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# mouse.cpp Example File
graphicsview/collidingmice/mouse.cpp

        /****************************************************************************
        **
        ** Copyright (C) 2006-2006 Trolltech ASA. All rights reserved.
        **
        ** This file is part of the example classes of the Qt Toolkit.
        **
        ** Licensees holding valid Qt Preview licenses may use this file in
        ** accordance with the Qt Preview License Agreement provided with the
        ** Software.
        **
        ** See http://www.trolltech.com/pricing.html or email sales@trolltech.com for
        ** information about Qt Commercial License Agreements.
        **
        ** Contact info@trolltech.com if any conditions of this licensing are
        ** not clear to you.
        **
        ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
        ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
        **
        ****************************************************************************/

        #include "mouse.h"

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

        #include <cmath>

        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(rand() % 256, rand() % 256, rand() % 256)
        {
            rotate(rand() % (360 * 16));
            startTimer(1000 / 33);
        }

        QRectF Mouse::boundingRect() const
        {
            qreal adjust = 0.5;
            return QRectF(-20 - adjust, -22 - adjust,
                          40 + adjust, 83 + 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::timerEvent(QTimerEvent *)
        {
            // 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 && (rand() % 10) == 0) {
                if (rand() % 1)
                    angle += (rand() % 100) / 500.0;
                else
                    angle -= (rand() % 100) / 500.0;
            }

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

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

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