type
TForm1 = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
procedure FormPaint(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
var
Form1: TForm1;
id : boolean = false;
implementation
{$R *.dfm}
procedure TForm1.Button1Click(Sender: TObject);
begin
form1.Canvas.Pen.Color := clred;
form1.canvas.MoveTo(20,20);
form1.Canvas.LineTo(40,40);
id := true;
end;
procedure TForm1.FormPaint(Sender: TObject);
begin
if id then
begin
form1.Canvas.Pen.Color := clred;
form1.canvas.MoveTo(20,20);
form1.Canvas.LineTo(40,40);
end;
end;