86 lines
3.7 KiB
C++
86 lines
3.7 KiB
C++
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/****************************************************************************
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**
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** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
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** All rights reserved.
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** Contact: Nokia Corporation (qt-info@nokia.com)
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**
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** This file is part of the examples of the Qt Toolkit.
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**
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** $QT_BEGIN_LICENSE:BSD$
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** You may use this file under the terms of the BSD license as follows:
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**
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** "Redistribution and use in source and binary forms, with or without
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** modification, are permitted provided that the following conditions are
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** met:
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** * Redistributions of source code must retain the above copyright
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** notice, this list of conditions and the following disclaimer.
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** * Redistributions in binary form must reproduce the above copyright
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** notice, this list of conditions and the following disclaimer in
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** the documentation and/or other materials provided with the
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** distribution.
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** * Neither the name of Nokia Corporation and its Subsidiary(-ies) nor
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** the names of its contributors may be used to endorse or promote
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** products derived from this software without specific prior written
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** permission.
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**
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** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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#include "graphicsview.h"
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#include <QScrollBar>
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#include <QTouchEvent>
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GraphicsView::GraphicsView(QGraphicsScene *scene, QWidget *parent)
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: QGraphicsView(scene, parent), totalScaleFactor(1)
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{
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viewport()->setAttribute(Qt::WA_AcceptTouchEvents);
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setDragMode(ScrollHandDrag);
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}
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bool GraphicsView::viewportEvent(QEvent *event)
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{
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switch (event->type()) {
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case QEvent::TouchBegin:
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case QEvent::TouchUpdate:
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case QEvent::TouchEnd:
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{
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QTouchEvent *touchEvent = static_cast<QTouchEvent *>(event);
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QList<QTouchEvent::TouchPoint> touchPoints = touchEvent->touchPoints();
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if (touchPoints.count() == 2) {
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// determine scale factor
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const QTouchEvent::TouchPoint &touchPoint0 = touchPoints.first();
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const QTouchEvent::TouchPoint &touchPoint1 = touchPoints.last();
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qreal currentScaleFactor =
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QLineF(touchPoint0.pos(), touchPoint1.pos()).length()
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/ QLineF(touchPoint0.startPos(), touchPoint1.startPos()).length();
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if (touchEvent->touchPointStates() & Qt::TouchPointReleased) {
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// if one of the fingers is released, remember the current scale
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// factor so that adding another finger later will continue zooming
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// by adding new scale factor to the existing remembered value.
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totalScaleFactor *= currentScaleFactor;
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currentScaleFactor = 1;
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}
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setTransform(QTransform().scale(totalScaleFactor * currentScaleFactor,
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totalScaleFactor * currentScaleFactor));
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}
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return true;
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}
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default:
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break;
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}
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return QGraphicsView::viewportEvent(event);
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}
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