QPointF Class

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

Header:	#include <QPointF>
qmake:	QT += core

• List of all members, including inherited members

Note: All functions in this class are reentrant.

Public Functions

	QPointF(qreal xpos, qreal ypos)
	QPointF(const QPoint &point)
	QPointF()
bool	isNull() const
qreal	manhattanLength() const
qreal &	rx()
qreal &	ry()
void	setX(qreal x)
void	setY(qreal y)
CGPoint	toCGPoint() const
QPoint	toPoint() const
QPointF	transposed() 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)

Static Public Members

qreal	dotProduct(const QPointF &p1, const QPointF &p2)
QPointF	fromCGPoint(CGPoint point)

Related Non-Members

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 &point)
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)

Detailed Description

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 += QPointF(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.

Member Function Documentation

QPointF::QPointF(qreal xpos, qreal ypos)

Constructs a point with the given coordinates (xpos, ypos).

See also setX() and setY().

QPointF::QPointF(const QPoint &point)

Constructs a copy of the given point.

See also toPoint().

QPointF::QPointF()

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

See also isNull().

[static] qreal QPointF::dotProduct(const QPointF &p1, const QPointF &p2)

QPointF p( 3.1, 7.1);
QPointF q(-1.0, 4.1);
int lengthSquared = QPointF::dotProduct(p, q);   // lengthSquared becomes 26.01

Returns the dot product of p1 and p2.

This function was introduced in Qt 5.1.

[static] QPointF QPointF::fromCGPoint(CGPoint point)

Creates a QRectF from CGPoint point.

This function was introduced in Qt 5.8.

See also toCGPoint().

bool QPointF::isNull() const

Returns true if both the x and y coordinates are set to 0.0 (ignoring the sign); otherwise returns false.

qreal QPointF::manhattanLength() const

Returns the sum of the absolute values of x() and y(), traditionally known as the "Manhattan length" of the vector from the origin to the point.

This function was introduced in Qt 4.6.

See also QPoint::manhattanLength().

qreal &QPointF::rx()

Returns a reference to the x coordinate of this point.

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

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

See also x() and setX().

qreal &QPointF::ry()

Returns a reference to the y coordinate of this point.

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

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

See also y() and setY().

void QPointF::setX(qreal x)

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

See also x() and setY().

void QPointF::setY(qreal y)

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

See also y() and setX().

CGPoint QPointF::toCGPoint() const

Creates a CGPoint from a QPointF.

This function was introduced in Qt 5.8.

See also fromCGPoint().

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().

QPointF QPointF::transposed() const

Returns a point with x and y coordinates exchanged:

QPointF{1.0, 2.0}.transposed() // {2.0, 1.0}

This function was introduced in Qt 5.14.

See also x(), y(), setX(), and setY().

qreal QPointF::x() const

Returns the x coordinate of this point.

See also setX() and rx().

qreal QPointF::y() const

Returns the y coordinate of this point.

See also setY() and ry().

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

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

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

See also operator/=().

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

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

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

See also operator-=().

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

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

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

See also operator+=().

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

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

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

See also operator*=().