\inmodule QtCore More...

#include <qline.h>

Collaboration diagram for QLineF:

Public Types
enum	IntersectionType { NoIntersection , BoundedIntersection , UnboundedIntersection }
	\typealias QLineF::IntersectType More...

using	IntersectType = IntersectionType

Public Member Functions
constexpr	QLineF ()
	Constructs a null line.

constexpr	QLineF (const QPointF &pt1, const QPointF &pt2)
	Constructs a line object that represents the line between p1 and p2.

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

constexpr	QLineF (const QLine &line)
	Construct a QLineF object from the given integer-based line.

constexpr bool	isNull () const
	Returns `true` if the line does not have distinct start and end points; otherwise returns `false`.

constexpr QPointF	p1 () const
	Returns the line's start point.

constexpr QPointF	p2 () const
	Returns the line's end point.

constexpr qreal	x1 () const
	Returns the x-coordinate of the line's start point.

constexpr qreal	y1 () const
	Returns the y-coordinate of the line's start point.

constexpr qreal	x2 () const
	Returns the x-coordinate of the line's end point.

constexpr qreal	y2 () const
	Returns the y-coordinate of the line's end point.

constexpr qreal	dx () const
	Returns the horizontal component of the line's vector.

constexpr qreal	dy () const
	Returns the vertical component of the line's vector.

qreal	length () const
	Returns the length of the line.

void	setLength (qreal len)
	Sets the length of the line to the given finite length.

qreal	angle () const

void	setAngle (qreal angle)

qreal	angleTo (const QLineF &l) const

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.

constexpr QLineF	normalVector () const
	Returns a line that is perpendicular to this line with the same starting point and length.

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

constexpr QPointF	pointAt (qreal t) const
	Returns the point at the position specified by finite parameter t.

void	translate (const QPointF &p)
	Translates this line by the given offset.

void	translate (qreal dx, qreal dy)
	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.

constexpr QLineF	translated (const QPointF &p) const

constexpr QLineF	translated (qreal dx, qreal dy) const
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

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
	Returns `true` if the given line is the same as this line.

constexpr bool	operator!= (const QLineF &d) const
	Returns `true` if the given line is not the same as this line.

constexpr QLine	toLine () const
	Returns an integer-based copy of this line.

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

Related Symbols
(Note that these are not member symbols.)
QDataStream &	operator<< (QDataStream &stream, const QLineF &line)
	Writes the given line to the given stream and returns a reference to the stream.

QDataStream &	operator>> (QDataStream &stream, QLineF &line)
	Reads a line from the given stream into the given line and returns a reference to the stream.

Detailed Description

\inmodule QtCore

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.

\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 181 of file qline.h.

Member Typedef Documentation

◆ IntersectType

using QLineF::IntersectType = IntersectionType

Definition at line 186 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 185 of file qline.h.

Constructor & Destructor Documentation

◆ QLineF() [1/4]

constexpr QLineF::QLineF ( )

inlineconstexpr

Constructs a null line.

Definition at line 250 of file qline.h.

Referenced by fromPolar(), normalVector(), and translated().

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◆ QLineF() [2/4]

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

inlineconstexpr

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

Definition at line 254 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 259 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(), QLine::toLineF()

Definition at line 191 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 558 of file qline.cpp.

References dx(), dy(), qAtan2(), qFuzzyCompare(), qRadiansToDegrees(), QPointF::x(), and QPointF::y().

Referenced by QPainterPath::angleAtPercent(), QQuickMultiPointHandler::angles(), angleTo(), QBezier::inflectionPoints(), qt_getInflectionPoints(), QPinchGestureRecognizer::recognize(), and QSwipeGestureRecognizer::recognize().

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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 767 of file qline.cpp.

References a1, a2, angle(), isNull(), and qFuzzyCompare().

Referenced by adapted_angle_on_x(), and QStroker::joinPoints().

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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 335 of file qline.h.

References QPoint::x(), and QPoint::y().

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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 299 of file qline.h.

References QPoint::x().

Referenced by angle(), QStroker::joinPoints(), length(), normalVector(), qt_stroke_side(), setAngle(), setLength(), glyph_metrics_t::transformed(), unitVector(), and QGraphicsWidgetPrivate::windowFrameMouseMoveEvent().

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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 304 of file qline.h.

References QPoint::y().

Referenced by angle(), QStroker::joinPoints(), length(), normalVector(), qt_stroke_side(), setAngle(), setLength(), glyph_metrics_t::transformed(), unitVector(), and QGraphicsWidgetPrivate::windowFrameMouseMoveEvent().

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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 607 of file qline.cpp.

References QLineF(), qCos(), qDegreesToRadians(), and qSin().

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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 647 of file qline.cpp.

References BoundedIntersection, NoIntersection, qt_is_finite(), UnboundedIntersection, and QPointF::y().

Referenced by QStroker::joinPoints(), qt_quadraticForCubic(), and quadraticForCubic().

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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 284 of file qline.h.

References qFuzzyCompare(), QPoint::x(), and QPoint::y().

Referenced by angleTo(), QBezier::endTangent(), QStroker::processCurrentSubpath(), and QBezier::startTangent().

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◆ length()

qreal QLineF::length ( ) const

Returns the length of the line.

See also: setLength(), isNull()

Definition at line 542 of file qline.cpp.

References dx(), dy(), and qHypot().

Referenced by QBezier::addIfClose(), QGraphicsScenePrivate::findClosestTouchPointId(), QQuickSwipeDelegatePrivate::handleMouseMoveEvent(), QQuickPageIndicatorPrivate::itemAt(), QStroker::joinPoints(), QPainterPath::length(), QScroller::pixelPerMeter(), QDashStroker::processCurrentSubpath(), QPinchGestureRecognizer::recognize(), scoreQuadratic(), setAngle(), setLength(), shift(), and QRasterPaintEngine::stroke().

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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 309 of file qline.h.

References QLineF(), dx(), dy(), and p1().

Referenced by shift().

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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 237 of file qline.h.

References d.

◆ 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 387 of file qline.h.

References d.

◆ p1()

constexpr QPointF QLineF::p1 ( ) const

inlineconstexpr

Returns the line's start point.

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

Definition at line 289 of file qline.h.

Referenced by QSvgLine::bounds(), QPaintEngine::drawLines(), QCoreGraphicsPaintEngine::drawLines(), QSvgLine::fastBounds(), QStroker::joinPoints(), normalVector(), QRasterPaintEnginePrivate::rasterizeLine_dashed(), QRasterPaintEngine::stroke(), unitVector(), and QGraphicsWidgetPrivate::windowFrameMouseMoveEvent().

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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 294 of file qline.h.

Referenced by QSvgLine::bounds(), QPaintEngine::drawLines(), QCoreGraphicsPaintEngine::drawLines(), QSvgLine::fastBounds(), QStroker::joinPoints(), QDashStroker::processCurrentSubpath(), QRasterPaintEnginePrivate::rasterizeLine_dashed(), shift(), QRasterPaintEngine::stroke(), and QGraphicsWidgetPrivate::windowFrameMouseMoveEvent().

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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 351 of file qline.h.

References QPoint::x(), and QPoint::y().

Referenced by QDashStroker::processCurrentSubpath().

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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 585 of file qline.cpp.

References dx(), dy(), length(), qCos(), qDegreesToRadians(), qSin(), QPointF::rx(), QPointF::ry(), QPointF::x(), and QPointF::y().

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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 340 of file qline.h.

References dx(), dy(), length(), Q_ASSERT, qIsFinite(), QPoint::x(), and QPoint::y().

Referenced by QStroker::joinPoints(), qt_stroke_side(), and QRasterPaintEnginePrivate::rasterizeLine_dashed().

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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 380 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 364 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 369 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 374 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(), QLine::toLineF()

Definition at line 358 of file qline.h.

◆ translate() [1/2]

void QLineF::translate ( const QPointF & p )

inline

Translates this line by the given offset.

Definition at line 314 of file qline.h.

Referenced by drawTextItemDecoration(), QStroker::joinPoints(), qt_stroke_side(), and translate().

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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 320 of file qline.h.

References translate().

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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 325 of file qline.h.

References QLineF().

Referenced by translated().

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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 330 of file qline.h.

References translated().

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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 620 of file qline.cpp.

References dx(), dy(), p1(), qAbs(), qHypot(), qWarning, QPointF::x(), and QPointF::y().

Referenced by shift().

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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 264 of file qline.h.

References QPoint::x().

Referenced by QX11PaintEngine::drawLines(), QX11PaintEngine::drawLines(), QStroker::joinPoints(), QTransform::map(), and glyph_metrics_t::transformed().

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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 274 of file qline.h.

References QPoint::x().

Referenced by QX11PaintEngine::drawLines(), QX11PaintEngine::drawLines(), QStroker::joinPoints(), and QTransform::map().

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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 269 of file qline.h.

References QPoint::y().

Referenced by QX11PaintEngine::drawLines(), QX11PaintEngine::drawLines(), QStroker::joinPoints(), QTransform::map(), and glyph_metrics_t::transformed().

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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 279 of file qline.h.

References QPoint::y().

Referenced by QX11PaintEngine::drawLines(), QX11PaintEngine::drawLines(), QStroker::joinPoints(), and QTransform::map().

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Friends And Related Symbol Documentation

◆ operator<<()

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

See also: {Serializing Qt Data Types}

Definition at line 803 of file qline.cpp.

References line.

◆ operator>>()

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

See also: {Serializing Qt Data Types}

Definition at line 818 of file qline.cpp.

References line.

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

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

Public Types

Public Member Functions

Static Public Member Functions

Related Symbols

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 Symbol Documentation

◆ operator<<()

◆ operator>>()