MDI添加背景

[fantasyboy]

请问如何在MDI中加入背景？
谢谢！

[facedge]

在主窗体添加Image1:TImage控件，并设Picture属性。
添加定义：
private
{ Private declarations }
FClientInstance,
FPrevClientProc : TFarProc;
PROCEDURE ClientWndProc(VAR Message: TMessage);
添加实现：
procedure TForm1.ClientWndProc(var Message: TMessage);
VAR
MyDC : hDC;
Ro, Co : Word;
begin
with Message do
case Msg of
WM_ERASEBKGND:
begin
MyDC := TWMEraseBkGnd(Message).DC;
FOR Ro := 0 TO ClientHeight DIV Image1.Picture.Height DO
FOR Co := 0 TO ClientWIDTH DIV Image1.Picture.Width DO
BitBlt(MyDC, Co*Image1.Picture.Width, Ro*Image1.Picture.Height,
Image1.Picture.Width, Image1.Picture.Height,
Image1.Picture.Bitmap.Canvas.Handle, 0, 0, SRCCOPY);
Result := 1;
end;
else
Result := CallWindowProc(FPrevClientProc, ClientHandle, Msg, wParam, lParam);
end;
end;
处理创建事件：
procedure TForm1.FormCreate(Sender: TObject);
begin
FClientInstance := MakeObjectInstance(ClientWndProc);
FPrevClientProc := Pointer(GetWindowLong(ClientHandle, GWL_WNDPROC));
SetWindowLong(ClientHandle, GWL_WNDPROC, LongInt(FClientInstance));
end;
怎么样，解决了吧？！

[facedge]

完整代码(MDI主窗口):

unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, ExtCtrls;

type
TFrm_MDIMain = class(TForm)
Image1: TImage;
procedure FormCreate(Sender: TObject);
private
{ Private declarations }
FClientInstance,
FPrevClientProc : TFarProc;
PROCEDURE ClientWndProc(VAR Message: TMessage);

public
{ Public declarations }
end;

var
Frm_MDIMain: TFrm_MDIMain;

implementation

{$R *.dfm}

procedure TFrm_MDIMain.ClientWndProc(var Message: TMessage);
VAR
MyDC : hDC;
Ro, Co : Word;
begin
with Message do
case Msg of
WM_ERASEBKGND:
begin
MyDC := TWMEraseBkGnd(Message).DC;
FOR Ro := 0 TO ClientHeight DIV Image1.Picture.Height DO
FOR Co := 0 TO ClientWIDTH DIV Image1.Picture.Width DO
BitBlt(MyDC, Co*Image1.Picture.Width, Ro*Image1.Picture.Height,
Image1.Picture.Width, Image1.Picture.Height,
Image1.Picture.Bitmap.Canvas.Handle, 0, 0, SRCCOPY);
Result := 1;
end;
else
Result := CallWindowProc(FPrevClientProc, ClientHandle, Msg, wParam, lParam);
end;
end;

procedure TFrm_MDIMain.FormCreate(Sender: TObject);
begin
FClientInstance := MakeObjectInstance(ClientWndProc);
FPrevClientProc := Pointer(GetWindowLong(ClientHandle, GWL_WNDPROC));
SetWindowLong(ClientHandle, GWL_WNDPROC, LongInt(FClientInstance));
end;

end.

Delphi5/6+Win2000中通过。

[facedge]

我知道你的问题了。
你好像没有注意到我的帖子上有一句“在主窗体添加Image1:TImage控件，并设置Picture属性”。原因是你没有选择Image1的Picture属性。必须为Picture属性选择一个图片，否则就会出现上述错误，我已经试过了。
怎么样，解决了吧？！