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1 QPointF Class Reference^{^{[модуль QtCore ]}}

QPointF Class Reference
^{^{[модуль QtCore ]}}

The QPointF class defines a point in the plane using floating point precision. Далее...

 #include <QPointF>

Список всех членов, включая унаследованные

Открытые функции

QPointF ()
QPointF ( const QPoint & point )
QPointF ( qreal x, qreal y )
bool isNull () const
qreal & rx ()
qreal & ry ()
void setX ( qreal x )
void setY ( qreal y )
QPoint toPoint () const
qreal x () const
qreal y () const
QPointF & operator*= ( qreal factor )
QPointF & operator+= ( const QPointF & point )
QPointF & operator-= ( const QPointF & point )
QPointF & operator/= ( qreal divisor )

Связанные не-члены

bool operator!= ( const QPointF & p1, const QPointF & p2 )
const QPointF operator* ( const QPointF & point, qreal factor )
const QPointF operator* ( qreal factor, const QPointF & point )
const QPointF operator+ ( const QPointF & p1, const QPointF & p2 )
const QPointF operator- ( const QPointF & p1, const QPointF & p2 )
const QPointF operator- ( const QPointF & point )
const QPointF operator/ ( const QPointF & point, qreal divisor )
QDataStream & operator<< ( QDataStream & stream, const QPointF & point )
bool operator== ( const QPointF & p1, const QPointF & p2 )
QDataStream & operator>> ( QDataStream & stream, QPointF & point )

Подробное описание

The QPointF class defines a point in the plane using floating point precision.

A point is specified by a x coordinate and an y coordinate which can be accessed using the x() and y() functions. The coordinates of the point are specified using floating point numbers for accuracy. The isNull() function returns true if both x and y are set to 0.0. The coordinates can be set (or altered) using the setX() and setY() functions, or alternatively the rx() and ry() functions which return references to the coordinates (allowing direct manipulation).

Given a point p, the following statements are all equivalent:

 QPointF p;
 
 p.setX(p.x() + 1.0);
 p += QPoint(1.0, 0.0);
 p.rx()++;

A QPointF object can also be used as a vector: Addition and subtraction are defined as for vectors (each component is added separately). A QPointF object can also be divided or multiplied by an int or a qreal.

In addition, the QPointF class provides a constructor converting a QPoint object into a QPointF object, and a corresponding toPoint() function which returns a QPoint copy of this point. Finally, QPointF objects can be streamed as well as compared.

Описание функций-членов

QPointF::QPointF ()

Constructs a null point, i.e. with coordinates (0.0, 0.0)

Смотрите также isNull().

QPointF::QPointF ( const QPoint & point )

Constructs a copy of the given point.

QPointF::QPointF ( qreal x, qreal y )

Constructs a point with the given coordinates (x, y).

bool QPointF::isNull () const

Returns true if both the x and y coordinates are set to 0.0, otherwise returns false.

qreal & QPointF::rx ()

Returns a reference to the x coordinate of this point.

Using a reference makes it possible to directly manipulate x. Пример:

 QPoint p(1.1, 2.5);
 p.rx()--;   // p becomes (0.1, 2.5)

qreal & QPointF::ry ()

Returns a reference to the y coordinate of this point.

Using a reference makes it possible to directly manipulate y. Пример:

 QPoint p(1.1, 2.5);
 p.ry()++;   // p becomes (1.1, 3.5)

void QPointF::setX ( qreal x )

Sets the x coordinate of this point to the given x coordinate.

void QPointF::setY ( qreal y )

Sets the y coordinate of this point to the given y coordinate.

QPoint QPointF::toPoint () const

Rounds the coordinates of this point to the nearest integer, and returns a QPoint object with the rounded coordinates.

qreal QPointF::x () const

Returns the x-coordinate of this point.

qreal QPointF::y () const

Returns the y-coordinate of this point.

QPointF & QPointF::operator= ( qreal factor* )

Multiplies this point's coordinates by the given factor, and returns a reference to this point. Пример:

 QPoint p(-1.1, 4.1);
 p *= 2.5;    // p becomes (-2.75,10.25)

QPointF & QPointF::operator+= ( const QPointF & point )

Adds the given point to this point and returns a reference to this point. Пример:

 QPoint p( 3.1, 7.1);
 QPoint q(-1.0, 4.1);
 p += q;    // p becomes (2.1, 11.2)

QPointF & QPointF::operator-= ( const QPointF & point )

Subtracts the given point from this point and returns a reference to this point. Пример:

 QPoint p( 3.1, 7.1);
 QPoint q(-1.0, 4.1);
 p -= q;    // p becomes (4.1, 3.0)

QPointF & QPointF::operator/= ( qreal divisor )

Divides both x and y by the given divisor, and returns a reference to this point. Пример:

 QPoint p(-2.75, 10.25);
 p /= 2.5;           // p becomes (-1.1,4.1)