Author: Jonas Bilinkevicius

How to detect a form movement

Answer:

Solve 1:

1   type
2     TForm1 = class(TForm)
3     private
4       { Private declarations }
5       procedure WMEXITSIZEMOVE(var message: TMessage); message WM_EXITSIZEMOVE;
6       procedure WMENTERSIZEMOVE(var message: TMessage); message WM_ENTERSIZEMOVE;
7   
8   implementation
9   
10  procedure TForm1.WMENTERSIZEMOVE(var message: TMessage);
11  begin
12    Form1.Caption := 'Starting moving and sizing';
13  end;
14  
15  procedure TForm1.WMEXITSIZEMOVE(var message: TMessage);
16  begin
17    Form1.Caption := 'Finished moving and sizing';
18  end;



Solve 2:

Handle the WM_MOVING or WM_WINDOWPOSCHANGING message from windows, i.e.:

19  { Private declarations }
20  
21  procedure WMWINDOWPOSCHANGING(var msg: TWMWINDOWPOSCHANGING);
22    message WM_WINDOWPOSCHANGING;
23  
24  procedure TForm1.WMWINDOWPOSCHANGING(var msg: TWMWINDOWPOSCHANGING);
25  var
26    r: TRect;
27  begin
28    if ((SWP_NOMOVE or SWP_NOSIZE) and msg.WindowPos^.flags) <> (SWP_NOMOVE
29      or SWP_NOSIZE) then
30    begin
31      { Window is moved or sized, get usable screen area }
32      { Do something here }
33    end;
34    inherited;
35  end;