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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;

}

//! [0]

Mouse::Mouse()

    : angle(0), speed(0), mouseEyeDirection(0),

      color(qrand() % 256, qrand() % 256, qrand() % 256)

{

    setRotation(qrand() % (360 * 16));

}

//! [0]

//! [1]

QRectF Mouse::boundingRect() const

{

    qreal adjust = 0.5;

    return QRectF(-18 - adjust, -22 - adjust,

                  36 + adjust, 60 + adjust);

}

//! [1]

//! [2]

QPainterPath Mouse::shape() const

{

    QPainterPath path;

    path.addRect(-10, -20, 20, 40);

    return path;

}

//! [2]

//! [3]

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);

}

//! [3]

//! [4]

void Mouse::advance(int step)

{

    if (!step)

        return;

//! [4]

    // Don't move too far away

//! [5]

    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;

//! [5] //! [6]

    }

//! [6]

    // Try not to crash with any other mice

//! [7]

    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;

//! [7] //! [8]

        }

//! [8] //! [9]

    }

//! [9]

    // Add some random movement

//! [10]

    if (dangerMice.size() > 1 && (qrand() % 10) == 0) {

        if (qrand() % 1)

            angle += (qrand() % 100) / 500.0;

        else

            angle -= (qrand() % 100) / 500.0;

    }

//! [10]

//! [11]

    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)));

}

//! [11]