Qt 5.6 | Qt Widgets | Colliding Mice Example | mouse.cpp Example File

Qt 5.6.3 Reference Documentation

# mouse.cpp Example File

graphicsview/collidingmice/mouse.cpp

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      #include "mouse.h"

      #include <QGraphicsScene>
      #include <QPainter>
      #include <QStyleOption>

      #include <math.h>

      static const double Pi = 3.14159265358979323846264338327950288419717;
      static double TwoPi = 2.0 * Pi;

      static qreal normalizeAngle(qreal angle)
      {
          while (angle < 0)
              angle += TwoPi;
          while (angle > TwoPi)
              angle -= TwoPi;
          return angle;
      }

      Mouse::Mouse()
          : angle(0), speed(0), mouseEyeDirection(0),
            color(qrand() % 256, qrand() % 256, qrand() % 256)
      {
          setRotation(qrand() % (360 * 16));
      }

      QRectF Mouse::boundingRect() const
      {
          qreal adjust = 0.5;
          return QRectF(-18 - adjust, -22 - adjust,
                        36 + adjust, 60 + adjust);
      }

      QPainterPath Mouse::shape() const
      {
          QPainterPath path;
          path.addRect(-10, -20, 20, 40);
          return path;
      }

      void Mouse::paint(QPainter *painter, const QStyleOptionGraphicsItem *, QWidget *)
      {
          // Body
          painter->setBrush(color);
          painter->drawEllipse(-10, -20, 20, 40);

          // Eyes
          painter->setBrush(Qt::white);
          painter->drawEllipse(-10, -17, 8, 8);
          painter->drawEllipse(2, -17, 8, 8);

          // Nose
          painter->setBrush(Qt::black);
          painter->drawEllipse(QRectF(-2, -22, 4, 4));

          // Pupils
          painter->drawEllipse(QRectF(-8.0 + mouseEyeDirection, -17, 4, 4));
          painter->drawEllipse(QRectF(4.0 + mouseEyeDirection, -17, 4, 4));

          // Ears
          painter->setBrush(scene()->collidingItems(this).isEmpty() ? Qt::darkYellow : Qt::red);
          painter->drawEllipse(-17, -12, 16, 16);
          painter->drawEllipse(1, -12, 16, 16);

          // Tail
          QPainterPath path(QPointF(0, 20));
          path.cubicTo(-5, 22, -5, 22, 0, 25);
          path.cubicTo(5, 27, 5, 32, 0, 30);
          path.cubicTo(-5, 32, -5, 42, 0, 35);
          painter->setBrush(Qt::NoBrush);
          painter->drawPath(path);
      }

      void Mouse::advance(int step)
      {
          if (!step)
              return;
          // Don't move too far away
          QLineF lineToCenter(QPointF(0, 0), mapFromScene(0, 0));
          if (lineToCenter.length() > 150) {
              qreal angleToCenter = ::acos(lineToCenter.dx() / lineToCenter.length());
              if (lineToCenter.dy() < 0)
                  angleToCenter = TwoPi - angleToCenter;
              angleToCenter = normalizeAngle((Pi - angleToCenter) + Pi / 2);

              if (angleToCenter < Pi && angleToCenter > Pi / 4) {
                  // Rotate left
                  angle += (angle < -Pi / 2) ? 0.25 : -0.25;
              } else if (angleToCenter >= Pi && angleToCenter < (Pi + Pi / 2 + Pi / 4)) {
                  // Rotate right
                  angle += (angle < Pi / 2) ? 0.25 : -0.25;
              }
          } else if (::sin(angle) < 0) {
              angle += 0.25;
          } else if (::sin(angle) > 0) {
              angle -= 0.25;
          }

          // Try not to crash with any other mice
          QList<QGraphicsItem *> dangerMice = scene()->items(QPolygonF()
                                                             << mapToScene(0, 0)
                                                             << mapToScene(-30, -50)
                                                             << mapToScene(30, -50));
          foreach (QGraphicsItem *item, dangerMice) {
              if (item == this)
                  continue;

              QLineF lineToMouse(QPointF(0, 0), mapFromItem(item, 0, 0));
              qreal angleToMouse = ::acos(lineToMouse.dx() / lineToMouse.length());
              if (lineToMouse.dy() < 0)
                  angleToMouse = TwoPi - angleToMouse;
              angleToMouse = normalizeAngle((Pi - angleToMouse) + Pi / 2);

              if (angleToMouse >= 0 && angleToMouse < Pi / 2) {
                  // Rotate right
                  angle += 0.5;
              } else if (angleToMouse <= TwoPi && angleToMouse > (TwoPi - Pi / 2)) {
                  // Rotate left
                  angle -= 0.5;
              }
          }

          // Add some random movement
          if (dangerMice.size() > 1 && (qrand() % 10) == 0) {
              if (qrand() % 1)
                  angle += (qrand() % 100) / 500.0;
              else
                  angle -= (qrand() % 100) / 500.0;
          }

          speed += (-50 + qrand() % 100) / 100.0;

          qreal dx = ::sin(angle) * 10;
          mouseEyeDirection = (qAbs(dx / 5) < 1) ? 0 : dx / 5;

          setRotation(rotation() + dx);
          setPos(mapToParent(0, -(3 + sin(speed) * 3)));
      }