delphi 给 TComboBox 添加图标

代码文件:

unit Unit1;

interface

uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs, StdCtrls, ImgList, ComCtrls;

type

  TForm1 = class(TForm)

    ComboBox1: TComboBox;

    ImageList1: TImageList;

    procedure FormCreate(Sender: TObject);

    procedure ComboBox1DrawItem(Control: TWinControl; Index: Integer;

      Rect: TRect; State: TOwnerDrawState);

    procedure FormDestroy(Sender: TObject);

  end;

var

  Form1: TForm1;

implementation

{$R *.dfm}

var

  Bits: array[0..3] of TBitmap;

procedure TForm1.FormCreate(Sender: TObject);

var

  i: Integer;

begin

  for i := 0 to Length(Bits)-1 do

  begin

    Bits[i] := TBitmap.Create;

    ImageList1.GetBitmap(i, Bits[i]);

    ComboBox1.Items.Add(Format('Item %d', [i]));

  end;

  ComboBox1.Style := csOwnerDrawVariable;

  ComboBox1.ItemHeight := Bits[0].Height + 4;

  ComboBox1.ItemIndex := 0;

end;

procedure TForm1.ComboBox1DrawItem(Control: TWinControl; Index: Integer;

  Rect: TRect; State: TOwnerDrawState);

begin

  ComboBox1.Canvas.FillRect(Rect);

  ComboBox1.Canvas.BrushCopy(Bounds(Rect.Left+2, Rect.Top+2, Bits[Index].Width, Bits[Index].Height), 

                             Bits[Index],

                             Bounds(0, 0, Bits[Index].Width, Bits[Index].Height),

                             clBlack);

  ComboBox1.Canvas.TextOut(Rect.Left + 24, Rect.Top + 3, ComboBox1.Items[Index]);

end;

procedure TForm1.FormDestroy(Sender: TObject);

var

  i: Integer;

begin

  for i := 0 to Length(Bits)-1 do

    Bits[i].Free;

end;

end.