我的背景为什么不能显示？高分求解！！来者有份

Question

unit Unit_MDIform;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, jpeg, ExtCtrls, StdCtrls;type
  TForm1 = class(TForm)
    Image1: TImage;
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
     FclientInstance,
     FprevClientProc:TFarProc;
     procedure ClientWndProc(var MEssage:tmessage);
  public
    { Public declarations }
  end;var
  Form1: TForm1;implementation
{$R *.dfm}
 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;
procedure TForm1.FormCreate(Sender: TObject);
begin
FClientInstance:=MakeObjectInstance(clientwndProc);
FprevClientProc:=Pointer(getwindowLong(clientHandle,GWL_WNDPROC));
SetWindowLong(clientHandle,GWL_WNDPROC,longInt(FClientInstance));
end;end.

Answer 1

for Ro := 0 to clientHeight  div   Image1.Picture.Height do
    for co := 0 to Clientwidth  div Image1.Picture.Width do
这两句总是报错：division by zero

Answer 2

ft，你进入消息循环时picture对象好像还没来得及加载，
if (Image1.Picture <> null) and !(Image1.Picture.Height) and (!Image1.Picture.Width )
begin
for Ro := 0 to clientHeight  div   Image1.Picture.Height do
    for co := 0 to Clientwidth  div Image1.Picture.Width do

Answer 3

//改一下控件属性
image1.Align:=alClient;

Answer 4

你要加载bmp图，不能用jpg图，如果是jpg图也会出division by zero错误

Answer 5

to firetoucher(蹈火者）你说的不行
我试了
还是报同样的错

Answer 6

to 等你一生你说的对
我原来用的时jpg格式的