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120 lines
4.6 KiB
120 lines
4.6 KiB
/****************************************************************************
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**
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** Qt/Embedded Virtual Framebuffer
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**
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** Copyright (C) 1992-2008 Trolltech ASA. All rights reserved.
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**
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** This file is part of the Qt GUI Toolkit.
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**
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** This file may be used under the terms of the GNU General
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** Public License versions 2.0 or 3.0 as published by the Free
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** Software Foundation and appearing in the files LICENSE.GPL2
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** and LICENSE.GPL3 included in the packaging of this file.
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** Alternatively you may (at your option) use any later version
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** of the GNU General Public License if such license has been
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** publicly approved by Trolltech ASA (or its successors, if any)
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** and the KDE Free Qt Foundation.
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**
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** Please review the following information to ensure GNU General
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** Public Licensing requirements will be met:
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** http://trolltech.com/products/qt/licenses/licensing/opensource/.
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** If you are unsure which license is appropriate for your use, please
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** review the following information:
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** http://trolltech.com/products/qt/licenses/licensing/licensingoverview
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** or contact the sales department at sales@trolltech.com.
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**
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** This file may be used under the terms of the Q Public License as
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** defined by Trolltech ASA and appearing in the file LICENSE.QPL
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** included in the packaging of this file. Licensees holding valid Qt
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** Commercial licenses may use this file in accordance with the Qt
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** Commercial License Agreement provided with the Software.
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**
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** This file is provided "AS IS" with NO WARRANTY OF ANY KIND,
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** INCLUDING THE WARRANTIES OF DESIGN, MERCHANTABILITY AND FITNESS FOR
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** A PARTICULAR PURPOSE. Trolltech reserves all rights not granted
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** herein.
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**
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**********************************************************************/
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/*! \page emb-qvfb.html
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\title Qt/Embedded Virtual Framebuffer
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The virtual framebuffer allows Qt/Embedded programs to be developed on
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a desktop machine, without switching between consoles and X11.
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The virtual framebuffer is located in \c $QTDIR/tools/qvfb.
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\section1 Using the Virtual Framebuffer
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\list 1
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\i Configure Qt/Embedded with the \c -qvfb argument and compile the library:
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\code
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./configure -qvfb
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make
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\endcode
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\i Compile \c qvfb as a normal Qt/X11 application and run it. Do \e not
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compile it as a Qt/Embedded application.
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\i Start a Qt/Embedded master application (i.e., construct
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QApplication with the QApplication::GuiServer flag or use the \c
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-qws command line parameter). You can specify to the server that
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you wish to use the virtual framebuffer driver, e.g.:
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\code
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masterapp -qws -display QVFb:0
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\endcode
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\i Qt/Embedded will autodetect qvfb, so you can omit the \c -display
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command line parameter if you know that qvfb is running, and that
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the Qt/Embedded library supports qvfb. (If this is not the case,
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Qt/Embedded will write to the real framebuffer, and your X11
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display will be corrupted.)
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\endlist
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\c qvfb supports the following command line options:
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\table
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\header \i Option \i Meaning
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\row
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\i \c -width \e width
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\i the width of the virtual framebuffer (default: 240).
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\row
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\i \c -height \e height
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\i the height of the virtual framebuffer (default: 320).
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\row
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\i \c -depth \e depth
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\i the depth of the virtual framebuffer (1, 8 or 32; default: 8).
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\row
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\i \c -nocursor
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\i do not display the X11 cursor in the framebuffer window.
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\row
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\i \c -qwsdisplay \e :id
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\i the Qt/Embedded display id to provide (default: :0).
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\endtable
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\section1 Virtual Framebuffer Design
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The virtual framebuffer emulates a framebuffer using a shared memory region
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(the virtual frame buffer) and a utility to display the framebuffer in a
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window (\c qvfb). The regions of the display that have changed are updated
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periodically, so you will see discrete snapshots of the framebuffer rather
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than each individual drawing operation. For this reason drawing problems
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such as flickering may not be apparent until the program is run using a real
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framebuffer.
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The target refresh rate can be set via the <b>View|Refresh Rate</b>
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menu item. This will cause \c qvfb to check for updated regions more
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frequently. The rate is a target only. If little drawing is being
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done, the framebuffer will not show any updates between drawing
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events. If an application is displaying an animation the updates will
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be frequent, then the application and \c qvfb will compete for
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processor time.
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Mouse and keyboard events are passed to the Qt/Embedded master process via
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named pipes.
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The virtual framebuffer is a development tool only. No security issues have
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been considered in the virtual framebuffer design. It should be avoided
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in a production environment; do not configure production libraries with \c -qvfb.
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*/
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