| 1 | /****************************************************************************
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| 2 | **
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| 3 | ** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
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| 4 | ** All rights reserved.
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| 5 | ** Contact: Nokia Corporation (qt-info@nokia.com)
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| 6 | **
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| 7 | ** This file is part of the documentation of the Qt Toolkit.
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| 8 | **
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| 9 | ** $QT_BEGIN_LICENSE:FDL$
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| 10 | ** Commercial Usage
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| 11 | ** Licensees holding valid Qt Commercial licenses may use this file in
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| 12 | ** accordance with the Qt Commercial License Agreement provided with the
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| 13 | ** Software or, alternatively, in accordance with the terms contained in a
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| 14 | ** written agreement between you and Nokia.
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| 15 | **
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| 16 | ** GNU Free Documentation License
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| 17 | ** Alternatively, this file may be used under the terms of the GNU Free
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| 18 | ** Documentation License version 1.3 as published by the Free Software
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| 19 | ** Foundation and appearing in the file included in the packaging of this
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| 20 | ** file.
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| 21 | **
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| 22 | ** If you have questions regarding the use of this file, please contact
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| 23 | ** Nokia at qt-info@nokia.com.
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| 24 | ** $QT_END_LICENSE$
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| 25 | **
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| 26 | ****************************************************************************/
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| 27 |
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| 28 | /*!
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| 29 | \page restoring-geometry.html
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| 30 | \title Restoring a Window's Geometry
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| 31 | \brief How to save & restore window geometry.
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| 32 | \ingroup best-practices
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| 33 |
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| 34 | This document describes how to save and restore a \l{Window
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| 35 | Geometry}{window's geometry} using the geometry properties. On
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| 36 | Windows, this is basically storing the result of
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| 37 | QWidget::geometry() and calling QWidget::setGeometry() in the next
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| 38 | session before calling \l{QWidget::show()}{show()}.
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| 39 |
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| 40 | On X11, this might not work because an invisible window does not
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| 41 | have a frame yet. The window manager will decorate the window
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| 42 | later. When this happens, the window shifts towards the
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| 43 | bottom/right corner of the screen depending on the size of the
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| 44 | decoration frame. Although X provides a way to avoid this shift,
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| 45 | some window managers fail to implement this feature.
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| 46 |
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| 47 | Since version 4.2, Qt provides functions that saves and restores a
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| 48 | window's geometry and state for you. QWidget::saveGeometry()
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| 49 | saves the window geometry and maximized/fullscreen state, while
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| 50 | QWidget::restoreGeometry() restores it. The restore function also
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| 51 | checks if the restored geometry is outside the available screen
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| 52 | geometry, and modifies it as appropriate if it is:
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| 53 |
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| 54 | \snippet doc/src/snippets/code/src_gui_widgets_qmainwindow.cpp 0
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| 55 | \snippet doc/src/snippets/code/src_gui_widgets_qmainwindow.cpp 1
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| 56 |
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| 57 | If those functions are not available or cannot be used, then a
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| 58 | workaround is to call \l{QWidget::setGeometry()}{setGeometry()}
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| 59 | after \l{QWidget::show()}{show()}. This has the two disadvantages
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| 60 | that the widget appears at a wrong place for a millisecond
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| 61 | (results in flashing) and that currently only every second window
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| 62 | manager gets it right. A safer solution is to store both
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| 63 | \l{QWidget::pos()}{pos()} and \l{QWidget::size()}{size()} and to
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| 64 | restore the geometry using \l{QWidget::resize()} and
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| 65 | \l{QWidget::move()}{move()} before calling
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| 66 | \l{QWidget::show()}{show()}, as demonstrated in the
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| 67 | \l{mainwindows/application}{Application} example.
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| 68 | */
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