     LLabel.Free;
95.     LTimer.Free;
96.     FForm.Free;
97.   end;
98. end;
99.  
100. procedure TForm1.Button1Click(Sender: TObject);
101. begin
102.   ShowOneliner('test...', Self.Font);
103. end;
104.  
105. end.