libQGLViewer keyboardAndMouse example

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# The keyboardAndMouse example

Shows how to customize your keyboard and mouse bindings.

Use `setShortcut()` to change standard action bindings (axis, grid or fps display, exit...).

Use `setMouseBinding()` and `setWheelBinding()` to change standard action mouse bindings (camera rotation, translation, object selection...).

If you want to define new keyboard shortcuts, overload `keyPressEvent()` and bind your own new actions. Use setKeyDescription() to add your shortcuts in the help window.

To define new mouse actions, overload `mouse(Press|Move|Release)Event`. See the `mouseMoveEvent()` documentation for an example. Overload `setMouseBindingDescription()` to update the help window binding tab.

## keyboardAndMouse.h

    #include <QGLViewer/qglviewer.h>

    class Viewer : public QGLViewer {
    public:
      Viewer() : wireframe_(false), flatShading_(false){};

    protected:
      virtual void draw();
      virtual void init();
      virtual void keyPressEvent(QKeyEvent *e);
      virtual void mousePressEvent(QMouseEvent *e);

      virtual QString helpString() const;

    private:
      bool wireframe_, flatShading_;
    };

## keyboardAndMouse.cpp

    #include "keyboardAndMouse.h"

    #include <QCursor>
    #include <QKeyEvent>
    #include <QMap>
    #include <QMenu>
    #include <QMouseEvent>

    #include <math.h>

    using namespace std;

    // Draws a spiral
    void Viewer::draw() {
      const float nbSteps = 80.0;

      glBegin(GL_QUAD_STRIP);
      for (float i = 0; i < nbSteps; ++i) {
        float ratio = i / nbSteps;
        float angle = 21.0 * ratio;
        float c = cos(angle);
        float s = sin(angle);
        float r1 = 1.0 - 0.8 * ratio;
        float r2 = 0.8 - 0.8 * ratio;
        float alt = ratio - 0.5;
        const float nor = .5;
        const float up = sqrt(1.0 - nor * nor);
        glColor3f(fabs(c), 0.2f, fabs(s));
        glNormal3f(nor * c, up, nor * s);
        glVertex3f(r1 * c, alt, r1 * s);
        glVertex3f(r2 * c, alt + 0.05, r2 * s);
      }
      glEnd();
    }

    void Viewer::init() {
      // Restore previous viewer state.
      restoreStateFromFile();

      /////////////////////////////////////////////////////
      //       Keyboard shortcut customization           //
      //      Changes standard action key bindings       //
      /////////////////////////////////////////////////////

      // Define 'Control+Q' as the new exit shortcut (default was 'Escape')
      setShortcut(EXIT_VIEWER, Qt::CTRL + Qt::Key_Q);

      // Set 'Control+F' as the FPS toggle state key.
      setShortcut(DISPLAY_FPS, Qt::CTRL + Qt::Key_F);

      // Disable draw grid toggle shortcut (default was 'G')
      setShortcut(DRAW_GRID, 0);

      // Add custom key description (see keyPressEvent).
      setKeyDescription(Qt::Key_W, "Toggles wire frame display");
      setKeyDescription(Qt::Key_F, "Toggles flat shading display");

      /////////////////////////////////////////////////////
      //         Mouse bindings customization            //
      //     Changes standard action mouse bindings      //
      /////////////////////////////////////////////////////

      // Left and right buttons together make a camera zoom : emulates a mouse third
      // button if needed.
      setMouseBinding(Qt::Key_Z, Qt::NoModifier, Qt::LeftButton, CAMERA, ZOOM);

      // Disable previous TRANSLATE mouse binding (and remove it from help mouse
      // tab).
      setMouseBinding(Qt::NoModifier, Qt::RightButton, NO_CLICK_ACTION);

      setMouseBinding(Qt::ControlModifier | Qt::ShiftModifier, Qt::RightButton,
                      SELECT);
      setWheelBinding(Qt::AltModifier, CAMERA, MOVE_FORWARD);
      setMouseBinding(Qt::AltModifier, Qt::LeftButton, CAMERA, TRANSLATE);

      // Add custom mouse bindings description (see mousePressEvent())
      setMouseBindingDescription(Qt::NoModifier, Qt::RightButton,
                                 "Opens a camera path context menu");

      // Display the help window. The help window tabs are automatically updated
      // when you define new standard key or mouse bindings (as is done above).
      // Custom bindings descriptions are added using setKeyDescription() and
      // setMouseBindingDescription().
      help();
    }

    ///////////////////////////////////////////////
    //      Define new key bindings : F & W      //
    ///////////////////////////////////////////////

    void Viewer::keyPressEvent(QKeyEvent *e) {
      // Get event modifiers key
      const Qt::KeyboardModifiers modifiers = e->modifiers();

      // A simple switch on e->key() is not sufficient if we want to take state key
      // into account. With a switch, it would have been impossible to separate 'F'
      // from 'CTRL+F'. That's why we use imbricated if...else and a "handled"
      // boolean.
      bool handled = false;
      if ((e->key() == Qt::Key_W) && (modifiers == Qt::NoButton)) {
        wireframe_ = !wireframe_;
        if (wireframe_)
          glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
        else
          glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
        handled = true;
        update();
      } else if ((e->key() == Qt::Key_F) && (modifiers == Qt::NoButton)) {
        flatShading_ = !flatShading_;
        if (flatShading_)
          glShadeModel(GL_FLAT);
        else
          glShadeModel(GL_SMOOTH);
        handled = true;
        update();
      }
      // ... and so on with other else/if blocks.

      if (!handled)
        QGLViewer::keyPressEvent(e);
    }

    ///////////////////////////////////////////////////////////
    //             Define new mouse bindings                 //
    //   A camera viewpoint menu binded on right button      //
    ///////////////////////////////////////////////////////////

    void Viewer::mousePressEvent(QMouseEvent *e) {
      if ((e->button() == Qt::RightButton) && (e->modifiers() == Qt::NoButton)) {
        QMenu menu(this);
        menu.addAction("Camera positions");
        menu.addSeparator();
        QMap<QAction *, int> menuMap;

        bool atLeastOne = false;
        // We only test the 20 first indexes. This is a limitation.
        for (unsigned short i = 0; i < 20; ++i)
          if (camera()->keyFrameInterpolator(i)) {
            atLeastOne = true;
            QString text;
            if (camera()->keyFrameInterpolator(i)->numberOfKeyFrames() == 1)
              text = "Position " + QString::number(i);
            else
              text = "Path " + QString::number(i);

            menuMap[menu.addAction(text)] = i;
          }

        if (!atLeastOne) {
          menu.addAction("No position defined");
          menu.addAction("Use to Alt+Fx to define one");
        }

        QAction *action = menu.exec(e->globalPos());

        if (atLeastOne && action)
          camera()->playPath(menuMap[action]);
      } else
        QGLViewer::mousePressEvent(e);
    }

    QString Viewer::helpString() const {
      QString text("<h2>K e y b o a r d A n d M o u s e</h2>");
      text += "This example illustrates the mouse and key bindings "
              "customization.<br><br>";
      text += "Use <code>setShortcut()</code> to change standard action key "
              "bindings (display of axis, grid or fps, exit shortcut...).<br><br>";
      text += "Use <code>setMouseBinding()</code> and "
              "<code>setWheelBinding()</code> to change standard action mouse "
              "bindings ";
      text += "(camera rotation, translation, object selection...).<br><br>";
      text += "If you want to define <b>new</b> key or mouse actions, overload "
              "<code>keyPressEvent()</code> and/or ";
      text += "<code>mouse(Press|Move|Release)Event()</code> to define and bind "
              "your own new actions. ";
      text += "Use <code>setKeyDescription()</code> and "
              "<code>setMouseBindingDescription()</code> to add a description of "
              "your bindings in the help window.<br><br>";
      text += "In this example, we defined the <b>F</b> and <b>W</b> keys and the "
              "right mouse button opens a popup menu. ";
      text += "See the keyboard and mouse tabs in this help window for the "
              "complete bindings description.<br><br>";
      text += "By the way, exit shortcut has been binded to <b>Ctrl+Q</b>.";
      return text;
    }

## main.cpp

    #include "keyboardAndMouse.h"
    #include <qapplication.h>

    int main(int argc, char **argv) {
      QApplication application(argc, argv);

      Viewer viewer;

      viewer.setWindowTitle("keyboardAndMouse");

      viewer.show();

      return application.exec();
    }

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