c.Handle:=GetDC(h);这句代码老是报：Incompatible types: 'QPainterH' and 'HDC'

 c.Handle:=GetDC(h);  这句代码老是报编译错误：Incompatible types: 'QPainterH' and 'HDC'这个怎么解决啊？？功能是实现截取当前活动窗口。源代码如下（网络找的）：var
      b:TBitMap;
      c:TCanvas;
      r:TRect;
      h:THandle;
  begin
  b:=nil;
  c:=nil;
  try
      b:=TBitMap.Create;
      c:=TCanvas.Create;
      h:=GetActiveWindow;
      c.Handle:=GetDC(h);
      GetWindowRect(h,r);
      with   r   do   r:=Rect(0,0,Right-Left,Bottom-Top);
      b.Width:=r.Right;
      b.Height:=r.Bottom;
      b.Canvas.CopyRect(r,c,r);
      b.SaveToFile('C:\x.bmp');
  finally
      b.Free;
      c.Free;
  end;
  end;