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lbOwnerDrawVariabble。
4. 声明5个TBitmap的全局变量
5. 覆盖Form的OnCreate.
6. 覆盖ComboBox的OnDraw.
8. 释放资源在Form的OnClose.
下面给出完整的主程序源程序：
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;
Th tmap3.LoadFromFile(C:delphiimagesuttonsgears.bmp);
TheBitmap4 := TBitmap.Create;
TheBitmap4.LoadFromFile(C:delphiimagesuttonskey.bmp);
TheBitmap5 := TBitmap.Create;
TheBitmap5.LoadFromFile(C:delphiimagesuttonsools.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
