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https://github.com/crystalidea/qt6windows7.git
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49 lines
1.8 KiB
C++
49 lines
1.8 KiB
C++
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// Copyright (C) 2016 The Qt Company Ltd.
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// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
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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)
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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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const auto touchPoints = touchEvent->points();
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if (touchPoints.count() == 2) {
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// determine scale factor
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const QEventPoint &touchPoint0 = touchPoints.first();
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const QEventPoint &touchPoint1 = touchPoints.last();
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qreal currentScaleFactor =
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QLineF(touchPoint0.position(), touchPoint1.position()).length()
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/ QLineF(touchPoint0.pressPosition(), touchPoint1.pressPosition()).length();
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if (touchEvent->touchPointStates() & QEventPoint::Released) {
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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::fromScale(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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