Car Class Reference

#include <car.h>

Inheritance diagram for Car:

[legend]Collaboration diagram for Car:

[legend]List of all members.

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Detailed Description

Definition at line 31 of file car.h.

Public Slots
void	accelerate ()
void	decelerate ()
void	turnLeft ()
void	turnRight ()
Signals
void	crashed ()
Public Member Functions
	Car ()
QRectF	boundingRect () const
Protected Member Functions
void	paint (QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget=0)
void	timerEvent (QTimerEvent *event)
Private Attributes
QBrush	color
qreal	wheelsAngle
qreal	speed

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Constructor & Destructor Documentation

Car::Car

(

)

Definition at line 35 of file car.cpp.

References QGraphicsItem::ItemIsFocusable, QGraphicsItem::ItemIsMovable, QGraphicsItem::setFlag(), and QObject::startTimer().

         : color(Qt::green), wheelsAngle(0), speed(0)
{
    startTimer(1000 / 33);
    setFlag(QGraphicsItem::ItemIsMovable, true);
    setFlag(QGraphicsItem::ItemIsFocusable, true);
}

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Member Function Documentation

QRectF Car::boundingRect

(

)

const [virtual]

This pure virtual function defines the outer bounds of the item as a rectangle; all painting must be restricted to inside an item's bounding rect. QGraphicsView uses this to determine whether the item requires redrawing.

Although the item's shape can be arbitrary, the bounding rect is always rectangular, and it is unaffected by the items' transformation (scale(), rotate(), etc.).

Reimplement this function to let QGraphicsView determine what parts of the widget, if any, need to be redrawn.

Note: For shapes that paint an outline / stroke, it is important to include half the pen width in the bounding rect. It is not necessary to compensate for antialiasing, though.

Example:

    QRectF CircleItem::boundingRect() const
    {
        qreal penWidth = 1;
        return QRectF(-radius - penWidth / 2, -radius - penWidth / 2,
                      diameter + penWidth, diameter + penWidth);
    }

See also:

shape(), contains(), {The Graphics View Coordinate System}

Implements QGraphicsItem.

Definition at line 30 of file car.cpp.

{
    return QRectF(-35, -81, 70, 115);
}

void Car::accelerate

(

)

[slot]

Definition at line 42 of file car.cpp.

References speed.

{
    if (speed < 10)
        ++speed;
}

void Car::decelerate

(

)

[slot]

Definition at line 48 of file car.cpp.

References speed.

{
    if (speed > -10)
        --speed;
}

void Car::turnLeft

(

)

[slot]

Definition at line 54 of file car.cpp.

References wheelsAngle.

{
    if (wheelsAngle > -30)
        wheelsAngle -= 5;
}

void Car::turnRight

(

)

[slot]

Definition at line 60 of file car.cpp.

References wheelsAngle.

{
    if (wheelsAngle < 30)
       wheelsAngle += 5;
}

void Car::crashed

(

)

[signal]

void Car::paint	(	QPainter *	painter,
		const QStyleOptionGraphicsItem *	option,
		QWidget *	widget = 0
	)			[protected, virtual]

This function, which is usually called by QGraphicsView, paints the contents of an item in local coordinates.

Reimplement this function in a QGraphicsItem subclass to provide the item's painting implementation, using painter. The option parameter provides style options for the item, such as its state, exposed area and its level-of-detail hints. The widget argument is optional. If provided, it points to the widget that is being painted on; otherwise, it is 0.

        void RoundRectItem::paint(QPainter *painter,
                                  const QStyleOptionGraphicsItem *option,
                                  QWidget *widget)
        {
            painter->drawRoundRect(-10, -10, 20, 20);
        }

The painter's pen is 0-width by default, and its pen is initialized to the QPalette::Text brush from the paint device's palette. The brush is initialized to QPalette::Window.

All painting is done in local coordinates.

Implements QGraphicsItem.

Definition at line 66 of file car.cpp.

References Qt::black, color, QPainter::drawEllipse(), QPainter::drawPie(), QPainter::drawRect(), Qt::gray, QPainter::restore(), QPainter::rotate(), QPainter::save(), QPainter::setBrush(), QPainter::translate(), and wheelsAngle.

{
    Q_UNUSED(option);
    Q_UNUSED(widget);

    painter->setBrush(Qt::gray);
    painter->drawRect(-20, -58, 40, 2); // front axel
    painter->drawRect(-20, 7, 40, 2); // rear axel

    painter->setBrush(color);
    painter->drawRect(-25, -79, 50, 10); // front wing

    painter->drawEllipse(-25, -48, 50, 20); // side pods
    painter->drawRect(-25, -38, 50, 35); // side pods
    painter->drawRect(-5, 9, 10, 10); // back pod

    painter->drawEllipse(-10, -81, 20, 100); // main body

    painter->drawRect(-17, 19, 34, 15); // rear wing

    painter->setBrush(Qt::black);
    painter->drawPie(-5, -51, 10, 15, 0, 180 * 16);
    painter->drawRect(-5, -44, 10, 10); // cocpit

    painter->save();
    painter->translate(-20, -58);
    painter->rotate(wheelsAngle);
    painter->drawRect(-10, -7, 10, 15); // front left
    painter->restore();

    painter->save();
    painter->translate(20, -58);
    painter->rotate(wheelsAngle);
    painter->drawRect(0, -7, 10, 15); // front left
    painter->restore();

    painter->drawRect(-30, 0, 12, 17); // rear left
    painter->drawRect(19, 0, 12, 17);  // rear right
}

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void Car::timerEvent

(

QTimerEvent *

event

)

[protected, virtual]

This event handler can be reimplemented in a subclass to receive timer events for the object.

QTimer provides a higher-level interface to the timer functionality, and also more general information about timers. The timer event is passed in the event parameter.

See also:

startTimer(), killTimer(), event()

Reimplemented from QObject.

Definition at line 106 of file car.cpp.

References QObject::event(), Pi, QGraphicsItem::rotate(), speed, QGraphicsItem::translate(), QGraphicsItem::update(), and wheelsAngle.

{
    Q_UNUSED(event);

    const qreal axelDistance = 54;
    qreal wheelsAngleRads = (wheelsAngle * Pi) / 180;
    qreal turnDistance = ::cos(wheelsAngleRads) * axelDistance * 2;
    qreal turnRateRads = wheelsAngleRads / turnDistance;  // rough estimate
    qreal turnRate = (turnRateRads * 180) / Pi;
    qreal rotation = speed * turnRate;
    
    rotate(rotation);
    translate(0, -speed);
    update();
}

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Member Data Documentation

QBrush Car::color [private]

Definition at line 53 of file car.h.

Referenced by paint().

qreal Car::wheelsAngle [private]

Definition at line 54 of file car.h.

Referenced by paint(), timerEvent(), turnLeft(), and turnRight().

qreal Car::speed [private]

Definition at line 55 of file car.h.

Referenced by accelerate(), decelerate(), and timerEvent().

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The documentation for this class was generated from the following files:

• examples/qdbus/remotecontrolledcar/car/car.h
• examples/qdbus/remotecontrolledcar/car/car.cpp

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