unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, ExtCtrls, ComCtrls;

type
TForm1 = class(TForm)
Timer1: TTimer;
procedure Timer1Timer(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Timer1Timer(Sender: TObject);
var
px,py : Integer;
Pscreen : hdc;
can : tcanvas;
p : TPoint;
begin
Pscreen:=getdc(0);
can:=tcanvas.Create;
can.Handle:=Pscreen;
can.Brush.style:=bsclear;
can.Pen.color:=clwindow;
can.Pen.Width := 8;
GetCursorPos(P); //得到鼠标坐标
px := p.X;
py := p.Y;
can.Ellipse(px-3,py-3,px+3,py+3);
can.Free;
releasedc(0,Pscreen);
end;

运行该程序后，关闭该程序的操作步骤如下：
步骤1：按键。
步骤2：单击“任务管理器”按钮。
步骤3：选中该程序的可执行文件“Project1”，单击“结束进程”即可。