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/****************************************************************************
**
** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** 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 Digia. For licensing terms and
** conditions see http://qt.digia.com/licensing. For further information
** use the contact form at http://qt.digia.com/contact-us.
**
** 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, Digia gives you certain additional
** rights. These rights are described in the Digia 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.
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
#include "graphicsview.h"
#include <QScrollBar>
#include <QTouchEvent>
GraphicsView::GraphicsView(QGraphicsScene *scene, QWidget *parent)
: QGraphicsView(scene, parent), totalScaleFactor(1)
{
viewport()->setAttribute(Qt::WA_AcceptTouchEvents);
setDragMode(ScrollHandDrag);
}
bool GraphicsView::viewportEvent(QEvent *event)
{
switch (event->type()) {
case QEvent::TouchBegin:
case QEvent::TouchUpdate:
case QEvent::TouchEnd:
{
QTouchEvent *touchEvent = static_cast<QTouchEvent *>(event);
QList<QTouchEvent::TouchPoint> touchPoints = touchEvent->touchPoints();
if (touchPoints.count() == 2) {
// determine scale factor
const QTouchEvent::TouchPoint &touchPoint0 = touchPoints.first();
const QTouchEvent::TouchPoint &touchPoint1 = touchPoints.last();
qreal currentScaleFactor =
QLineF(touchPoint0.pos(), touchPoint1.pos()).length()
/ QLineF(touchPoint0.startPos(), touchPoint1.startPos()).length();
if (touchEvent->touchPointStates() & Qt::TouchPointReleased) {
// if one of the fingers is released, remember the current scale
// factor so that adding another finger later will continue zooming
// by adding new scale factor to the existing remembered value.
totalScaleFactor *= currentScaleFactor;
currentScaleFactor = 1;
}
setTransform(QTransform().scale(totalScaleFactor * currentScaleFactor,
totalScaleFactor * currentScaleFactor));
}
return true;
}
default:
break;
}
return QGraphicsView::viewportEvent(event);
}
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