{

// Mouse is over the widget, so grab focus (for keyboard events)

setFocus();

// Check previous position

if (lastMousePosition_.isNull())

{

lastMousePosition_ = QPoint(event->x(), event->y());

return;

}

// Right button - Rotate scene volume (3D)

if (event->buttons() & Qt3DInput::QMouseEvent::RightButton)

{

// Rotations only allowed for 3D view

if (!flatView_)

{

viewRotationMatrix_ *=

QQuaternion::fromEulerAngles(event->y() - lastMousePosition_.y(), event->x() - lastMousePosition_.x(), 0.0);

sceneRootTransform_->setRotation(viewRotationMatrix_);

}

}

// Middle button - translate axis ranges (2D)

if (event->buttons() & Qt3DInput::QMouseEvent::MiddleButton)

{

if (flatView_)

{

xAxis_->shiftLimitsByPixels(lastMousePosition_.x() - event->x());

yAxis_->shiftLimitsByPixels(event->y() - lastMousePosition_.y());

updateTransforms();

}

}

lastMousePosition_ = QPoint(event->x(), event->y());

if (flatView_)

{

// Ensure that mouse is within plot area.

if ((event->x() >= metrics_.displayVolumeOrigin().x()) &&

(event->x() <= (metrics_.displayVolumeExtent().x() + metrics_.displayVolumeOrigin().x())) &&

(height() - event->y() >= metrics_.displayVolumeOrigin().y()) &&

(height() - event->y() <= (metrics_.displayVolumeExtent().y() + metrics_.displayVolumeOrigin().y())))

{

// Convert mouse position to 2D axes value.

auto coords = toAxes2D(QPoint(event->x(), height() - event->y()));

// Emit signal indicating that mouse coordinates have been changed.

emit mouseCoordChanged(coords);

// Update the mouse coordinates in the text entity.

mouseCoordEntity_->setText(QString("%1 %2").arg(coords.x(), 0, 'g', 4).arg(coords.y(), 0, 'g', 4));

// Enable the text entity, to ensure that it is visible.

mouseCoordEntity_->setEnabled(true);

if (mouseCoordStyle_ == CoordinateDisplayStyle::FixedAnchor)

{

// Anchor the text entity at the bottom left of the widget.

mouseCoordEntity_->setAnchorPosition(

{-metrics_.displayVolumeOrigin().x(), -metrics_.displayVolumeOrigin().y(), 0.1});

}

else if (mouseCoordStyle_ == CoordinateDisplayStyle::MouseAnchor)

{

// Anchor the text entity at the mouse cursor.

mouseCoordEntity_->setAnchorPosition({float(event->x()) - metrics_.displayVolumeOrigin().x(),

height() - float(event->y()) - metrics_.displayVolumeOrigin().y(), 0});

}

else if (mouseCoordStyle_ == CoordinateDisplayStyle::None)

{

// Hide the text entity.

mouseCoordEntity_->setEnabled(false);

}

}

else

{

// Hide the text entity.

mouseCoordEntity_->setEnabled(false);

}

}

updateShaderParameters();

{

if (flatView_)

{

const auto sensitivity = 3;

// Determine factor based on wheel amount, and axis deltas based on that

auto sign = event->angleDelta().y() > 0 ? 1 : -1;

const auto factor = 0.05;

auto xDelta = xAxis_->range() * factor * sign;

auto yDelta = yAxis_->range() * factor * sign;

xAxis_->setLimits(xAxis_->minimum() + xDelta, xAxis_->maximum() - xDelta);

yAxis_->setLimits(yAxis_->minimum() + yDelta, yAxis_->maximum() - yDelta);

// Shift view centre towards current mouse position

// -- Get the data-space delta between the centre coordinates of the 2D axes and the current mouse position

auto centreDelta = QPoint(event->x(), height() - event->y()) - screen2DCentre();

xAxis_->shiftLimitsByPixels(centreDelta.x() / (sign * sensitivity));

yAxis_->shiftLimitsByPixels(centreDelta.y() / (sign * sensitivity));

updateTransforms();

}