unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    DXPaintBox1: TDXPaintBox;
    procedure FormCreate(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
const
  ImgPath1 = 'C:\Temp\DX.jpg';
begin
  DXPaintBox1.DIB.LoadFromFile(ImgPath1);
  DXPaintBox1.Width := DXPaintBox1.DIB.Width;
  DXPaintBox1.Height := DXPaintBox1.DIB.Height;
  DXPaintBox1.DIB.AntialiasedLine(0, 0, DXPaintBox1.Width, DXPaintBox1.Height, clRed);
  DXPaintBox1.DIB.AntialiasedLine(0, DXPaintBox1.Height, DXPaintBox1.Width, 0, clRed);
end;

end.