给 TComboBox 添加图标 回复 "heyongan" 的问题

首先: 这有现成的控件: TComboBoxEx, 没必要使用 TComboBox; 非要在 TComboBox 基础上添加, 也可以.

---

本例效果图:

---

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.

窗体文件:

---

object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'Form1'
  ClientHeight = 149
  ClientWidth = 222
  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 ComboBox1: TComboBox
    Left = 24
    Top = 8
    Width = 145
    Height = 21
    ItemHeight = 13
    TabOrder = 0
    OnDrawItem = ComboBox1DrawItem
  end
  object ImageList1: TImageList
    Left = 48
    Top = 48
    Bitmap = {
      494C010104000A00040010001000FFFFFFFFFF00FFFFFFFFFFFFFFFF424D3600
      0000000000003600000028000000400000002000000001002000000000000020
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