在Listbox中增加背景圖

　1.  建立一個窗體
2.  放一個ComboBox和Listbox
3.  改變Component的Style為csOwnerDrawVariable和ListBox的Style為lbOwnerDrawVariable。
4.  聲明5個TBitmap的全局變量
5.  覆蓋Form的OnCreate.
6.  覆蓋ComboBox的OnDraw.
7.  覆蓋ComboBox的OnMeasureItem.
8.  釋放資源在Form的OnClose.

　　
unit Ownerdrw;

　　interface

　　uses
  SysUtils, WinTypes, WinProcs, Messages, Classes, Graphics, Controls,
  Forms, Dialogs, StdCtrls;

　　type
  TForm1 = class(TForm)
    ComboBox1: TComboBox;
    ListBox1: TListBox;
    procedure FormCreate(Sender: TObject);
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
    procedure ComboBox1DrawItem(Control: TWinControl; Index: Integer;
      Rect: TRect; State: TOwnerDrawState);
    procedure ComboBox1MeasureItem(Control: TWinControl; Index: Integer;
      var Height: Integer);
    procedure ListBox1DrawItem(Control: TWinControl; Index: Integer;
      Rect: TRect; State: TOwnerDrawState);
    procedure ListBox1MeasureItem(Control: TWinControl; Index: Integer;
      var Height: Integer);

　　  private
    { Private declarations }

　　  public
    { Public declarations }

　　  end;

　　var
  Form1: TForm1;
  TheBitmap1, TheBitmap2, TheBitmap3, TheBitmap4,
  TheBitmap5 : TBitmap;
implementation

　　{$R *.DFM}

　　procedure TForm1.FormCreate(Sender: TObject);
begin
  TheBitmap1 := TBitmap.Create;
  TheBitmap1.LoadFromFile('C:delphiimagesuttonsglobe.bmp');
  TheBitmap2 := TBitmap.Create;
  TheBitmap2.LoadFromFile('C:delphiimagesuttonsvideo.bmp');
  TheBitmap3 := TBitmap.Create;
  TheBitmap3.LoadFromFile('C:delphiimagesuttonsgears.bmp');
  TheBitmap4 := TBitmap.Create;
  TheBitmap4.LoadFromFile('C:delphiimagesuttonskey.bmp');
  TheBitmap5 := TBitmap.Create;
  TheBitmap5.LoadFromFile('C:delphiimagesuttons ools.bmp');
  ComboBox1.Items.AddObjec