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+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the examples of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** BSD License Usage
+** Alternatively, you may use this file under the terms of the BSD license
+** as follows:
+**
+** "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 The Qt Company Ltd 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."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#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());
+
+ setTransform(QTransform().rotate(line2.angleTo(line1)), true);
+ }
+
+ break;
+ }
+
+ default:
+ return QGraphicsItem::sceneEvent(event);
+ }
+
+ return true;
+}