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			104 lines
		
	
	
		
			4.0 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			104 lines
		
	
	
		
			4.0 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
///////////////////////////////////////////////////////////////////////////////////
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// Copyright (C) 2021-2022 Jon Beniston, M7RCE <jon@beniston.com>                //
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// Copyright (C) 2022 Jiří Pinkava <jiri.pinkava@rossum.ai>                      //
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//                                                                               //
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// This program is free software; you can redistribute it and/or modify          //
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// it under the terms of the GNU General Public License as published by          //
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// the Free Software Foundation as version 3 of the License, or                  //
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// (at your option) any later version.                                           //
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//                                                                               //
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// This program is distributed in the hope that it will be useful,               //
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// but WITHOUT ANY WARRANTY; without even the implied warranty of                //
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the                  //
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// GNU General Public License V3 for more details.                               //
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//                                                                               //
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// You should have received a copy of the GNU General Public License             //
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// along with this program. If not, see <http://www.gnu.org/licenses/>.          //
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///////////////////////////////////////////////////////////////////////////////////
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#include <QMouseEvent>
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#include <QApplication>
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#include <QScrollBar>
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#include <QGestureEvent>
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#include <QPinchGesture>
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#include <qmath.h>
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#include "graphicsviewzoom.h"
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GraphicsViewZoom::GraphicsViewZoom(QGraphicsView* view) :
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    QObject(view),
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    m_view(view),
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    m_modifiers(Qt::NoModifier),
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    m_zoomFactorBase(1.0015)
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{
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    m_view->viewport()->installEventFilter(this);
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    m_view->setMouseTracking(true);
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    m_view->viewport()->grabGesture(Qt::PinchGesture);
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}
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void GraphicsViewZoom::gentleZoom(double factor)
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{
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    m_view->scale(factor, factor);
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    m_view->centerOn(m_targetScenePos);
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    QPointF deltaViewportPos = m_targetViewportPos - QPointF(m_view->viewport()->width() / 2.0,
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                                                             m_view->viewport()->height() / 2.0);
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    QPointF viewportCenter = m_view->mapFromScene(m_targetScenePos) - deltaViewportPos;
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    m_view->centerOn(m_view->mapToScene(viewportCenter.toPoint()));
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    emit zoomed();
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}
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void GraphicsViewZoom::setModifiers(Qt::KeyboardModifiers modifiers)
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{
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    m_modifiers = modifiers;
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}
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void GraphicsViewZoom::setZoomFactorBase(double value)
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{
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    m_zoomFactorBase = value;
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}
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bool GraphicsViewZoom::eventFilter(QObject *object, QEvent *event)
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{
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    if (event->type() == QEvent::MouseMove)
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    {
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        QMouseEvent* mouseEvent = static_cast<QMouseEvent*>(event);
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        QPointF delta = m_targetViewportPos - mouseEvent->pos();
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        if (qAbs(delta.x()) > 5 || qAbs(delta.y()) > 5)
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        {
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            m_targetViewportPos = mouseEvent->pos();
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            m_targetScenePos = m_view->mapToScene(mouseEvent->pos());
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        }
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    }
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    else if (event->type() == QEvent::Wheel)
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    {
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        QWheelEvent* wheelEvent = static_cast<QWheelEvent*>(event);
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        if (QApplication::keyboardModifiers() == m_modifiers)
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        {
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            if (wheelEvent->angleDelta().y() != 0)
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            {
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                double angle = wheelEvent->angleDelta().y();
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                double factor = qPow(m_zoomFactorBase, angle);
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                gentleZoom(factor);
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                return true;
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            }
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        }
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    }
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    else if (event->type() == QEvent::Gesture)
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    {
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        QGestureEvent *gestureEvent = static_cast<QGestureEvent *>(event);
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        if (QPinchGesture *pinchGesture = static_cast<QPinchGesture *>(gestureEvent->gesture(Qt::PinchGesture)))
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        {
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            if (pinchGesture->changeFlags() & QPinchGesture::ScaleFactorChanged)
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            {
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                m_view->scale(pinchGesture->scaleFactor(), pinchGesture->scaleFactor());
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                emit zoomed();
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            }
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            return true;
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        }
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    }
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    Q_UNUSED(object)
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    return false;
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}
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