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author | Timothy Pearson <kb9vqf@pearsoncomputing.net> | 2011-07-10 15:24:15 -0500 |
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committer | Timothy Pearson <kb9vqf@pearsoncomputing.net> | 2011-07-10 15:24:15 -0500 |
commit | bd0f3345a938b35ce6a12f6150373b0955b8dd12 (patch) | |
tree | 7a520322212d48ebcb9fbe1087e7fca28b76185c /doc/qvfb.doc | |
download | qt3-bd0f3345a938b35ce6a12f6150373b0955b8dd12.tar.gz qt3-bd0f3345a938b35ce6a12f6150373b0955b8dd12.zip |
Add Qt3 development HEAD version
Diffstat (limited to 'doc/qvfb.doc')
-rw-r--r-- | doc/qvfb.doc | 119 |
1 files changed, 119 insertions, 0 deletions
diff --git a/doc/qvfb.doc b/doc/qvfb.doc new file mode 100644 index 0000000..7bc1546 --- /dev/null +++ b/doc/qvfb.doc @@ -0,0 +1,119 @@ +/**************************************************************************** +** +** Qt/Embedded Virtual Framebuffer +** +** Copyright (C) 1992-2008 Trolltech ASA. All rights reserved. +** +** This file is part of the Qt GUI Toolkit. +** +** This file may be used under the terms of the GNU General +** Public License versions 2.0 or 3.0 as published by the Free +** Software Foundation and appearing in the files LICENSE.GPL2 +** and LICENSE.GPL3 included in the packaging of this file. +** Alternatively you may (at your option) use any later version +** of the GNU General Public License if such license has been +** publicly approved by Trolltech ASA (or its successors, if any) +** and the KDE Free Qt Foundation. +** +** Please review the following information to ensure GNU General +** Public Licensing requirements will be met: +** http://trolltech.com/products/qt/licenses/licensing/opensource/. +** If you are unsure which license is appropriate for your use, please +** review the following information: +** http://trolltech.com/products/qt/licenses/licensing/licensingoverview +** or contact the sales department at sales@trolltech.com. +** +** This file may be used under the terms of the Q Public License as +** defined by Trolltech ASA and appearing in the file LICENSE.QPL +** included in the packaging of this file. Licensees holding valid Qt +** Commercial licenses may use this file in accordance with the Qt +** Commercial License Agreement provided with the Software. +** +** This file is provided "AS IS" with NO WARRANTY OF ANY KIND, +** INCLUDING THE WARRANTIES OF DESIGN, MERCHANTABILITY AND FITNESS FOR +** A PARTICULAR PURPOSE. Trolltech reserves all rights not granted +** herein. +** +**********************************************************************/ + +/*! \page emb-qvfb.html + +\title Qt/Embedded Virtual Framebuffer + +The virtual framebuffer allows Qt/Embedded programs to be developed on +a desktop machine, without switching between consoles and X11. + +The virtual framebuffer is located in \c $QTDIR/tools/qvfb. + +\section1 Using the Virtual Framebuffer + +\list 1 +\i Configure Qt/Embedded with the \c -qvfb argument and compile the library: + \code + ./configure -qvfb + make + \endcode +\i Compile \c qvfb as a normal Qt/X11 application and run it. Do \e not + compile it as a Qt/Embedded application. +\i Start a Qt/Embedded master application (i.e., construct + QApplication with the QApplication::GuiServer flag or use the \c + -qws command line parameter). You can specify to the server that + you wish to use the virtual framebuffer driver, e.g.: + \code + masterapp -qws -display QVFb:0 + \endcode +\i Qt/Embedded will autodetect qvfb, so you can omit the \c -display + command line parameter if you know that qvfb is running, and that + the Qt/Embedded library supports qvfb. (If this is not the case, + Qt/Embedded will write to the real framebuffer, and your X11 + display will be corrupted.) + +\endlist + +\c qvfb supports the following command line options: + +\table +\header \i Option \i Meaning +\row +\i \c -width \e width +\i the width of the virtual framebuffer (default: 240). +\row +\i \c -height \e height +\i the height of the virtual framebuffer (default: 320). +\row +\i \c -depth \e depth +\i the depth of the virtual framebuffer (1, 8 or 32; default: 8). +\row +\i \c -nocursor +\i do not display the X11 cursor in the framebuffer window. +\row +\i \c -qwsdisplay \e :id +\i the Qt/Embedded display id to provide (default: :0). +\endtable + +\section1 Virtual Framebuffer Design + +The virtual framebuffer emulates a framebuffer using a shared memory region +(the virtual frame buffer) and a utility to display the framebuffer in a +window (\c qvfb). The regions of the display that have changed are updated +periodically, so you will see discrete snapshots of the framebuffer rather +than each individual drawing operation. For this reason drawing problems +such as flickering may not be apparent until the program is run using a real +framebuffer. + +The target refresh rate can be set via the <b>View|Refresh Rate</b> +menu item. This will cause \c qvfb to check for updated regions more +frequently. The rate is a target only. If little drawing is being +done, the framebuffer will not show any updates between drawing +events. If an application is displaying an animation the updates will +be frequent, then the application and \c qvfb will compete for +processor time. + +Mouse and keyboard events are passed to the Qt/Embedded master process via +named pipes. + +The virtual framebuffer is a development tool only. No security issues have +been considered in the virtual framebuffer design. It should be avoided +in a production environment; do not configure production libraries with \c -qvfb. + +*/ |