Method wheelEvent

app/src/UI/Widgets/GPS.cpp:1131–1179

* @brief Handles mouse wheel zooming. */

 * @brief Handles mouse wheel zooming.
 */
void Widgets::GPS::wheelEvent(QWheelEvent* event)
{
  const int delta = event->angleDelta().y();
  if (delta == 0)
    return;

  event->accept();

  const bool isTouchpad =
    !event->pixelDelta().isNull() || event->source() == Qt::MouseEventSynthesizedBySystem;

  double newZoom;
  if (isTouchpad) {
    const double zoomFactor = 1.05;
    const double deltaNorm  = -delta * kInv120;
    const double factor     = qPow(zoomFactor, -deltaNorm);
    newZoom                 = m_zoom * factor;
  } else {
    const double zoomStep = 0.5;
    newZoom               = m_zoom + (delta > 0 ? zoomStep : -zoomStep);
  }

  newZoom =
    qBound(static_cast<double>(MIN_ZOOM), newZoom, static_cast<double>(m_mapMaxZoom[m_mapType]));

  if (qAbs(newZoom - m_zoom) < 0.001)
    return;

  if (!autoCenter()) {
    const QPointF cursorPos = event->position();
    const QPointF cursorTileOffset((cursorPos.x() - width() * 0.5) * kInvTile,
                                   (cursorPos.y() - height() * 0.5) * kInvTile);

    const QPointF cursorTile = m_centerTile + cursorTileOffset;
    const QPointF geo        = tileToLatLon(cursorTile, m_zoom);
    m_zoom                   = newZoom;

    const QPointF newTile = latLonToTile(geo.x(), geo.y(), m_zoom);
    m_centerTile          = clampCenterTile(newTile - cursorTileOffset);

    updateTiles();
    update();

    Q_EMIT zoomLevelChanged();
  }

  else
    setZoomLevelPrecise(newZoom);
}

/**
 * @brief Handles map dragging via mouse move.