Show Popupmenu above button

[Ericktux]

Good day my friends, how can i show popupmenu over button ? 

[Handoko]

You cannot control how popup shows up, the position and size depend on the amount of the popup items.

Except you write your own custom-made popup component. Or creating a form that behaves like a popup. Try my custompopup.zip:

Code: Pascal  [Select][+][-]

1. unit unit2;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   Forms, Controls, StdCtrls;
9.  
10. type
11.  
12.   { TfrmPopup }
13.  
14.   TfrmPopup = class(TForm)
15.     ListBox1: TListBox;
16.     procedure ListBox1DblClick(Sender: TObject);
17.     procedure ListBox1KeyPress(Sender: TObject; var Key: char);
18.   public
19.     Selected: Integer; // -1 means cancelled
20.   end;
21.  
22. var
23.   frmPopup: TfrmPopup;
24.  
25. implementation
26.  
27. {$R *.lfm}
28.  
29. { TfrmPopup }
30.  
31. procedure TfrmPopup.ListBox1KeyPress(Sender: TObject; var Key: char);
32. begin
33.   case Key of
34.     #27: begin
35.          Selected := -1;
36.          Close;
37.          end;
38.     #13: begin
39.          Selected := ListBox1.ItemIndex;
40.          Close;
41.          end;
42.   end;
43. end;
44.  
45. procedure TfrmPopup.ListBox1DblClick(Sender: TObject);
46. const
47.   C: Char = #13;
48. begin
49.   ListBox1KeyPress(Self, C);
50. end;
51.  
52. end.

I tested the code on Ubuntu Mate. The appearance may be different on Windows.

=== edit ===
Actually, we can control the X, Y positions of a TPopupMenu to show up. But the problem is, if the list contains a lot of items, the position will be changed automatically to able to show on your screen. Here are the calculations:
Popup.Top := Button1.Top + Button1.Height + Form1.Top - Popup.Height;
Popup.Left := Button1.Left + Form1.Left;     

[Ondrej Pokorny]

You cannot control how popup shows up

At least with WinAPI you can tell the popup menu where to show. See https://msdn.microsoft.com/de-de/library/windows/desktop/ms648003(v=vs.85).aspx.

[Handoko]

TPopupMenu has Popup(X, Y: Integer). The problem is we can not be sure to know the TPopup.Height, which is needed to calculate the exact position. See the calculation I provided on my previous post.

[Ondrej Pokorny]

On Windows you can do everything. Popup(X, Y: Integer) calls TrackPopupMenu/TrackPopupMenuEx as well. So you only need to write your own PopupEx function with custom parameters.

You can also calculate the menu height. (That is more advanced.)

[rvk]

On Windows you can do everything. Popup(X, Y: Integer) calls TrackPopupMenu/TrackPopupMenuEx as well. So you only need to write your own PopupEx function with custom parameters.

Yep, i.e. something like this:
(no need for height calculations with TPM_BOTTOMALIGN)

Code: Pascal  [Select][+][-]

1. uses Windows, Types;
2.  
3. procedure TForm1.Button1Click(Sender: TObject);
4. const
5.   Flags: array[boolean, TPopupAlignment] of word =
6.     ((TPM_LEFTALIGN, TPM_RIGHTALIGN, TPM_CENTERALIGN),
7.     (TPM_RIGHTALIGN, TPM_LEFTALIGN, TPM_CENTERALIGN));
8.   Buttons: array[TTrackButton] of word = (TPM_RIGHTBUTTON, TPM_LEFTBUTTON);
9. var
10.   AFlags: integer;
11.   P: TPoint;
12. begin
13.   AFlags := Flags[UseRightToLeftAlignment, PopupMenu1.Alignment] or
14.     Buttons[PopupMenu1.TrackButton] or TPM_BOTTOMALIGN;
15.   P := Button1.ClientToScreen(Types.Point(0, 0));
16.   TrackPopupMenu(PopupMenu1.Items.Handle, AFlags, P.X, P.Y, 0, Button1.Handle, nil);
17. end;

[Ericktux]

Thanks friends for your answers, Your codes can also be used in linux ?

[rvk]

Your codes can also be used in linux ?

Nope, for linux you need to follow Handoko's instructions and calculate the height and set the x and y positions so the popup can dropdown to just above the button.

[Ericktux]

hi my friends, I noticed than moving the form down The popupmenu is shown above. 
But if the form moves it above the popupmenu comes down. 

i use this code:

Code: Pascal  [Select][+][-]

1. procedure TForm1.Button1Click(Sender: TObject);
2. begin
3.     with Button1.ClientToScreen(point(0, 0)) do
4.      PopupMenu1.Popup(X, Y);
5. end;

I'll use it for the moment.
Thanks friends for your help