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132 lines
5.1 KiB
132 lines
5.1 KiB
/****************************************************************************
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**
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** Documentation of character input
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**
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** Copyright (C) 2000-2008 Trolltech ASA. All rights reserved.
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**
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** This file is part of the TQt 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 TQt 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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/*!
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\page emb-charinput.html
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\title Character input in Qt/Embedded
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Internally in the client/server protocol, each key press and key
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release is sent as a \c{QWSKeyEvent}. A QWSKeyEvent contains the
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following fields:
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\table
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\row \i \c{unicode}
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\i Unicode value
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\row \i \c{keycode}
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\i TQt keycode value as defined in \c ntqnamespace.h
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\row \i \c{modifier}
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\i A bitfield consisting of some of \c TQt::ShiftButton,
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\c TQt::ControlButton, and \c TQt::AltButton.
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\row \i \c{is_press}
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\i TRUE if this is a key press, FALSE if it is a key release.
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\row \i \c{is_auto_repeat}
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\i TRUE if this event is caused by auto repeat.
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\endtable
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When the server receives a key event it is sent to each client process
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which is responsible for processing the key event and sending it to
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the right window, if any. Key events may come from several different
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sources.
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\section1 Keyboard drivers
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A keyboard driver reads data from a device and gives key events to the
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server.
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Keyboard drivers can be compiled into the library or loaded as
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plugins. Running ./configure -help lists the available keyboard drivers.
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The "tty" driver is enabled in the default configuration.
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The keyboard drivers all follow the same pattern. They read keyboard
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data from a device, find out which keys were pressed, and then call
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the static function QWSServer::processKeyEvent() with the key information.
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At present, the console keyboard driver also handles console switching
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(<b>Ctrl+Alt-F1</b>...<b>Ctrl+Alt+F10</b>) and termination
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(<b>Ctrl+Alt+Backspace</b>).
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To add a keyboard driver for a new device, subclasses of
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\c{QWSKeyboardHandler} and \c{QKbdDriverPlugin} can be
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written and installed as plugins.
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\section1 Key event filters (input methods)
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When the server receives a key event from a keyboard driver, it first
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passes it through a filter.
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This can be used to implement input methods, providing input of
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characters that are not on the keyboard.
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To make an input method, subclass QWSServer::KeyboardFilter (in \c
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src/kernel/qwindowsystem_qws.h) and implement the virtual function \c
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filter(). If \c filter() returns \c FALSE, the event will be sent to
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the clients (using QWSServer::sendKeyEvent()). If \c filter() returns
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\c TRUE, the event will be stopped. To generate new key events, use
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QWSServer::sendKeyEvent(). (Do not use processKeyEvent(), since this
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will lead to infinite recursion.)
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To install a keyboard event filter, use
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\c{QWSServer::setKeyboardFilter()}. Currently, only one filter
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can be installed at a time.
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Filtering must be done in the server process.
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The launcher example contains an example of a simple input method,
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\c{SimpleIM} which reads a substitution table from a file.
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\section1 Pen input
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Key events do not need to come from a keyboard device. The server
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process may call QWSServer::sendKeyEvent() at any time.
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Typically, this is done by popping up a widget, and letting the user
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specify characters with the pointer device.
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<b>Note</b>: the key input widget should not take focus, since the
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server would then just send the key events back to the input widget.
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One way to make sure that the input widget never takes focus is to set
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the \c{WStyle_Customize} and \c{WStyle_Tool} widget flags in
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the TQWidget constructor.
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The \link http://www.trolltech.com/products/qtopia/ Qtopia\endlink
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environment contains various input widgets such as
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Handwriting Recognition and Virtual Keyboard.
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*/
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