sos

这是一个带图标的组合框，通过编译但是图标显示不出来阿~~
请帮我看看怎么回事情~~谢谢
unit unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;
type
   TForm1 = class(TForm)
   ComboBox1: TComboBox;
    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);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Form1: TForm1;
  MyBitmap1,Mybitmap2:TBitMap;
implementation{$R *.dfm}procedure TForm1.FormCreate(Sender:TObject);
begin
  MyBitmap1:=TBitmap.Create;
  MyBitmap1.LoadFromFile('3.bmp');
  MyBitmap2:=TBitmap.Create;
  MyBitmap2.LoadFromFile('4.bmp');
  ComboBox1.Items.AddObject('Bitmap1', MyBitmap1);
  ComboBox1.Items.AddObject('Bitmap2', MyBitmap2);
end;procedure TForm1.FormClose(Sender:TObject;var Action:TCloseAction);
begin
  MyBitmap1.Free;
  MyBitmap2.Free;
end;procedure TForm1.ComboBox1DrawItem(Control:TWinControl;Index:Integer;
 Rect:TRect;State:TOwnerDrawState);
  var Bitmap: TBitmap; Offset: Integer;
 begin
   offset:=0;
   with ComboBox1.Canvas do
   begin
     FillRect(Rect);
     Bitmap:=TBitmap(ComboBox1.Items.Objects[Index]);
     if Bitmap <> nil then
     begin
       BrushCopy(Bounds(Rect.Left+2,Rect.Top+2,Bitmap.Width,
       Bitmap.Height),Bitmap,Bounds(0,0,Bitmap.Width,
       Bitmap.Height),clred);       Offset:=Bitmap.width+8;
     end;     TextOut(Rect.Left+Offset,Rect.Top,ComboBox1.Items[Index]);
   end;
 end; procedure TForm1.ComboBox1MeasureItem(Control:TWinConTrol;
 Index:Integer;var Height:Integer);
 begin
   height:=100;
  end;
end.