在Listbox中增加背景图_编程语言综合--HTML5中文学习网

　1. 建立一个窗体
2. 放一个ComboBox和Listbox
3. 改变Component的Style为csOwnerDrawVariable和ListBox的Style为lbOwnerDrawVariable。
4. 声明5个TBitmap的全局变量
5. 覆盖Form的OnCreate.
6. 覆盖ComboBox的OnDraw.
7. 覆盖ComboBox的OnMeasureItem.
8. 释放资源在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.AddObject('Bitmap1: Globe', TheBitmap1);
ComboBox1.Items.AddObject('Bitmap2: Video', TheBitmap2);
ComboBox1.Items.AddObject('Bitmap3: Gears', TheBitmap3);
ComboBox1.Items.AddObject('Bitmap4: Key', TheBitmap4);
ComboBox1.Items.AddObject('Bitmap5: Tools', TheBitmap5);
ListBox1.Items.AddObject('Bitmap1: Globe', TheBitmap1);
ListBox1.Items.AddObject('Bitmap2: Video', TheBitmap2);
ListBox1.Items.AddObject('Bitmap3: Gears', TheBitmap3);
ListBox1.Items.AddObject('Bitmap4: Key', TheBitmap4);
ListBox1.Items.AddObject('Bitmap5: Tools', TheBitmap5);

　　end;

　　procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
TheBitmap1.Free;
TheBitmap2.Free;
TheBitmap3.Free;
TheBitmap4.Free;
TheBitmap5.Free;
end;

　　procedure TForm1.ComboBox1DrawItem(Control: TWinControl; Index: Integer;
Rect: TRect; State: TOwnerDrawState);
var
Bitmap: TBitmap;
Offset: Integer;
begin
with (Control as TComboBox).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;
    { display the text }
    TextOut(Rect.Left + Offset, Rect.Top, Combobox1.Items[Index])
end;
end;

　　procedure TForm1.ComboBox1MeasureItem(Control: TWinControl; Index:
Integer; var Height: Integer);
begin
height:= 20;
end;

　　procedure TForm1.ListBox1DrawItem(Control: TWinControl; Index: Integer;
Rect: TRect; State: TOwnerDrawState);
var
Bitmap: TBitmap;
Offset: Integer;
begin
with (Control as TListBox).Canvas do
begin
    FillRect(Rect);
    Bitmap := TBitmap(ListBox1.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;
    { display the text }
    TextOut(Rect.Left + Offset, Rect.Top, Listbox1.Items[Index])
end;
end;

　　procedure TForm1.ListBox1MeasureItem(Control: TWinControl; Index: Integer;
var Height: Integer);
begin
height:= 20;
end;

　　end.

　　
//该窗体的DFM文件

　　object Form1: TForm1
Left = 211
Top = 155
Width = 435
Height = 300
Caption = 'Form1'
Font.Color = clWindowText
Font.Height = -13
Font.Name = 'System'
Font.Style = []
PixelsPerInch = 96
OnClose = FormClose
OnCreate = FormCreate
TextHeight = 16
object ComboBox1: TComboBox
    Left = 26
    Top = 30
    Width = 165
    Height = 22
    Style = csOwnerDrawVariable
    ItemHeight = 16
    TabOrder = 0
    OnDrawItem = ComboBox1DrawItem
    OnMeasureItem = ComboBox1MeasureItem
end
object ListBox1: TListBox
    Left = 216
    Top = 28
    Width = 151
    Height = 167
    ItemHeight = 16
    Style = lbOwnerDrawVariable
    TabOrder = 1
    OnDrawItem = ListBox1DrawItem
    OnMeasureItem = ListBox1MeasureItem
end
end