Просмотр исходного текста страницы C++/Qt/QEvent

==Extend QObject to create keyboard filter==


   
<source lang="cpp">  
Foundations of Qt Development\Chapter06\eventfilter\main.cpp
/*
 * Copyright (c) 2006-2007, Johan Thelin
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 * 
 *     * Redistributions of source code must retain the above copyright notice, 
 *       this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright notice,  
 *       this list of conditions and the following disclaimer in the documentation 
 *       and/or other materials provided with the distribution.
 *     * Neither the name of APress nor the names of its contributors 
 *       may be used to endorse or promote products derived from this software 
 *       without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
#include <QApplication>
#include <QLineEdit>
#include <QKeyEvent>
class KeyboardFilter : public QObject
{
public:
  KeyboardFilter( QObject *parent = 0 ) : QObject( parent ) {}
  
protected:
  bool eventFilter( QObject *dist, QEvent *event )
  {
    if( event->type() == QEvent::KeyPress )
    {
      QKeyEvent *keyEvent = static_cast<QKeyEvent*>( event );
      if( QString("1234567890").indexOf( keyEvent->text() ) != -1 )
        return true;
    }
    return false;
  }
};
int main( int argc, char **argv )
{
  QApplication app( argc, argv );
  
  QLineEdit lineEdit;
  KeyboardFilter filter;
  
  lineEdit.installEventFilter( &filter );
  lineEdit.show();
  
  return app.exec();
}
   
    
  </source>


==Subclass QEvent==


   
<source lang="cpp">  
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights.  These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/
#include <QCheckBox>
#include <QMouseEvent>
class MyCheckBox : public QCheckBox
{
public:
    void mousePressEvent(QMouseEvent *event);
};
void MyCheckBox::mousePressEvent(QMouseEvent *event)
{
    if (event->button() == Qt::LeftButton) {
        // handle left mouse button here
    } else {
        // pass on other buttons to base class
        QCheckBox::mousePressEvent(event);
    }
}
class MyWidget : public QWidget
{
public:
    bool event(QEvent *event);
};
static const int MyCustomEventType = 1099;
class MyCustomEvent : public QEvent
{
public:
    MyCustomEvent() : QEvent((QEvent::Type)MyCustomEventType) {}
};
bool MyWidget::event(QEvent *event)
{
    if (event->type() == QEvent::KeyPress) {
     QKeyEvent *ke = static_cast<QKeyEvent *>(event);
     if (ke->key() == Qt::Key_Tab) {
        return true;
     }
    } else if (event->type() == MyCustomEventType) {
     MyCustomEvent *myEvent = static_cast<MyCustomEvent *>(event);
       return true;
    }
    return QWidget::event(event);
}
int main()
{
}
   
    
  </source>