1   
2   unit Unit1;
3   
4   interface
5   
6   uses
7     Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
8     Dialogs, StdCtrls;
9   
10  type
11    TForm1 = class(TForm)
12      Button1: TButton;
13      procedure Button1Click(Sender: TObject);
14    private
15      { Private declarations }
16    public
17      { Public declarations }
18    end;
19  
20  var
21    Form1: TForm1;
22  
23  implementation
24  
25  {$R *.dfm}
26  
27  procedure TForm1.Button1Click(Sender: TObject);
28  
29  var
30    DevMode: TDeviceMode;
31  begin
32    EnumDisplaySettings( nil, 0, DevMode );
33    DevMode.dmFields := DM_PELSWIDTH or DM_PELSHEIGHT;
34    DevMode.dmPelsWidth := 1024;
35    DevMode.dmPelsHeight := 768;
36  if ChangeDisplaySettings(DevMode, CDS_UPDATEREGISTRY)
37    = DISP_CHANGE_SUCCESSFUL then
38   showmessage('Unable to change screen resolution');
39   else
40   showmessage('Success!');
41  
42  end;
43  
44  end.