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.
7. 覆盖ComboBox的OnMeasureItem.
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:\delphi\images\buttons\globe.bmp);
TheBitmap2 := TBitmap.Create;
TheBitmap2.LoadFromFile(C:\delphi\images\buttons\video.bmp);
TheBitmap3 := TBitmap.Create;
Th
tmap3.LoadFromFile(C:\delphi\images\buttons\gears.bmp);
TheBitmap4 :=
TBitmap.Create;
TheBitmap4.LoadFromFile(C:\delphi\images\buttons\key.bmp);
TheBitmap5 := TBitmap.Create;
TheBitmap5.LoadFromFile(C:\delphi\images\buttons\tools.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
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