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diff --git a/doc/src/howtos/restoring-geometry.qdoc b/doc/src/howtos/restoring-geometry.qdoc new file mode 100644 index 0000000..c9e6f4f --- /dev/null +++ b/doc/src/howtos/restoring-geometry.qdoc @@ -0,0 +1,87 @@ +/**************************************************************************** +** +** 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. +*/ |