LimeReport/limereport/lrgraphicsviewzoom.cpp

#include "lrgraphicsviewzoom.h"

#include <QApplication>
#include <QMouseEvent>
#include <qmath.h>

namespace LimeReport {

GraphicsViewZoomer::GraphicsViewZoomer(QGraphicsView* view): QObject(view), m_view(view)
{
    m_view->viewport()->installEventFilter(this);
    m_view->setMouseTracking(true);
    m_modifiers = Qt::ControlModifier;
    m_zoomFactorBase = 1.0009;
}

void GraphicsViewZoomer::gentleZoom(double factor)
{
    m_view->scale(factor, factor);
    m_view->centerOn(m_targetScenePos);
    QPointF delta_viewport_pos = m_targetViewportPos
        - QPointF(m_view->viewport()->width() / 2.0, m_view->viewport()->height() / 2.0);
    QPointF viewport_center = m_view->mapFromScene(m_targetScenePos) - delta_viewport_pos;
    m_view->centerOn(m_view->mapToScene(viewport_center.toPoint()));
    emit zoomed(factor);
}

void GraphicsViewZoomer::setModifiers(Qt::KeyboardModifiers modifiers) { m_modifiers = modifiers; }

void GraphicsViewZoomer::setZoomFactorBase(double value) { m_zoomFactorBase = value; }

void GraphicsViewZoomer::setView(QGraphicsView* view)
{
    if (m_view != view) {
        m_view->viewport()->removeEventFilter(this);
        m_view = view;
        m_view->viewport()->installEventFilter(this);
        m_view->setMouseTracking(true);
    }
}

bool GraphicsViewZoomer::eventFilter(QObject* object, QEvent* event)
{
    if (event->type() == QEvent::MouseMove) {
        QMouseEvent* mouse_event = static_cast<QMouseEvent*>(event);
        QPointF delta = m_targetViewportPos - mouse_event->pos();
        if (qAbs(delta.x()) > 5 || qAbs(delta.y()) > 5) {
            m_targetViewportPos = mouse_event->pos();
            m_targetScenePos = m_view->mapToScene(mouse_event->pos());
        }
    } else if (event->type() == QEvent::Wheel) {
        QWheelEvent* wheel_event = static_cast<QWheelEvent*>(event);
        if (QApplication::keyboardModifiers() == m_modifiers) {
#if (QT_VERSION < QT_VERSION_CHECK(5, 15, 1))
            if (wheel_event->orientation() == Qt::Vertical) {
                double angle = wheel_event->delta();
                double factor = qPow(m_zoomFactorBase, angle);
                gentleZoom(factor);
                return true;
            }
#else
            if (wheel_event->angleDelta().y() != 0) {
                double angle = wheel_event->angleDelta().y();
                double factor = qPow(m_zoomFactorBase, angle);
                gentleZoom(factor);
                return true;
            }
#endif
        }
    }
    Q_UNUSED(object)
    return false;
}

} // namespace LimeReport