Graphic Delphi

Title: How to adjust the Windowform to a TCanvas
var
Form1: TForm1;
HRgn: THandle;
implementation
{$R *.DFM}
procedure TForm1.Button1Click(Sender: TObject);
var
s: string;
begin
DeleteObject(HRgn);
s := InputBox('Region Text', 'Please enter some text to set to the region', 'CoolRgn');
BeginPath(Canvas.Handle);
with Canvas do
begin
Font.Name := 'Comic Sans MS';
Font.Size := 64;
Font.Style := [fsBold];
TextOut(0, 0, s);
end;
EndPath(Canvas.Handle);
HRgn := PathToRegion(Canvas.Handle);
SetWindowRgn(Handle, HRgn, True);
button1.Visible := False;
Color := clRed;
end;
procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
DeleteObject(HRgn);
end;
procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
if Button = mbLeft then
begin
ReleaseCapture;
SendMessage(Handle, WM_NCLBUTTONDOWN, HTCAPTION, 0);
end;
end;