unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, ExtCtrls, StdCtrls, Unit2;

type
  TForm1 = class(TForm)
    PaintBox1: TPaintBox;
    ColorDialog1: TColorDialog;
    Button1: TButton;
    FontDialog1: TFontDialog;
    Button2: TButton;
    Button3: TButton;
    procedure PaintBox1Paint(Sender: TObject);
    procedure PaintBox1MouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure PaintBox1MouseUp(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure PaintBox1MouseMove(Sender: TObject; Shift: TShiftState; X,
      Y: Integer);
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
  private
    x1,x2,y1,y2 : integer;
    paint       : boolean;
    color       : TColor;
    fnt         : TFont;
    text        : string;
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.PaintBox1Paint(Sender: TObject);
begin

  with PaintBox1.Canvas do
  begin
    Pen.Color := color;
    Pen.Width := 5;
    Brush.Color := clBlue;

    //MoveTo(x1,y1);
    //LineTo(x2,y2);
    Rectangle(x1,y1,x2,y2);
    FillRect(Rect(x1,y1,x2,y2));

    // centruje text do stredu canvasu
    Brush.Color := clBtnFace;
    Font := fnt;

    TextOut(Width div 2 - TextWidth(text) div 2
           ,Height div 2 - TextHeight(text) div 2,text);
  end;
end;

procedure TForm1.PaintBox1MouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin

  x1 := X;
  y1 := Y;
  paint := true;
end;

procedure TForm1.PaintBox1MouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin

  paint := false;
end;

procedure TForm1.PaintBox1MouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
begin

  if paint then
  begin

    x2 := X;
    y2 := Y;
    PaintBox1.Repaint;  // znovu vykresli paintbox
  end;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin

  x1 := 0;
  x2 := 0;
  y1 := 0;
  y2 := 0;
  paint := false;
  color := clGreen;
  fnt := Form1.Font;
  text := 'A je To!';
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  ColorDialog1.Color := color;
  if ColorDialog1.Execute then
  begin
    color := ColorDialog1.Color;
    PaintBox1.Repaint;
  end;
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  FontDialog1.Font := fnt;
  if FontDialog1.Execute then
  begin
    fnt := FontDialog1.Font;
    PaintBox1.Repaint;
  end;
end;

procedure TForm1.Button3Click(Sender: TObject);
begin
  Form2.Edit1.Text := text;
  Form2.ShowModal;
  if Form2.ModalResult = mrOK then
  begin
    text := Form2.Edit1.Text;
    PaintBox1.Repaint;
  end;
end;

end.