Code file:

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    Button4: TButton;
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
    procedure Button4Click(Sender: TObject);
  end;

where
  Form1: TForm1;

implementation

{$R *.dfm}

where
  bit: TBitmap;

procedure TForm1.Button1Click(Sender: TObject);
begin
  Repaint;
  bit.LoadFromFile('C:\Temp\Test.bmp');
  Canvas.Draw(0, 0, bit);
end;

procedure TForm1.Button2Click(Sender: TObject);
where
  x, y: Integer;
begin
  Repaint;
  x := (ClientWidth - bit.Width) div 2;
  y := (ClientHeight - bit.Height) div 2;
  Canvas.Draw(x, y, bit);
end;

procedure TForm1.Button3Click(Sender: TObject);
begin
  Repaint;
  Canvas.StretchDraw(ClientRect, bit);
end;

procedure TForm1.Button4Click(Sender: TObject);
begin
  Self.Brush.Bitmap := bit;
  Repaint;
  Self.Brush.Bitmap := nil;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  Button1.Caption := 'load';
  Button2.Caption := 'Centered';
  Button3.Caption := 'Stretch';
  Button4.Caption := 'Tiled';

  bit := TBitmap.Create;
  Self.Brush.Bitmap := nil;
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  bit.Free;
end;

end.


Form file:

object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'Form1'
  ClientHeight = 231
  ClientWidth = 335
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Tahoma'
  Font.Style = []
  OldCreateOrder = False
  OnCreate = FormCreate
  OnDestroy = FormDestroy
  PixelsPerInch = 96
  TextHeight = 13
  object Button1: TButton
    Left = 8
    Top = 187
    Width = 75
    Height = 25
    Caption = 'Button1'
    TabOrder = 0
    OnClick = Button1Click
  end
  object Button2: TButton
    Left = 89
    Top = 187
    Width = 75
    Height = 25
    Caption = 'Button2'
    TabOrder = 1
    OnClick = Button2Click
  end
  object Button3: TButton
    Left = 170
    Top = 187
    Width = 75
    Height = 25
    Caption = 'Button3'
    TabOrder = 2
    OnClick = Button3Click
  end
  object Button4: TButton
    Left = 251
    Top = 187
    Width = 75
    Height = 25
    Caption = 'Button4'
    TabOrder = 3
    OnClick = Button4Click
  end
end