/* -*- Mode: IDL; tab-width: 4; 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.  It simply deals blindly with scroll
 * position as a composite of the lowest possible scroll position, the highest
 * possible position and the current position lying somewhere between the 
 * min and the max.
 *
 * XXXroc in our tree, only get/setDefaultScrollbarPreferences and
 * getScrollbarVisibility are actually used externally. We should gut
 * the rest. nsDocShell is using twips for all these coordinates
 * which is going to confuse people anyway...
 */

[scriptable, uuid(919e792a-6490-40b8-bba5-f9e9ad5640c8)]
interface nsIScrollable : nsISupports
{
	/*
	Constants declaring the two scroll orientations a scroll bar can be in.
        ScrollOrientation_X - Horizontal scrolling.  When passing this
                in to a scroll position method you are requesting or
                setting the positions for the horizontal scroll bar.
        ScrollOrientation_Y - Vertical scrolling.  When passing this
                in to a scroll position you are requesting or setting
                the positions for the vertical scroll bar.
	*/
	const long ScrollOrientation_X = 1;
	const long ScrollOrientation_Y = 2;

	/*
	Retrieves or Sets the current thumb position to the curPos passed in for the
	scrolling orientation passed in.  curPos should be between minPos and maxPos.

	@return	NS_OK - Setting or Getting completed successfully.
				NS_ERROR_INVALID_ARG - returned when curPos is not within the
					minPos and maxPos.
	*/
	long getCurScrollPos(in long scrollOrientation);
	void setCurScrollPos(in long scrollOrientation, in long curPos);

	/*
	This function atomizes the ability to scroll in two dimensions at the same
	time.
	*/
	void setCurScrollPosEx(in long curHorizontalPos, in long curVerticalPos);

	/*
	Retrieves or Sets the valid ranges for the thumb.  When maxPos is set to 
	something less than the current thumb position, curPos is set = to maxPos.

	@return	NS_OK - Setting or Getting completed successfully.
				NS_ERROR_INVALID_ARG - returned when curPos is not within the
					minPos and maxPos.
	*/
	void getScrollRange(in long scrollOrientation, out long minPos, out long maxPos);
	void setScrollRange(in long scrollOrientation, in long minPos, in long maxPos);

	/*
	This function atomizes the ability to set the ranges in two dimensions at 
	the same time.
	*/
	void setScrollRangeEx(in long minHorizontalPos, in long maxHorizontalPos,
		in long minVerticalPos, in long maxVerticalPos);

	/*
	Constants declaring the states of the scroll bars.
	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;

	/*
	Retrieves or Set the preferences for the scroll bar.
	current is 'scrolling preference for this document'
	default is 'scrolling preference for all documents in this shell'
	resetScrollbarPreferences resets current to default
	*/
	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.  nsnull is a valid argument.  If you are only interested
	in one of the visibility settings pass nsnull in for the one you aren't
	interested in.
	*/
	void getScrollbarVisibility(out boolean verticalVisible, 
		out boolean horizontalVisible);
};
