# QVector2D Class

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

 Header: #include qmake: QT += gui Since: Qt 4.6

## Public Functions

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

## Static Public Members

 float dotProduct(const QVector2D &v1, const QVector2D &v2)
 bool qFuzzyCompare(const QVector2D &v1, const QVector2D &v2) bool operator!=(const QVector2D &v1, const QVector2D &v2) const QVector2D operator*(float factor, const QVector2D &vector) const QVector2D operator*(const QVector2D &vector, float 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, float divisor) const QVector2D operator/(const QVector2D &vector, const QVector2D &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.

See also QVector3D, QVector4D, and QQuaternion.

## Member Function Documentation

### QVector2D::QVector2D()

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

### QVector2D::QVector2D(floatxpos, floatypos)

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.

See also toVector3D().

### 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.

See also toVector4D().

### float QVector2D::distanceToLine(const QVector2D &point, const QVector2D &direction) const

Returns the distance that this vertex is from a line defined by point and the unit vector direction.

If direction is a null vector, then it does not define a line. In that case, the distance from point to this vertex is returned.

This function was introduced in Qt 5.1.

See also distanceToPoint().

### float QVector2D::distanceToPoint(const QVector2D &point) const

Returns the distance from this vertex to a point defined by the vertex point.

This function was introduced in Qt 5.1.

See also distanceToLine().

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

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`.

### float QVector2D::length() const

Returns the length of the vector from the origin.

See also lengthSquared() and normalized().

### float 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.

See also length() and dotProduct().

### 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.

See also length() and normalized().

### 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.

See also length() and normalize().

### void QVector2D::setX(floatx)

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

See also x() and setY().

### void QVector2D::setY(floaty)

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

See also y() and setX().

### QPoint QVector2D::toPoint() const

Returns the QPoint form of this 2D vector.

See also toPointF() and toVector3D().

### QPointF QVector2D::toPointF() const

Returns the QPointF form of this 2D vector.

See also toPoint() and toVector3D().

### QVector3D QVector2D::toVector3D() const

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

See also toVector4D() and toPoint().

### QVector4D QVector2D::toVector4D() const

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

See also toVector3D() and toPoint().

### float QVector2D::x() const

Returns the x coordinate of this point.

See also setX() and y().

### float QVector2D::y() const

Returns the y coordinate of this point.

See also setY() and x().

### QVector2D::operator QVariant() const

Returns the 2D vector as a QVariant.

### QVector2D &QVector2D::operator*=(floatfactor)

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

See also operator/=().

### 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.

See also operator-=().

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

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

See also operator+=().

### QVector2D &QVector2D::operator/=(floatdivisor)

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

See also operator*=().

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

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

This function was introduced in Qt 5.5.

See also operator*=().

### float &QVector2D::operator[](inti)

Returns the component of the vector at index position i as a modifiable reference.

i must be a valid index position in the vector (i.e., 0 <= i < 2).

This function was introduced in Qt 5.2.

### float QVector2D::operator[](inti) const

Returns the component of the vector at index position i.

i must be a valid index position in the vector (i.e., 0 <= i < 2).

This function was introduced in Qt 5.2.

## Related Non-Members

### boolqFuzzyCompare(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.

### booloperator!=(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 QVector2Doperator*(floatfactor, const QVector2D &vector)

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

See also QVector2D::operator*=().

### const QVector2Doperator*(const QVector2D &vector, floatfactor)

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

See also QVector2D::operator*=().

### const QVector2Doperator*(const QVector2D &v1, const QVector2D &v2)

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

### const QVector2Doperator+(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.

See also QVector2D::operator+=().

### const QVector2Doperator-(const QVector2D &v1, const QVector2D &v2)

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

See also QVector2D::operator-=().

### const QVector2Doperator-(const QVector2D &vector)

This is an overloaded function.

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 QVector2Doperator/(const QVector2D &vector, floatdivisor)

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

See also QVector2D::operator/=().

### const QVector2Doperator/(const QVector2D &vector, const QVector2D &divisor)

Returns the QVector2D object formed by dividing components of the given vector by a respective components of the given divisor.

This function was introduced in Qt 5.5.

See also QVector2D::operator/=().

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

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

See also Serializing Qt Data Types.

### booloperator==(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.

See also Serializing Qt Data Types.

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