Axis Range Dragging With Labels Example

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 #include "axesinputhandler.h"
 #include <QtCore/qmath.h>

 AxesInputHandler::AxesInputHandler(QAbstract3DGraph *graph, QObject *parent) :
     Q3DInputHandler(parent),
     m_mousePressed(false),
     m_state(StateNormal),
     m_axisX(0),
     m_axisZ(0),
     m_axisY(0),
     m_speedModifier(15.0f)
 {
     // Connect to the item selection signal from graph
     connect(graph, &QAbstract3DGraph::selectedElementChanged, this,
             &AxesInputHandler::handleElementSelected);
 }

 void AxesInputHandler::mousePressEvent(QMouseEvent *event, const QPoint &mousePos)
 {
     Q3DInputHandler::mousePressEvent(event, mousePos);
     if (Qt::LeftButton == event->button())
         m_mousePressed = true;
 }

 void AxesInputHandler::mouseMoveEvent(QMouseEvent *event, const QPoint &mousePos)
 {
     // Check if we're trying to drag axis label
     if (m_mousePressed && m_state != StateNormal) {
         setPreviousInputPos(inputPosition());
         setInputPosition(mousePos);
         handleAxisDragging();
     } else {
         Q3DInputHandler::mouseMoveEvent(event, mousePos);
     }
 }

 void AxesInputHandler::mouseReleaseEvent(QMouseEvent *event, const QPoint &mousePos)
 {
     Q3DInputHandler::mouseReleaseEvent(event, mousePos);
     m_mousePressed = false;
     m_state = StateNormal;
 }

 void AxesInputHandler::handleElementSelected(QAbstract3DGraph::ElementType type)
 {
     switch (type) {
     case QAbstract3DGraph::ElementAxisXLabel:
         m_state = StateDraggingX;
         break;
     case QAbstract3DGraph::ElementAxisYLabel:
         m_state = StateDraggingY;
         break;
     case QAbstract3DGraph::ElementAxisZLabel:
         m_state = StateDraggingZ;
         break;
     default:
         m_state = StateNormal;
         break;
     }
 }

 void AxesInputHandler::handleAxisDragging()
 {
     float distance = 0.0f;

     // Get scene orientation from active camera
     float xRotation = scene()->activeCamera()->xRotation();
     float yRotation = scene()->activeCamera()->yRotation();

     // Calculate directional drag multipliers based on rotation
     float xMulX = qCos(qDegreesToRadians(xRotation));
     float xMulY = qSin(qDegreesToRadians(xRotation));
     float zMulX = qSin(qDegreesToRadians(xRotation));
     float zMulY = qCos(qDegreesToRadians(xRotation));

     // Get the drag amount
     QPoint move = inputPosition() - previousInputPos();

     // Flip the effect of y movement if we're viewing from below
     float yMove = (yRotation < 0) ? -move.y() : move.y();

     // Adjust axes
     switch (m_state) {
     case StateDraggingX:
         distance = (move.x() * xMulX - yMove * xMulY) / m_speedModifier;
         m_axisX->setRange(m_axisX->min() - distance, m_axisX->max() - distance);
         break;
     case StateDraggingZ:
         distance = (move.x() * zMulX + yMove * zMulY) / m_speedModifier;
         m_axisZ->setRange(m_axisZ->min() + distance, m_axisZ->max() + distance);
         break;
     case StateDraggingY:
         distance = move.y() / m_speedModifier; // No need to use adjusted y move here
         m_axisY->setRange(m_axisY->min() + distance, m_axisY->max() + distance);
         break;
     default:
         break;
     }
 }