给MDI主窗口加图片(strectch)
给MDI主窗口加图片(strectch)
将Form1的FormStyle设置为fsMDIForm，设置成MDI的主窗口。
加入image1，并调入一幅图片
在Form1的Private中定义：
FClientInstance,FPrevClientProc : TFarProc;
PROCEDURE ClientWndProc(VAR Message: TMessage);
在Form1的创建事件中加入：
FClientInstance := MakeObjectInstance(ClientWndProc);
FPrevClientProc := Pointer(GetWindowLong(ClientHandle, GWL_WNDPROC));
SetWindowLong(ClientHandle, GWL_WNDPROC, LongInt(FClientInstance));
实现过程：
PROCEDURE TForm1.ClientWndProc(VAR Message: TMessage);
VAR
CanvasClient:TCanvas;
begin
with Message do
case Msg of
WM_ERASEBKGND:
begin
CanvasClient:=Tcanvas.Create;
CanvasClient.Handle:=GetDC(self.ClientHandle);
CanvasClient.StretchDraw(rect(0,0,clientwidth,clientheight),image1.Picture.Bitmap);
CanvasClient.Free;
end;
else
Result := CallWindowProc(FPrevClientProc, ClientHandle, Msg, wParam, lParam);
end;
end;
