| 1 | /****************************************************************************
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| 2 | **
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| 3 | ** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
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| 4 | ** All rights reserved.
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| 5 | ** Contact: Nokia Corporation ([email protected])
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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 | ** $QT_BEGIN_LICENSE:LGPL$
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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
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| 14 | ** a written agreement between you and Nokia.
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| 15 | **
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| 16 | ** GNU Lesser General Public License Usage
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| 17 | ** Alternatively, this file may be used under the terms of the GNU Lesser
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| 18 | ** General Public License version 2.1 as published by the Free Software
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| 19 | ** Foundation and appearing in the file LICENSE.LGPL included in the
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| 20 | ** packaging of this file. Please review the following information to
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| 21 | ** ensure the GNU Lesser General Public License version 2.1 requirements
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| 22 | ** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
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| 23 | **
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| 24 | ** In addition, as a special exception, Nokia gives you certain additional
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| 25 | ** rights. These rights are described in the Nokia Qt LGPL Exception
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| 26 | ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
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| 27 | **
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| 28 | ** GNU General Public License Usage
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| 29 | ** Alternatively, this file may be used under the terms of the GNU
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| 30 | ** General Public License version 3.0 as published by the Free Software
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| 31 | ** Foundation and appearing in the file LICENSE.GPL included in the
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| 32 | ** packaging of this file. Please review the following information to
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| 33 | ** ensure the GNU General Public License version 3.0 requirements will be
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| 34 | ** met: http://www.gnu.org/copyleft/gpl.html.
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| 35 | **
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| 36 | ** If you have questions regarding the use of this file, please contact
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| 37 | ** Nokia at [email protected].
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| 38 | ** $QT_END_LICENSE$
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| 39 | **
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| 40 | ****************************************************************************/
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| 41 |
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| 42 | /*!
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| 43 | \page x11overlays.html
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| 44 | \title How to Use X11 Overlays with Qt
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| 45 |
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| 46 | X11 overlays are a powerful mechanism for drawing
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| 47 | annotations etc., on top of an image without destroying it, thus saving
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| 48 | a great deal of image rendering time. For more information, see the highly
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| 49 | recommended book \e{OpenGL Programming for the X Window System} (Mark
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| 50 | Kilgard, Addison Wesley Developers Press 1996).
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| 51 |
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| 52 | \warning The Qt OpenGL Extension includes direct support for the
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| 53 | use of OpenGL overlays. For many uses of overlays, this makes the
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| 54 | technique described below redundant. The following is a discussion
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| 55 | on how to use non-QGL widgets in overlay planes.
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| 56 |
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| 57 | In the typical case, X11 overlays can easily be used together with the
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| 58 | current version of Qt and the Qt OpenGL Extension. The following
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| 59 | requirements apply:
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| 60 |
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| 61 | \list 1
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| 62 | \i Your X server and graphics card/hardware must support overlays.
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| 63 | For many X servers, overlay support can be turned on with
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| 64 | a configuration option; consult your X server installation
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| 65 | documentation.
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| 66 |
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| 67 | \i Your X server must (be configured to) use an overlay visual as the
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