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

#include <qline.h>

Public Types
enum	IntersectionType { NoIntersection , BoundedIntersection , UnboundedIntersection }

using	IntersectType = IntersectionType

Public Member Functions
constexpr	QLineF ()

constexpr	QLineF (const QPointF &pt1, const QPointF &pt2)

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

constexpr	QLineF (const QLine &line)

constexpr bool	isNull () const

constexpr QPointF	p1 () const

constexpr QPointF	p2 () const

constexpr qreal	x1 () const

constexpr qreal	y1 () const

constexpr qreal	x2 () const

constexpr qreal	y2 () const

constexpr qreal	dx () const

constexpr qreal	dy () const

qreal	length () const

void	setLength (qreal len)

qreal	angle () const

void	setAngle (qreal angle)

qreal	angleTo (const QLineF &l) const

QLineF	unitVector () const

constexpr QLineF	normalVector () const

IntersectionType	intersects (const QLineF &l, QPointF *intersectionPoint=nullptr) const

constexpr QPointF	pointAt (qreal t) const

void	translate (const QPointF &p)

void	translate (qreal dx, qreal dy)

constexpr QLineF	translated (const QPointF &p) const

constexpr QLineF	translated (qreal dx, qreal dy) const

constexpr QPointF	center () const

void	setP1 (const QPointF &p1)

void	setP2 (const QPointF &p2)

void	setPoints (const QPointF &p1, const QPointF &p2)

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

constexpr bool	operator== (const QLineF &d) const

constexpr bool	operator!= (const QLineF &d) const

constexpr QLine	toLine () const

Static Public Member Functions
static QLineF	fromPolar (qreal length, qreal angle)

Related Functions
(Note that these are not member functions.)
QDataStream &	operator<< (QDataStream &stream, const QLineF &line)

QDataStream &	operator>> (QDataStream &stream, QLineF &line)

Detailed Description

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

\inmodule QtCore

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.

\table \row

\inlineimage qline-point.png
\inlineimage qline-coordinates.png \endtable

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 intersects() function determines the IntersectionType for this line and a given line, while the angleTo() 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.

Definition at line 214 of file qline.h.

Member Typedef Documentation

◆ IntersectType

using QLineF::IntersectType = IntersectionType

Definition at line 219 of file qline.h.

Member Enumeration Documentation

◆ IntersectionType

enum QLineF::IntersectionType

\typealias QLineF::IntersectType

Deprecated:: Use QLineF::IntersectionType instead.

Describes the intersection between two lines.

\table \row

\inlineimage qlinef-unbounded.png
\inlineimage qlinef-bounded.png \row
QLineF::UnboundedIntersection
QLineF::BoundedIntersection \endtable

\value NoIntersection Indicates that the lines do not intersect; i.e. they are parallel.

\value UnboundedIntersection 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.

\value BoundedIntersection The two lines intersect with each other within the start and end points of each line.

See also: intersects()

Enumerator
NoIntersection
BoundedIntersection
UnboundedIntersection

Definition at line 218 of file qline.h.

Constructor & Destructor Documentation

◆ QLineF() [1/4]

constexpr QLineF::QLineF ( )

inlineconstexpr

Constructs a null line.

Definition at line 283 of file qline.h.

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◆ QLineF() [2/4]

constexpr QLineF::QLineF	(	const QPointF &	p1,
		const QPointF &	p2
	)

inlineconstexpr

Constructs a line object that represents the line between p1 and p2.

Definition at line 287 of file qline.h.

◆ QLineF() [3/4]

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

inlineconstexpr

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

Definition at line 292 of file qline.h.

◆ QLineF() [4/4]

QLineF::QLineF ( const QLine & line )

inlineconstexpr

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

See also: toLine()

Definition at line 224 of file qline.h.

Member Function Documentation

◆ angle()

qreal QLineF::angle ( ) const

Since: 4.4

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).

See also: setAngle()

Definition at line 585 of file qline.cpp.

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◆ angleTo()

qreal QLineF::angleTo ( const QLineF & line ) const

Since: 4.4

Returns the angle (in degrees) from this line to the given line, taking the direction of the lines into account. If the lines do not \l{intersects()}{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 line, going counter-clockwise.

See also: intersects()

Definition at line 794 of file qline.cpp.

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◆ center()

constexpr QPointF QLineF::center ( ) const

inlineconstexpr

Since: 5.8

Returns the center point of this line. This is equivalent to 0.5 * p1() + 0.5 * p2().

Definition at line 368 of file qline.h.

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◆ dx()

constexpr qreal QLineF::dx ( ) const

inlineconstexpr

Returns the horizontal component of the line's vector.

See also: dy(), pointAt()

Definition at line 332 of file qline.h.

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◆ dy()

constexpr qreal QLineF::dy ( ) const

inlineconstexpr

Returns the vertical component of the line's vector.

See also: dx(), pointAt()

Definition at line 337 of file qline.h.

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◆ fromPolar()

QLineF QLineF::fromPolar	(	qreal	length,
		qreal	angle
	)

static

Since: 4.4

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.

Definition at line 634 of file qline.cpp.

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◆ intersects()

QLineF::IntersectionType QLineF::intersects	(	const QLineF &	line,
		QPointF *	intersectionPoint = `nullptr`
	)		const

Since: 5.14

Returns a value indicating whether or not this line intersects with the given line.

The actual intersection point is extracted to intersectionPoint (if the pointer is valid). If the lines are parallel, the intersection point is undefined.

Definition at line 674 of file qline.cpp.

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◆ isNull()

constexpr bool QLineF::isNull ( ) const

inlineconstexpr

Returns true if the line does not have distinct start and end points; otherwise returns false. The start and end points are considered distinct if qFuzzyCompare() can distinguish them in at least one coordinate.

Note: Due to the use of fuzzy comparison, isNull() may return true for lines whose length() is not zero.

See also: qFuzzyCompare(), length()

Definition at line 317 of file qline.h.

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◆ length()

qreal QLineF::length ( ) const

Returns the length of the line.

See also: setLength(), isNull()

Definition at line 569 of file qline.cpp.

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◆ normalVector()

constexpr QLineF QLineF::normalVector ( ) const

inlineconstexpr

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

See also: unitVector()

Definition at line 342 of file qline.h.

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◆ operator!=()

bool QLineF::operator!= ( const QLineF & line ) const

inlineconstexpr

Returns true if the given line is not the same as this line.

A line is different from another line if their start or end points differ, or the internal order of the points is different.

Definition at line 270 of file qline.h.

◆ operator==()

constexpr bool QLineF::operator== ( const QLineF & line ) const

inlineconstexpr

Returns true if the given line 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.

Definition at line 418 of file qline.h.

◆ p1()

constexpr QPointF QLineF::p1 ( ) const

inlineconstexpr

Returns the line's start point.

See also: x1(), y1(), p2()

Definition at line 322 of file qline.h.

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◆ p2()

constexpr QPointF QLineF::p2 ( ) const

inlineconstexpr

Returns the line's end point.

See also: x2(), y2(), p1()

Definition at line 327 of file qline.h.

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◆ pointAt()

constexpr QPointF QLineF::pointAt ( qreal t ) const

inlineconstexpr

Returns the point at the position specified by finite parameter t. The function returns the line's start point if t = 0, and its end point if t = 1.

See also: dx(), dy()

Definition at line 384 of file qline.h.

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◆ setAngle()

void QLineF::setAngle ( qreal angle )

Since: 4.4

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.

See also: angle()

Definition at line 612 of file qline.cpp.

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◆ setLength()

void QLineF::setLength ( qreal length )

inline

Sets the length of the line to the given finite length. QLineF will move the end point - p2() - of the line to give the line its new length, unless length() was previously zero, in which case no scaling is attempted.

See also: length(), unitVector()

Definition at line 373 of file qline.h.

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◆ setLine()

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

inline

Since: 4.4

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

See also: setP1(), setP2(), p1(), p2()

Definition at line 411 of file qline.h.

◆ setP1()

void QLineF::setP1 ( const QPointF & p1 )

inline

Since: 4.4

Sets the starting point of this line to p1.

See also: setP2(), p1()

Definition at line 395 of file qline.h.

◆ setP2()

void QLineF::setP2 ( const QPointF & p2 )

inline

Since: 4.4

Sets the end point of this line to p2.

See also: setP1(), p2()

Definition at line 400 of file qline.h.

◆ setPoints()

void QLineF::setPoints	(	const QPointF &	p1,
		const QPointF &	p2
	)

inline

Since: 4.4

Sets the start point of this line to p1 and the end point of this line to p2.

See also: setP1(), setP2(), p1(), p2()

Definition at line 405 of file qline.h.

◆ toLine()

constexpr QLine QLineF::toLine ( ) const

inlineconstexpr

Returns an integer-based copy of this line.

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

See also: QLineF()

Definition at line 389 of file qline.h.

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◆ translate() [1/2]

void QLineF::translate ( const QPointF & offset )

inline

Translates this line by the given offset.

Definition at line 347 of file qline.h.

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◆ translate() [2/2]

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

inline

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Translates this line the distance specified by dx and dy.

Definition at line 353 of file qline.h.

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◆ translated() [1/2]

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

inlineconstexpr

Since: 4.4

Returns this line translated by the given offset.

Definition at line 358 of file qline.h.

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◆ translated() [2/2]

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

inlineconstexpr

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Since: 4.4

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

Definition at line 363 of file qline.h.

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◆ unitVector()

QLineF QLineF::unitVector ( ) const

Returns the unit vector for this line, i.e a line starting at the same point as this line with a length of 1.0, provided the line is non-null.

See also: normalVector(), setLength()

Definition at line 647 of file qline.cpp.

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◆ x1()

constexpr qreal QLineF::x1 ( ) const

inlineconstexpr

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

See also: p1()

Definition at line 297 of file qline.h.

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◆ x2()

constexpr qreal QLineF::x2 ( ) const

inlineconstexpr

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

See also: p2()

Definition at line 307 of file qline.h.

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◆ y1()

constexpr qreal QLineF::y1 ( ) const

inlineconstexpr

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

See also: p1()

Definition at line 302 of file qline.h.

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◆ y2()

constexpr qreal QLineF::y2 ( ) const

inlineconstexpr

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

See also: p2()

Definition at line 312 of file qline.h.

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Friends And Related Function Documentation

◆ operator<<()

QDataStream & operator<<	(	QDataStream &	stream,
		const QLineF &	line
	)

See also: {Serializing Qt Data Types}

Definition at line 830 of file qline.cpp.

◆ operator>>()

QDataStream & operator>>	(	QDataStream &	stream,
		QLineF &	line
	)

See also: {Serializing Qt Data Types}

Definition at line 845 of file qline.cpp.

The documentation for this class was generated from the following files:

src/corelib/tools/qline.h
src/corelib/tools/qline.cpp

Public Types

Public Member Functions

Static Public Member Functions

Related Functions

Detailed Description

Member Typedef Documentation

◆ IntersectType

Member Enumeration Documentation

◆ IntersectionType

Constructor & Destructor Documentation

◆ QLineF() [1/4]

◆ QLineF() [2/4]

◆ QLineF() [3/4]

◆ QLineF() [4/4]

Member Function Documentation

◆ angle()

◆ angleTo()

◆ center()

◆ dx()

◆ dy()

◆ fromPolar()

◆ intersects()

◆ isNull()

◆ length()

◆ normalVector()

◆ operator!=()

◆ operator==()

◆ p1()

◆ p2()

◆ pointAt()

◆ setAngle()

◆ setLength()

◆ setLine()

◆ setP1()

◆ setP2()

◆ setPoints()

◆ toLine()

◆ translate() [1/2]

◆ translate() [2/2]

◆ translated() [1/2]

◆ translated() [2/2]

◆ unitVector()

◆ x1()

◆ x2()

◆ y1()

◆ y2()

Friends And Related Function Documentation

◆ operator<<()

◆ operator>>()