CopperSpice API  1.7.2
QLineF Class Reference

The QLineF class provides a two-dimensional vector using floating point precision. More...

## Public Types

enum  IntersectType

## Public Methods

QLineF () = default

QLineF (const QLine &line)

QLineF (const QPointF &point1, const QPointF &point2)

QLineF (qreal x1, qreal y1, qreal x2, qreal y2)

qreal angle () const

qreal angle (const QLineF &lineF) const

qreal angleTo (const QLineF &lineF) const

qreal dx () const

qreal dy () const

IntersectType intersect (const QLineF &lineF, QPointF *intersectionPoint) const

bool isNull () const

qreal length () const

QLineF normalVector () const

bool operator!= (const QLineF &lineF) const

bool operator== (const QLineF &lineF) const

QPointF p1 () const

QPointF p2 () const

QPointF pointAt (qreal pos) const

void setAngle (qreal angle)

void setLength (qreal len)

void setLine (qreal x1, qreal y1, qreal x2, qreal y2)

void setP1 (const QPointF &point)

void setP2 (const QPointF &point)

void setPoints (const QPointF &point1, const QPointF &point2)

QLine toLine () const

void translate (const QPointF &point)

void translate (qreal dx, qreal dy)

QLineF translated (const QPointF &offset) const

QLineF translated (qreal dx, qreal dy) const

QLineF unitVector () const

qreal x1 () const

qreal x2 () const

qreal y1 () const

qreal y2 () const

## Static Public Methods

static QLineF fromPolar (qreal length, qreal angle)

## Related Functions

These are not member functions

QDataStreamoperator<< (QDataStream &stream, const QLineF &lineF)

QDataStreamoperator>> (QDataStream &stream, QLineF &lineF)

## Detailed Description

The QLineF class provides a two-dimensional vector using floating point precision.

A QLineF describes a finite length line (or line segment) on a two-dimensional surface. QLineF defines the start and end points of the line using floating point accuracy for coordinates. Use the toLine() function to retrieve an integer based copy of this line.

The positions of the line's start and end points can be retrieved using the p1(), x1(), y1(), p2(), x2(), and y2() functions. The dx() and dy() functions return the horizontal and vertical components of the line, respectively.

The line's length can be retrieved using the length() function, and altered using the setLength() function. Similarly, angle() and setAngle() are respectively used for retrieving and altering the angle of the line. Use the isNull() function to determine whether the QLineF represents a valid line or a null line.

The intersect() function determines the IntersectType for this line and a given line, while the angle() function returns the angle between the lines. In addition, the unitVector() function returns a line that has the same starting point as this line, but with a length of only 1, while the normalVector() function returns a line that is perpendicular to this line with the same starting point and length.

Finally, the line can be translated a given offset using the translate() function, and can be traversed using the pointAt() function.

QLine, QPolygonF, QRectF

## Member Enumeration Documentation

Describes the intersection between two lines.

 QLineF::UnboundedIntersection QLineF::BoundedIntersection
ConstantValueDescription
QLineF::NoIntersection0 Indicates that the lines do not intersect; i.e. they are parallel.
QLineF::UnboundedIntersection2 The two lines intersect, but not within the range defined by their lengths. This will be the case if the lines are not parallel.

intersect() will also return this value if the intersect point is within the start and end point of only one of the lines.

ConstantValueDescription
QLineF::BoundedIntersection1 The two lines intersect with each other within the start and end points of each line.
intersect()

## Constructor & Destructor Documentation

 QLineF::QLineF ( )
default

Constructs a null line.

 QLineF::QLineF ( const QPointF & point1, const QPointF & point2 )
inline

Constructs a line object that represents the line between point1 and point2.

 QLineF::QLineF ( qreal x1, qreal y1, qreal x2, qreal y2 )
inline

Constructs a line object that represents the line between (x1, y1) and (x2, y2).

 QLineF::QLineF ( const QLine & line )
inline

Construct a QLineF object from the given integer-based line.

toLine()

## Method Documentation

 qreal QLineF::angle ( ) const

Returns the angle of the line in degrees.

The return value will be in the range of values from 0.0 up to but not including 360.0. The angles are measured counter-clockwise from a point on the x-axis to the right of the origin (x > 0).

setAngle()
 qreal QLineF::angle ( const QLineF & lineF ) const
deprecated
Deprecated:
Returns the angle (in degrees) between this line and the given line, taking the direction of the lines into account. If the lines do not intersect within their range, it is the intersection point of the extended lines that serves as origin (see QLineF::UnboundedIntersection).

When the lines are parallel, this function returns 0 if they have the same direction, otherwise it returns 180.

intersect()
 qreal QLineF::angleTo ( const QLineF & lineF ) const

Returns the angle (in positive degrees) from this line to the given lineF, taking the direction of the lines into account. If the lines do not intersect within their range, it is the intersection point of the extended lines that serves as origin (see QLineF::UnboundedIntersection).

The returned value represents the number of degrees you need to add to this line to make it have the same angle as the given lineF, going counter-clockwise.

intersect()
 qreal QLineF::dx ( ) const
inline

Returns the horizontal component of the line's vector. Return value is positive if x2() >= x1() and negative if x2() < x1().

dy(), pointAt()
 qreal QLineF::dy ( ) const
inline

Returns the vertical component of the line's vector. Return value is positive if y2() >= y1() and negative if y2() < y1().

dx(), pointAt()
 QLineF QLineF::fromPolar ( qreal length, qreal angle )
static

Returns a QLineF with the given length and angle. The first point of the line will be on the origin.

Positive values for the angles mean counter-clockwise while negative values mean the clockwise direction. Zero degrees is at the 3 o'clock position.

 IntersectType QLineF::intersect ( const QLineF & lineF, QPointF * intersectionPoint ) const

Returns a value indicating whether or not the current QLineF intersects with the given lineF. The actual intersection point is extracted to intersectionPoint (if the pointer is valid). If the lines are parallel the intersection point is undefined.

 bool QLineF::isNull ( ) const

Returns true if the line is not set up with valid start and end point,, otherwise returns false.

 qreal QLineF::length ( ) const

Returns the length of the line.

setLength()
 QLineF QLineF::normalVector ( ) const
inline

Returns a line that is perpendicular to this line with the same starting point and length.

unitVector()
 bool QLineF::operator!= ( const QLineF & lineF ) const
inline

Returns true if the given lineF is not the same as the current object. A line is different from another line if their start or end points differ, or the internal order of the points is different.

 bool QLineF::operator== ( const QLineF & lineF ) const
inline

Returns true if the given lineF is the same as this line. A line is identical to another line if the start and end points are identical, and the internal order of the points is the same.

 QPointF QLineF::p1 ( ) const
inline

Returns the line's start point.

setP1(), x1(), y1(), p2()
 QPointF QLineF::p2 ( ) const
inline

Returns the line's end point.

setP2(), x2(), y2(), p1()
 QPointF QLineF::pointAt ( qreal pos ) const
inline

Returns the point at the parameterized position specified by pos. The method returns the line's starting point if pos = 0 or the ending point if pos = 1.

dx(), dy()
 void QLineF::setAngle ( qreal angle )

Sets the angle of the line to the given angle (in degrees). This will change the position of the second point of the line such that the line has the given angle.

Positive values for the angles mean counter-clockwise while negative values mean the clockwise direction. Zero degrees is at the 3 o'clock position.

angle()
 void QLineF::setLength ( qreal len )
inline

Sets the length of the line to the given length. QLineF will move the end point - p2() - of the line to give the line its new length. If the given length is negative the angle() is also changed.

If the line is a null line, the length will remain zero regardless of the length specified.

length(), isNull()
 void QLineF::setLine ( qreal x1, qreal y1, qreal x2, qreal y2 )
inline

Sets this line to the start in x1, y1 and end in x2, y2.

setP1(), setP2(), p1(), p2()
 void QLineF::setP1 ( const QPointF & point )
inline

Sets the starting point of this line to point1.

setP2(), p1()
 void QLineF::setP2 ( const QPointF & point )
inline

Sets the end point of this line to point2.

setP1(), p2()
 void QLineF::setPoints ( const QPointF & point1, const QPointF & point2 )
inline

Sets the start point of this line to point1 and the end point of this line to point2.

setP1(), setP2(), p1(), p2()
 QLine QLineF::toLine ( ) const
inline

Returns an integer based copy of this line.

Note that the returned line's start and end points are rounded to the nearest integer.

QLineF()
 void QLineF::translate ( const QPointF & point )
inline

Translates this line by the given offset.

 void QLineF::translate ( qreal dx, qreal dy )
inline

Translates this line the distance specified by dx and dy.

 QLineF QLineF::translated ( const QPointF & offset ) const
inline

Returns this line translated by the given offset.

 QLineF QLineF::translated ( qreal dx, qreal dy ) const
inline

Returns this line translated the distance specified by dx and dy.

 QLineF QLineF::unitVector ( ) const

Returns the unit vector for this line. A unit vector is a line starting at the same point as this line with a length of 1.0.

normalVector()
 qreal QLineF::x1 ( ) const
inline

Returns the x-coordinate of the line's start point.

p1()
 qreal QLineF::x2 ( ) const
inline

Returns the x-coordinate of the line's end point.

p2()
 qreal QLineF::y1 ( ) const
inline

Returns the y-coordinate of the line's start point.

p1()
 qreal QLineF::y2 ( ) const
inline

Returns the y-coordinate of the line's end point.

p2()

## Friends And Related Function Documentation

 QDataStream & operator<< ( QDataStream & stream, const QLineF & lineF )
related

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

Refer to Serializing Data Types for additional information.

 QDataStream & operator>> ( QDataStream & stream, QLineF & lineF )
related

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

Refer to Serializing Data Types for additional information.