/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsISupports.idl"

/**
 * The nsIScrollable is an interface that can be implemented by a control that
 * supports scrolling.  This is a generic interface without concern for the 
 * type of content that may be inside.
 */
[scriptable, uuid(3507fc93-313e-4a4c-8ca8-4d0ea0f97315)]
interface nsIScrollable : nsISupports
{
  /**
   * Constants declaring the two scroll orientations a scrollbar can be in.
   * ScrollOrientation_X - Horizontal scrolling.  When passing this
   *         in to a method you are requesting or setting data for the
   *         horizontal scrollbar.
   * ScrollOrientation_Y - Vertical scrolling.  When passing this
   *         in to a method you are requesting or setting data for the
   *         vertical scrollbar.
   */
  const long ScrollOrientation_X = 1;
  const long ScrollOrientation_Y = 2;

  /**
   * Constants declaring the states of the scrollbars.
   * ScrollPref_Auto - bars visible only when needed.
   * ScrollPref_Never - bars never visible, even when scrolling still possible.
   * ScrollPref_Always - bars always visible, even when scrolling is not possible
   */
  const long Scrollbar_Auto = 1;
  const long Scrollbar_Never = 2;
  const long Scrollbar_Always = 3;

  /**
   * Get or set the default scrollbar state for all documents in
   * this shell.
   */
  long getDefaultScrollbarPreferences(in long scrollOrientation);
  void setDefaultScrollbarPreferences(in long scrollOrientation,
                                      in long scrollbarPref);

  /**
   * Get information about whether the vertical and horizontal scrollbars are
   * currently visible.  If you are only interested in one of the visibility
   * settings pass nullptr in for the one you aren't interested in.
   */
  void getScrollbarVisibility(out boolean verticalVisible,
                              out boolean horizontalVisible);
};