- Qt 6.6
- Qt Graphs
- Graph Gallery
- Qt Graphs | Commercial or GPLv3

# Graph Gallery

     // Copyright (C) 2023 The Qt Company Ltd.
     // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause

     #include "custominputhandler.h"

     #include <QtGraphs/q3dcamera.h>
     #include <QtCore/qmath.h>

     CustomInputHandler::CustomInputHandler(QAbstract3DGraph *graph, QObject *parent) :
         Q3DInputHandler(parent)
     {
         // Connect to the item selection signal from graph
         connect(graph, &QAbstract3DGraph::selectedElementChanged, this,
                 &CustomInputHandler::handleElementSelected);
     }

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

     void CustomInputHandler::wheelEvent(QWheelEvent *event)
     {
         float delta = float(event->angleDelta().y());

         m_axisXMinValue += delta;
         m_axisXMaxValue -= delta;
         m_axisZMinValue += delta;
         m_axisZMaxValue -= delta;
         checkConstraints();

         float y = (m_axisXMaxValue - m_axisXMinValue) * m_aspectRatio;

         m_axisX->setRange(m_axisXMinValue, m_axisXMaxValue);
         m_axisY->setRange(100.f, y);
         m_axisZ->setRange(m_axisZMinValue, m_axisZMaxValue);
     }

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

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

     void CustomInputHandler::handleAxisDragging()
     {
         float distance = 0.f;

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

         // 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();

         // Adjust axes
         switch (m_state) {
         case StateDraggingX:
             distance = (move.x() * xMulX - move.y() * xMulY) * m_speedModifier;
             m_axisXMinValue -= distance;
             m_axisXMaxValue -= distance;
             if (m_axisXMinValue < m_areaMinValue) {
                 float dist = m_axisXMaxValue - m_axisXMinValue;
                 m_axisXMinValue = m_areaMinValue;
                 m_axisXMaxValue = m_axisXMinValue + dist;
             }
             if (m_axisXMaxValue > m_areaMaxValue) {
                 float dist = m_axisXMaxValue - m_axisXMinValue;
                 m_axisXMaxValue = m_areaMaxValue;
                 m_axisXMinValue = m_axisXMaxValue - dist;
             }
             m_axisX->setRange(m_axisXMinValue, m_axisXMaxValue);
             break;
         case StateDraggingZ:
             distance = (move.x() * zMulX + move.y() * zMulY) * m_speedModifier;
             m_axisZMinValue += distance;
             m_axisZMaxValue += distance;
             if (m_axisZMinValue < m_areaMinValue) {
                 float dist = m_axisZMaxValue - m_axisZMinValue;
                 m_axisZMinValue = m_areaMinValue;
                 m_axisZMaxValue = m_axisZMinValue + dist;
             }
             if (m_axisZMaxValue > m_areaMaxValue) {
                 float dist = m_axisZMaxValue - m_axisZMinValue;
                 m_axisZMaxValue = m_areaMaxValue;
                 m_axisZMinValue = m_axisZMaxValue - dist;
             }
             m_axisZ->setRange(m_axisZMinValue, m_axisZMaxValue);
             break;
         default:
             break;
         }
     }

     void CustomInputHandler::checkConstraints()
     {
         if (m_axisXMinValue < m_areaMinValue)
             m_axisXMinValue = m_areaMinValue;
         if (m_axisXMaxValue > m_areaMaxValue)
             m_axisXMaxValue = m_areaMaxValue;
         // Don't allow too much zoom in
         if ((m_axisXMaxValue - m_axisXMinValue) < m_axisXMinRange) {
             float adjust = (m_axisXMinRange - (m_axisXMaxValue - m_axisXMinValue)) / 2.f;
             m_axisXMinValue -= adjust;
             m_axisXMaxValue += adjust;
         }

         if (m_axisZMinValue < m_areaMinValue)
             m_axisZMinValue = m_areaMinValue;
         if (m_axisZMaxValue > m_areaMaxValue)
             m_axisZMaxValue = m_areaMaxValue;
         // Don't allow too much zoom in
         if ((m_axisZMaxValue - m_axisZMinValue) < m_axisZMinRange) {
             float adjust = (m_axisZMinRange - (m_axisZMaxValue - m_axisZMinValue)) / 2.f;
             m_axisZMinValue -= adjust;
             m_axisZMaxValue += adjust;
         }
     }