|  | Home · All Classes · All Functions · Overviews

# knob.cpp Example File
multitouch/knobs/knob.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 examples 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 "knob.h"

     #include <QBrush>
     #include <QTouchEvent>

     Knob::Knob()
         : QGraphicsEllipseItem(-50, -50, 100, 100)
     {
         setAcceptTouchEvents(true);
         setBrush(Qt::lightGray);

         QGraphicsEllipseItem *leftItem = new QGraphicsEllipseItem(0, 0, 20, 20, this);
         leftItem->setPos(-40, -10);
         leftItem->setBrush(Qt::darkGreen);

         QGraphicsEllipseItem *rightItem = new QGraphicsEllipseItem(0, 0, 20, 20, this);
         rightItem->setPos(20, -10);
         rightItem->setBrush(Qt::darkRed);
     }

     bool Knob::sceneEvent(QEvent *event)
     {
         switch (event->type()) {
         case QEvent::TouchBegin:
         case QEvent::TouchUpdate:
         case QEvent::TouchEnd:
         {
             QTouchEvent *touchEvent = static_cast<QTouchEvent *>(event);

             if (touchEvent->touchPoints().count() == 2) {
                 const QTouchEvent::TouchPoint &touchPoint1 = touchEvent->touchPoints().first();
                 const QTouchEvent::TouchPoint &touchPoint2 = touchEvent->touchPoints().last();

                 QLineF line1(touchPoint1.lastScenePos(), touchPoint2.lastScenePos());
                 QLineF line2(touchPoint1.scenePos(), touchPoint2.scenePos());

                 rotate(line2.angleTo(line1));
             }

             break;
         }

         default:
             return QGraphicsItem::sceneEvent(event);
         }

         return true;
     }