unit Unit1;
interface
uses
 Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
 Dialogs, ToolWin, ComCtrls, ExtCtrls;
type
 TForm1 = class(TForm)
  Image1: TImage;
  procedure FormCreate(Sender: TObject);
  procedure FormMouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
  procedure FormMouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
  procedure FormMouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
 private
  { Private declarations }
  StartX: integer;
  StartY: integer;
  EndX: integer;
  EndY: integer;
  isMousePressed: boolean;
 public
  { Public declarations }
 end;
var
 Form1: TForm1;
implementation
{$R *.dfm}
procedure TForm1.FormCreate(Sender: TObject);
begin
 isMousePressed:=false;
 Image1.Picture.Bitmap:=TBitmap.create();
 Image1.Picture.Bitmap.Width:=Image1.Width;
 Image1.Picture.Bitmap.Height:=Image1.Height
end;
procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
 Shift: TShiftState; X, Y: Integer);
begin
 StartX:=X;
 StartY:=Y;
 EndX:=StartX;
 EndY:=StartY;
 isMousePressed:=true
end;
procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton;
 Shift: TShiftState; X, Y: Integer);
begin
 isMousePressed:=false;
 Image1.Picture.Bitmap.Canvas.Pen.Mode:=pmNOT;
 Image1.Picture.Bitmap.Canvas.moveTo(StartX, StartY);
 Image1.Picture.Bitmap.Canvas.lineTo(EndX, EndY);
 Image1.Picture.Bitmap.Canvas.Pen.Mode:=pmCopy;
 EndX:=X;
 EndY:=Y;
 Image1.Picture.Bitmap.Canvas.moveTo(StartX, StartY);
 Image1.Picture.Bitmap.Canvas.lineTo(EndX, EndY)
end;
procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
 Y: Integer);
begin
 if isMousePressed then
 begin
 Image1.Picture.Bitmap.Canvas.Pen.Mode:=pmNOT;
 Image1.Picture.Bitmap.Canvas.moveTo(StartX, StartY);
 Image1.Picture.Bitmap.Canvas.lineTo(EndX, EndY);
 EndX:=X;
 EndY:=Y;
 Image1.Picture.Bitmap.Canvas.moveTo(StartX, StartY);
 Image1.Picture.Bitmap.Canvas.lineTo(EndX, EndY);
 Image1.Picture.Bitmap.Canvas.Pen.Mode:=pmCopy
 end
end;
end.