unit Unit1;

{$mode objfpc}{$H+}

interface

uses

  Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, ExtCtrls,

  StdCtrls;

type

  { TForm1 }

  TForm1 = class(TForm)

    Image1: TImage;

    Label1: TLabel;

    Shape1: TShape;

    Timer1: TTimer;

    procedure FormCreate(Sender: TObject);

    procedure Image1MouseDown(Sender: TObject; Button: TMouseButton;

      Shift: TShiftState; X, Y: Integer);

    procedure Image1MouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer

      );

    procedure Timer1Timer(Sender: TObject);

  private

    { private declarations }

  public

    { public declarations }

  end;

var

  Form1: TForm1;

  speed: single;

implementation

{$R *.lfm}

procedure TForm1.FormCreate(Sender: TObject);

begin

  Image1.Canvas.Brush.Color := clWhite;

  Image1.Canvas.FillRect(Image1.ClientRect);

end;

procedure TForm1.Image1MouseDown(Sender: TObject; Button: TMouseButton;

  Shift: TShiftState; X, Y: Integer);

begin

  if Button = mbRight then begin

    Shape1.Left := round(x - Shape1.Width/2);

    Shape1.Top := round(y - Shape1.Height/2);

    Shape1.Visible := true;

    speed := 0;

  end;

end;

procedure TForm1.Image1MouseMove(Sender: TObject; Shift: TShiftState; X,

  Y: Integer);

begin

  if ssLeft in Shift then begin

    Image1.Canvas.Pen.Width := 50;

    Image1.Canvas.Pen.Style := psSolid;

    Image1.Canvas.LineTo(x, y);

  end else begin

    Image1.Canvas.MoveTo(x, y);

  end;

end;

procedure TForm1.Timer1Timer(Sender: TObject);

var

  x, y: integer;

begin

  if Shape1.Visible then begin

    Shape1.Top := Round(Shape1.Top + speed);

    speed := speed + 1;

    if Shape1.Top > ClientHeight then Shape1.Visible := false;

    x := round(Shape1.Left + Shape1.Width/2);

    y := round(Shape1.Top + Shape1.Height/2);

    if Image1.Canvas.Pixels[x, y] = clBlack then begin

      Shape1.Visible := false;

      Image1.Canvas.Pen.Style := psClear;

      Image1.Canvas.Ellipse(round(x-speed), round(y-speed), round(x+speed), round(y+speed));

    end;

  end;

end;

end.