unit DAngle;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.ExtCtrls;

type
  TDlgAngle = class(TForm)
  private
    { Private declarations }
  public
    { Public declarations }
    procedure ShowAngle(const aRect: TRect);
  end;

var
  DlgAngle: TDlgAngle;

implementation

{$R *.dfm}

procedure TDlgAngle.ShowAngle(const aRect: TRect);
var
  RectRgn1,
  RectRgn2,
  RectRgn3 : THandle;
  Monitor: TMonitor;
//  x, y  : integer;
begin
//  x := Width - ClientWidth;
//  y := Height - ClientHeight;
//  hEllipse := CreateEllipticRgn(x, y, ClientWidth, ClientHeight);

  Left := aRect.Left;
  Top := aRect.Top;
  Width := aRect.Right - aRect.Left;
  Height := aRect.Bottom - aRect.Top;

  RectRgn1 := CreateRectRgn(0, 0, Width, Height);
  RectRgn2 := CreateRectRgn(0, 0, Width, Height);
  RectRgn3 := CreateRectRgn(10, 10, Width-10, Height-10);
  CombineRgn(RectRgn1, RectRgn2, RectRgn3, RGN_XOR);
  SetWindowRgn(Handle, RectRgn1, True);
  DeleteObject(RectRgn1);
  DeleteObject(RectRgn2);
  DeleteObject(RectRgn3);

  Show;
end;

end.