我想在Canvas上使用区域来检测鼠标在其上的移动，但是我无法使CreatePolygonRgn()正常工作。
下面是一个示例代码：

var
  regs : array of HRGN;

procedure TForm8.Button1Click(Sender: TObject);
var
  n : integer;
  p : array[0..3] of integer;
begin
  SetLength(regs, 10);
  for n := 1 to Length(regs) do try
    p[0] := n*50-20;
    p[1] := n*50+20;
    p[2] := n*50+20;
    p[3] := n*50-20;
    regs[n-1] := CreatePolygonRgn(p[0], 2 {neither with 4}, 1); // seems not working as expected
    // regs[n-1] := CreateRectRgn(p[0], p[1], p[2], p[3]); // this works

    FillRgn(image.Canvas.Handle, regs[n-1], image.Canvas.Brush.Handle); // doesn't draw anything             
  except
    ShowMessage('error creating region');
  end;
  Application.ProcessMessages;
end;

procedure TForm8.ImageMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
begin
  if (ssCtrl in Shift) then begin
    for var i : integer := 0 to Length(regs)-1 do
      if PtInRegion(regs[i], X, Y) then begin // works only with CreateRectRgn 
        ShowMessage('region ' + IntToStr(i));
        break;
      end;
  end;
end;

我做错了什么？