unit Unit1;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, StdCtrls,
  ExtCtrls, Spin, ColorBox;

type

  { TForm1 }

  TForm1 = class(TForm)
    btnClean: TButton;
    bcolor: TColorButton;
    Button1: TButton;
    Button2: TButton;
    Image1: TImage;
    bsize: TSpinEdit;
    procedure btnCleanClick(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Image1MouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure Image1MouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer
      );
  private
    { private declarations }
  public
    { public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.lfm}

{ TForm1 }

procedure TForm1.btnCleanClick(Sender: TObject);
begin
  Image1.Canvas.Clear;
  Image1.Canvas.Pen.Color:=clBlack;
  Image1.Canvas.Brush.Color:=clWhite;
end;

//Vytvoríme si plátno
//Vytvoríme event: MouseDown a MouseMove pre plátno
//Do eventu MouseDown "naprogramujeme" začiatok kreslenia
//Do eventu MouseMove naprogramujeme samotné kreslenie a mazanie a ďalšie nastavenia

procedure TForm1.Image1MouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  Image1.Canvas.MoveTo(X,Y); //Po kliknutí na plátno "kurzor" skočí na naše zvolené miesto X,Y
end;

procedure TForm1.Image1MouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
begin
  Image1.Canvas.Pen.Width:=bsize.Value; //Nastavenie veľkosti písma
  Image1.Canvas.Pen.Color:=bcolor.Buttoncolor; //Nastavenie farby písma
  if Shift = [ssLeft] then Image1.Canvas.LineTo(X,Y); //ak je ľavé tlačidlo na myši stisknuté tak sa začne kresliť
  if Shift = [ssRight] then //ak je pravé tlačidlo na myši stisknuté tak sa začne mazať
    begin
      Image1.Canvas.Pen.Color:=clWhite; //Farba gumy. logicky biela. Ak máte pozadie inej farby tak nezadavajte bielu
      Image1.Canvas.Ellipse(X+5,Y+5,X-5,Y-5); //Vytvorenie kruhu pomocou ktorého budeme mazať
    end;
end;

procedure TForm1.Button1Click(Sender: TObject);//Prvý spôsob polygonu
begin
  Image1.Canvas.Clear; //Vyčistí plátno
  Image1.Canvas.Pen.Color:=clBlue; //Nastaví farbu pera na modrú
  Image1.Canvas.Pen.Width:=5; //Nastaví hrúbku pera na 5
  Image1.Canvas.Brush.Color:=clGreen; //Nastaví výplň objektu na zelenú
  Image1.Canvas.Polygon([Point(Image1.Width div 2,0),Point(0,Image1.Height-1),Point(Image1.Width,Image1.Height-1)]);
  Image1.Canvas.Pen.Color:=clBlack; //Resetovanie
  Image1.Canvas.Brush.Color:=clWhite; //Resetovanie
  Image1.Canvas.Pen.Width:=1; //Resetovanie
end;

procedure TForm1.Button2Click(Sender: TObject);//Druhý spôsob polygonu
var Bod: array of TPoint; //Definícia poľa
begin
  Image1.Canvas.Clear; //Vyčistí plátno
  Image1.Canvas.Pen.Color:=clBlue; //Nastaví farbu pera na modrú
  Image1.Canvas.Pen.Width:=5; //Nastaví hrúbku pera na 5
  Image1.Canvas.Brush.Color:=clGreen; //Nastaví výplň objektu na zelenú
  SetLength(bod, 3); //Nastavenie veľkosti poľa
  bod[0]:=Point(Image1.Width div 2, 0);
  bod[1]:=Point(0, Image1.Height-1);
  bod[2]:=Point(Image1.Width, Image1.Height-1);
  Image1.Canvas.Polygon(bod);
  Image1.Canvas.Pen.Color:=clBlack; //Resetovanie
  Image1.Canvas.Brush.Color:=clWhite; //Resetovanie
  Image1.Canvas.Pen.Width:=1; //Resetovanie
end;

end.