复制文件时，如何显示进度条

procedure mycopyfile(sourcef,targetf:string;i:integer);
var
       FromF,ToF:file;
       NumRead,NumWritten:Integer;
       Buf:array[1..2048] of Char;
       n:integer;
begin
         AssignFile(FromF,sourcef);
         Reset(FromF,    1); {    Record    size    =    1    }
         AssignFile(ToF,targetf); {    Open    output    file    }
         Rewrite(ToF,    1); {    Record    size    =    1    }
         n:=0;  
         repeat
                   BlockRead(FromF,    Buf,    SizeOf(Buf),    NumRead);
                   form1.:=sizeof(buf)*n*100    div    FileSize(FromF)*i div 4;
                   ;
                   //显示进度
                   BlockWrite(ToF,    Buf,    NumRead,    NumWritten);
                   inc(n);
           until    (NumRead    =    0)    or    (NumWritten    <>    NumRead);
           form1.:=100;
           CloseFile(FromF);
           CloseFile(ToF);
end;
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以下例子是关于delphi复制文件，加上进度条的方法的例子的关键代码:

procedure TForm1.Button1Click(Sender: TObject);
const
  getPath = 'c:/temp/';
  setPath = 'c:/temp/';
var
  getStream,setStream: TFileStream;
  num, n: Integer;
  buf: PByte;
  BufSize,block: Integer;
begin

  if not FileExists(getPath) then
  begin
    ShowMessage('源文件不存在');
    Exit;
  end;

  getStream := (getPath, fmOpenRead or fmShareExclusive);
  setStream := (setPath, fmCreate);

  num := ;
  := num;
  := 0;
  := 0;

  BufSize := num;
  block := BufSize div 100;
  GetMem(buf, BufSize);

  := 100;
  := 0;
  := 0;

  while num <> 0 do
  begin
    ;
    n := block;
    if n > num then n := num;
    (buf^, n);
    (buf^, n);
    := Trunc((1 - num / BufSize) * 100);
    Dec(num, n);
  end;

  FreeMem(buf, BufSize);
  ;
  ;

  ShowMessage('复制完毕');
  := 0;
end;

end.