//简单点的
//form上一个scrollbox,一个button
//在button的click事件中
procedure TForm1.Button1Click(Sender: TObject);
var
hd:hdc;
canvas:Tcanvas;
begin
canvas:=Tcanvas.Create;
hd:=getdc(self.ScrollBox1.Handle);
canvas.Handle:=hd;
canvas.Pen.Color:=clred;
canvas.MoveTo(0,0);
canvas.LineTo(333,466);
end;
//楼主看看