Рисование в PaintBox

unit Unit1;
 
interface
 
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, ExtCtrls;
 
type
  TForm1 = class(TForm)
    Panel1: TPanel;
    PaintBox1: TPaintBox;
    procedure PaintBox1MouseMove(Sender: TObject; Shift: TShiftState; X,
      Y: Integer);
  procedure PaintBox1MouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure PaintBox1MouseUp(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
 
var
  Form1: TForm1;
  StartX, StartY :integer;
 
implementation
 
{$R *.dfm}
 
procedure TForm1.PaintBox1MouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  PaintBox1.Canvas.Pen.Color := clred;
  StartX := X;
  StartY := Y;
end;
 
procedure TForm1.PaintBox1MouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
begin
if not (ssLeft in Shift) then
    Exit;
  with PaintBox1.Canvas do begin
    MoveTo (StartX, StartY);
    PaintBox1.Refresh;
    Ellipse(StartX,StartY,X,Y);
  end;
end;
 
 
procedure TForm1.PaintBox1MouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
   PaintBox1.Canvas.Ellipse(StartX,StartY,X,Y);
end;
 
end.