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Diffstat (limited to 'examples/widgets/touch/pinchzoom/graphicsview.cpp')
-rw-r--r-- | examples/widgets/touch/pinchzoom/graphicsview.cpp | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/examples/widgets/touch/pinchzoom/graphicsview.cpp b/examples/widgets/touch/pinchzoom/graphicsview.cpp new file mode 100644 index 0000000000..54e134aea2 --- /dev/null +++ b/examples/widgets/touch/pinchzoom/graphicsview.cpp @@ -0,0 +1,95 @@ +/**************************************************************************** +** +** 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 "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); +} |