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/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the either Technology Preview License Agreement or the
** Beta Release License Agreement.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain
** additional rights. These rights are described in the Nokia Qt LGPL
** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
** package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you are unsure which license is appropriate for your use, please
** contact the sales department at http://qt.nokia.com/contact.
** $QT_END_LICENSE$
**
****************************************************************************/
/*!
\page restoring-geometry.html
\title Restoring a Window's Geometry
\ingroup best-practices
This document describes how to save and restore a window's
geometry using the geometry properties. On Windows, this is
basically storing the result of QWidget::geometry() and calling
QWidget::setGeometry() in the next session before calling
\l{QWidget::show()}{show()}.
On X11, this won't work because an invisible window doesn't have
a frame yet. The window manager will decorate the window later.
When this happens, the window shifts towards the bottom/right
corner of the screen depending on the size of the decoration frame.
Although X provides a way to avoid this shift, most window managers
fail to implement this feature.
Since version 4.2, Qt provides functions that saves and restores a
window's geometry and state for you. QWidget::saveGeometry()
saves the window geometry and maximized/fullscreen state, while
QWidget::restoreGeometry() restores it. The restore function also
checks if the restored geometry is outside the available screen
geometry, and modifies it as appropriate if it is.
If those functions are not available or cannot be used, then a
workaround is to call \l{QWidget::setGeometry()}{setGeometry()}
after \l{QWidget::show()}{show()}. This has the two disadvantages
that the widget appears at a wrong place for a millisecond
(results in flashing) and that currently only every second window
manager gets it right. A safer solution is to store both
\l{QWidget::pos()}{pos()} and \l{QWidget::size()}{size()} and to
restore the geometry using \l{QWidget::resize()} and
\l{QWidget::move()}{move()} before calling
\l{QWidget::show()}{show()}, as demonstrated in the following
code snippets (from the \l{mainwindows/application}{Application}
example):
\snippet examples/mainwindows/application/mainwindow.cpp 35
\codeline
\snippet examples/mainwindows/application/mainwindow.cpp 38
This method works on Windows, Mac OS X, and most X11 window
managers.
*/
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