Qt:Документация 4.3.2/qpointf

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[править] QPointF Class Reference
[модуль QtCore ]

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

 #include <QPointF>

[править] Открытые функции

[править] 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 )

[править] 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.

See also QPoint and QPolygonF.


[править] Описание функций-членов

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QPointF::QPointF ()

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

Смотрите также isNull().

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QPointF::QPointF ( const QPoint & point )

Constructs a copy of the given point.

See also toPoint().

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QPointF::QPointF ( qreal x, qreal y )

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

See also setX() and setY().

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bool QPointF::isNull () const

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

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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)

See also x() and setX().

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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)

See also y() and setY().

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void QPointF::setX ( qreal x )

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

See also x() and setY().

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void QPointF::setY ( qreal y )

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

See also y() and setX().

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QPoint QPointF::toPoint () const

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

See also QPointF().

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qreal QPointF::x () const

Returns the x-coordinate of this point.

See also setX() and rx().

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qreal QPointF::y () const

Returns the y-coordinate of this point.

See also setY() and ry().

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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)

See also operator/=().

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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)

See also operator-=().

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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)

See also operator+=().

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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)

See also operator*=().


[править] Связанные не-члены

[править]
bool operator!= ( const QPointF & p1, const QPointF & p2 )

Эта перегруженная функция предоставлена для удобства.

Returns true if p1 is not equal to p2; otherwise returns false.

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const QPointF operator* ( const QPointF & point, qreal factor )

Эта перегруженная функция предоставлена для удобства.

Returns a copy of the given point, multiplied by the given factor.

See also QPointF::operator*=().

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const QPointF operator* ( qreal factor, const QPointF & point )

Эта перегруженная функция предоставлена для удобства.

Returns a copy of the given point, multiplied by the given factor.

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const QPointF operator+ ( const QPointF & p1, const QPointF & p2 )

Эта перегруженная функция предоставлена для удобства.

Returns a QPointF object that is the sum of the given points, p1 and p2; each component is added separately.

See also QPointF::operator+=().

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const QPointF operator- ( const QPointF & p1, const QPointF & p2 )

Эта перегруженная функция предоставлена для удобства.

Returns a QPointF object that is formed by subtracting p2 from p1; each component is subtracted separately.

See also QPointF::operator-=().

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const QPointF operator- ( const QPointF & point )

Эта перегруженная функция предоставлена для удобства.

Returns a QPointF object that is formed by changing the sign of both components of the given point.

Equivalent to QPointF(0,0) - point.

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const QPointF operator/ ( const QPointF & point, qreal divisor )

Эта перегруженная функция предоставлена для удобства.

Returns the QPointF object formed by dividing both components of the given point by the given divisor.

See also QPointF::operator/=().

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QDataStream & operator<< ( QDataStream & stream, const QPointF & point )

Эта перегруженная функция предоставлена для удобства.

Writes the given point to the given stream and returns a reference to the stream.

Смотрите также Формат операторов QDataStream.

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bool operator== ( const QPointF & p1, const QPointF & p2 )

Эта перегруженная функция предоставлена для удобства.

Returns true if p1 is equal to p2; otherwise returns false.

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QDataStream & operator>> ( QDataStream & stream, QPointF & point )

Эта перегруженная функция предоставлена для удобства.

Reads a point from the given stream into the given point and returns a reference to the stream.

Смотрите также Формат операторов QDataStream.



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Qt 4.3.2