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# QVector2D Class Reference[QtGui module]

The QVector2D class represents a vector or vertex in 2D space. More...

` #include <QVector2D>`

This class was introduced in Qt 4.6.

## Public Functions

 QVector2D () QVector2D ( qreal xpos, qreal ypos ) QVector2D ( const QPoint & point ) QVector2D ( const QPointF & point ) QVector2D ( const QVector3D & vector ) QVector2D ( const QVector4D & vector ) bool isNull () const qreal length () const qreal lengthSquared () const void normalize () QVector2D normalized () const void setX ( qreal x ) void setY ( qreal y ) QPoint toPoint () const QPointF toPointF () const QVector3D toVector3D () const QVector4D toVector4D () const qreal x () const qreal y () const operator QVariant () const QVector2D & operator*= ( qreal factor ) QVector2D & operator*= ( const QVector2D & vector ) QVector2D & operator+= ( const QVector2D & vector ) QVector2D & operator-= ( const QVector2D & vector ) QVector2D & operator/= ( qreal divisor )

## Static Public Members

 qreal dotProduct ( const QVector2D & v1, const QVector2D & v2 )

## Related Non-Members

 bool qFuzzyCompare ( const QVector2D & v1, const QVector2D & v2 ) bool operator!= ( const QVector2D & v1, const QVector2D & v2 ) const QVector2D operator* ( qreal factor, const QVector2D & vector ) const QVector2D operator* ( const QVector2D & vector, qreal factor ) const QVector2D operator* ( const QVector2D & v1, const QVector2D & v2 ) const QVector2D operator+ ( const QVector2D & v1, const QVector2D & v2 ) const QVector2D operator- ( const QVector2D & v1, const QVector2D & v2 ) const QVector2D operator- ( const QVector2D & vector ) const QVector2D operator/ ( const QVector2D & vector, qreal divisor ) QDataStream & operator<< ( QDataStream & stream, const QVector2D & vector ) bool operator== ( const QVector2D & v1, const QVector2D & v2 ) QDataStream & operator>> ( QDataStream & stream, QVector2D & vector )

## Detailed Description

The QVector2D class represents a vector or vertex in 2D space.

The QVector2D class can also be used to represent vertices in 2D space. We therefore do not need to provide a separate vertex class.

## Member Function Documentation

### QVector2D::QVector2D ()

Constructs a null vector, i.e. with coordinates (0, 0, 0).

### QVector2D::QVector2D ( qreal xpos, qreal ypos )

Constructs a vector with coordinates (xpos, ypos).

### QVector2D::QVector2D ( const QPoint & point )

Constructs a vector with x and y coordinates from a 2D point.

### QVector2D::QVector2D ( const QPointF & point )

Constructs a vector with x and y coordinates from a 2D point.

### QVector2D::QVector2D ( const QVector3D & vector )

Constructs a vector with x and y coordinates from a 3D vector. The z coordinate of vector is dropped.

### QVector2D::QVector2D ( const QVector4D & vector )

Constructs a vector with x and y coordinates from a 3D vector. The z and w coordinates of vector are dropped.

### qreal QVector2D::dotProduct ( const QVector2D & v1, const QVector2D & v2 )   [static]

Returns the dot product of v1 and v2.

### bool QVector2D::isNull () const

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

### qreal QVector2D::length () const

Returns the length of the vector from the origin.

### qreal QVector2D::lengthSquared () const

Returns the squared length of the vector from the origin. This is equivalent to the dot product of the vector with itself.

### void QVector2D::normalize ()

Normalizes the currect vector in place. Nothing happens if this vector is a null vector or the length of the vector is very close to 1.

### QVector2D QVector2D::normalized () const

Returns the normalized unit vector form of this vector.

If this vector is null, then a null vector is returned. If the length of the vector is very close to 1, then the vector will be returned as-is. Otherwise the normalized form of the vector of length 1 will be returned.

### void QVector2D::setX ( qreal x )

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

### void QVector2D::setY ( qreal y )

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

### QPoint QVector2D::toPoint () const

Returns the QPoint form of this 2D vector.

### QPointF QVector2D::toPointF () const

Returns the QPointF form of this 2D vector.

### QVector3D QVector2D::toVector3D () const

Returns the 3D form of this 2D vector, with the z coordinate set to zero.

### QVector4D QVector2D::toVector4D () const

Returns the 4D form of this 2D vector, with the z and w coordinates set to zero.

### qreal QVector2D::x () const

Returns the x coordinate of this point.

### qreal QVector2D::y () const

Returns the y coordinate of this point.

### QVector2D::operator QVariant () const

Returns the 2D vector as a QVariant.

QVector2D & QVector2D::operator*= ( qreal factor )

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

### QVector2D & QVector2D::operator*= ( const QVector2D & vector )

Multiplies the components of this vector by the corresponding components in vector.

QVector2D & QVector2D::operator+= ( const QVector2D & vector )

Adds the given vector to this vector and returns a reference to this vector.

QVector2D & QVector2D::operator-= ( const QVector2D & vector )

Subtracts the given vector from this vector and returns a reference to this vector.

### QVector2D & QVector2D::operator/= ( qreal divisor )

Divides this vector's coordinates by the given divisor, and returns a reference to this vector.

## Related Non-Members

### bool qFuzzyCompare ( const QVector2D & v1, const QVector2D & v2 )

Returns true if v1 and v2 are equal, allowing for a small fuzziness factor for floating-point comparisons; false otherwise.

### bool operator!= ( const QVector2D & v1, const QVector2D & v2 )

Returns true if v1 is not equal to v2; otherwise returns false. This operator uses an exact floating-point comparison.

### const QVector2D operator* ( qreal factor, const QVector2D & vector )

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

### const QVector2D operator* ( const QVector2D & vector, qreal factor )

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

### const QVector2D operator* ( const QVector2D & v1, const QVector2D & v2 )

Multiplies the components of v1 by the corresponding components in v2.

### const QVector2D operator+ ( const QVector2D & v1, const QVector2D & v2 )

Returns a QVector2D object that is the sum of the given vectors, v1 and v2; each component is added separately.

### const QVector2D operator- ( const QVector2D & v1, const QVector2D & v2 )

Returns a QVector2D object that is formed by subtracting v2 from v1; each component is subtracted separately.

### const QVector2D operator- ( const QVector2D & vector )

Returns a QVector2D object that is formed by changing the sign of the components of the given vector.

Equivalent to QVector2D(0,0) - vector.

### const QVector2D operator/ ( const QVector2D & vector, qreal divisor )

Returns the QVector2D object formed by dividing all three components of the given vector by the given divisor.

### QDataStream & operator<< ( QDataStream & stream, const QVector2D & vector )

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

### bool operator== ( const QVector2D & v1, const QVector2D & v2 )

Returns true if v1 is equal to v2; otherwise returns false. This operator uses an exact floating-point comparison.

### QDataStream & operator>> ( QDataStream & stream, QVector2D & vector )

Reads a 2D vector from the given stream into the given vector and returns a reference to the stream. Publicité

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