QLine Class Reference

The QLine class provides a two-dimensional vector using integer precision. More...

#include <qline.h>

Public Functions
int	dx () const
	Returns the horizontal component of the line's vector. More...
int	dy () const
	Returns the vertical component of the line's vector. More...
bool	isNull () const
	Returns true if the line is not set up with valid start and end point; otherwise returns false. More...
bool	operator!= (const QLine &d) const
	Returns true if the given line is not the same as this line. More...
bool	operator== (const QLine &d) const
	Returns true if the given line is the same as this line. More...
QPoint	p1 () const
	Returns the line's start point. More...
QPoint	p2 () const
	Returns the line's end point. More...
	QLine ()
	Constructs a null line. More...
	QLine (const QPoint &pt1, const QPoint &pt2)
	Constructs a line object that represents the line between p1 and p2. More...
	QLine (int x1, int y1, int x2, int y2)
	Constructs a line object that represents the line between (x1, y1) and (x2, y2). More...
void	setLine (int x1, int y1, int x2, int y2)
	Sets this line to the start in x1, y1 and end in x2, y2. More...
void	setP1 (const QPoint &p1)
	Sets the starting point of this line to p1. More...
void	setP2 (const QPoint &p2)
	Sets the end point of this line to p2. More...
void	setPoints (const QPoint &p1, const QPoint &p2)
	Sets the start point of this line to p1 and the end point of this line to p2. More...
void	translate (const QPoint &p)
	Translates this line by the given offset. More...
void	translate (int dx, int dy)
	Translates this line the distance specified by dx and dy. More...
QLine	translated (const QPoint &p) const
	Returns this line translated by the given offset. More...
QLine	translated (int dx, int dy) const
	Returns this line translated the distance specified by dx and dy. More...
int	x1 () const
	Returns the x-coordinate of the line's start point. More...
int	x2 () const
	Returns the x-coordinate of the line's end point. More...
int	y1 () const
	Returns the y-coordinate of the line's start point. More...
int	y2 () const
	Returns the y-coordinate of the line's end point. More...

Properties
QPoint	pt1
QPoint	pt2

Related Functions
(Note that these are not member functions.)
QDataStream &	operator<< (QDataStream &stream, const QLine &line)
	Writes the given line to the given stream and returns a reference to the stream. More...
QDataStream &	operator>> (QDataStream &stream, QLine &line)
	Reads a line from the given stream into the given line and returns a reference to the stream. More...

Detailed Description

The QLine class provides a two-dimensional vector using integer precision.

A QLine describes a finite length line (or a line segment) on a two-dimensional surface. The start and end points of the line are specified using integer point accuracy for coordinates. Use the QLineF constructor to retrieve a floating point copy.

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. Use isNull() to determine whether the QLine represents a valid line or a null line.

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

See also

QLineF, QPolygon, QRect

Definition at line 57 of file qline.h.

Constructors and Destructors

QLine() [1/3]

QLine::QLine ( )

inline

Constructs a null line.

Definition at line 101 of file qline.h.

Referenced by translated().

{ }

QLine() [2/3]

QLine::QLine ( const QPoint &  pt1, const QPoint &  pt2  )

inline

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

Definition at line 103 of file qline.h.

: pt1(pt1_), pt2(pt2_) { }

QLine() [3/3]

QLine::QLine ( int  x1, int  y1, int  x2, int  y2  )

inline

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

Definition at line 105 of file qline.h.

: pt1(QPoint(x1pos, y1pos)), pt2(QPoint(x2pos, y2pos)) { }

Functions

dx()

int QLine::dx ( ) const

inline

Returns the horizontal component of the line's vector.

See also

dy()

Definition at line 142 of file qline.h.

Referenced by QLineF::QLineF().

{
    return pt2.x() - pt1.x();
}

dy()

int QLine::dy ( ) const

inline

Returns the vertical component of the line's vector.

See also

dx()

Definition at line 147 of file qline.h.

Referenced by QLineF::QLineF().

{
    return pt2.y() - pt1.y();
}

isNull()

bool QLine::isNull ( ) const

inline

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

Definition at line 107 of file qline.h.

Referenced by QLineF::QLineF().

{
    return pt1 == pt2;
}

operator!=()

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

inline

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

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

Definition at line 90 of file qline.h.

{ return !(*this == d); }

operator==()

bool QLine::operator== ( const QLine &  line ) const

inline

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 195 of file qline.h.

Referenced by QLineF::QLineF().

{
    return pt1 == d.pt1 && pt2 == d.pt2;
}

p1()

QPoint QLine::p1 ( ) const

inline

Returns the line's start point.

See also

x1(), y1(), p2()

Definition at line 132 of file qline.h.

Referenced by _q_interpolate(), clipStraightLine(), QPlastiqueStyle::drawControl(), QRasterPaintEngine::drawLines(), QPlastiqueStyle::drawPrimitive(), QCleanlooksStyle::drawPrimitive(), QX11PaintEngine::drawRects(), QMatrix::map(), operator<<(), operator<<(), and QLineF::QLineF().

{
    return pt1;
}

p2()

QPoint QLine::p2 ( ) const

inline

Returns the line's end point.

See also

x2(), y2(), p1()

Definition at line 137 of file qline.h.

Referenced by _q_interpolate(), clipStraightLine(), QPlastiqueStyle::drawControl(), QRasterPaintEngine::drawLines(), QPlastiqueStyle::drawPrimitive(), QCleanlooksStyle::drawPrimitive(), QX11PaintEngine::drawRects(), QMatrix::map(), operator<<(), operator<<(), and QLineF::QLineF().

{
    return pt2;
}

setLine()

void QLine::setLine ( int  x1, int  y1, int  x2, int  y2  )

inline

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

Since

4.4

See also

setP1(), setP2(), p1(), p2()

Definition at line 189 of file qline.h.

Referenced by QLineF::QLineF().

{
    pt1 = QPoint(aX1, aY1);
    pt2 = QPoint(aX2, aY2);
}

setP1()

void QLine::setP1 ( const QPoint &  p1 )

inline

Sets the starting point of this line to p1.

Since

4.4

See also

setP2(), p1()

Definition at line 173 of file qline.h.

Referenced by QLineF::QLineF().

{
    pt1 = aP1;
}

setP2()

void QLine::setP2 ( const QPoint &  p2 )

inline

Sets the end point of this line to p2.

Since

4.4

See also

setP1(), p2()

Definition at line 178 of file qline.h.

Referenced by QLineF::QLineF().

{
    pt2 = aP2;
}

setPoints()

void QLine::setPoints ( const QPoint &  p1, const QPoint &  p2  )

inline

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

Since

4.4

See also

setP1(), setP2(), p1(), p2()

Definition at line 183 of file qline.h.

Referenced by QLineF::QLineF().

{
    pt1 = aP1;
    pt2 = aP2;
}

translate() [1/2]

void QLine::translate ( const QPoint &  p )

inline

Translates this line by the given offset.

Definition at line 152 of file qline.h.

Referenced by QLineF::QLineF(), and translate().

{
    pt1 += point;
    pt2 += point;
}

translate() [2/2]

void QLine::translate ( int  dx, int  dy  )

inline

Translates this line the distance specified by dx and dy.

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

Definition at line 158 of file qline.h.

{
    this->translate(QPoint(adx, ady));
}

translated() [1/2]

QLine QLine::translated ( const QPoint &  offset ) const

inline

Returns this line translated by the given offset.

Since

4.4

Definition at line 163 of file qline.h.

Referenced by QLineF::QLineF(), and translated().

{
    return QLine(pt1 + p, pt2 + p);
}

translated() [2/2]

QLine QLine::translated ( int  dx, int  dy  ) const

inline

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

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

Definition at line 168 of file qline.h.

{
    return translated(QPoint(adx, ady));
}

x1()

int QLine::x1 ( ) const

inline

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

See also

p1()

Definition at line 112 of file qline.h.

Referenced by QVGPaintEngine::drawLines(), QOpenGLPaintEngine::drawLines(), QPaintEngine::drawLines(), drawLines(), QTransform::map(), and QLineF::QLineF().

{
    return pt1.x();
}

x2()

int QLine::x2 ( ) const

inline

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

See also

p2()

Definition at line 122 of file qline.h.

Referenced by QVGPaintEngine::drawLines(), QOpenGLPaintEngine::drawLines(), QPaintEngine::drawLines(), drawLines(), QTransform::map(), and QLineF::QLineF().

{
    return pt2.x();
}

y1()

int QLine::y1 ( ) const

inline

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

See also

p1()

Definition at line 117 of file qline.h.

Referenced by QVGPaintEngine::drawLines(), QOpenGLPaintEngine::drawLines(), QPaintEngine::drawLines(), drawLines(), QTransform::map(), and QLineF::QLineF().

{
    return pt1.y();
}

y2()

int QLine::y2 ( ) const

inline

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

See also

p2()

Definition at line 127 of file qline.h.

Referenced by QVGPaintEngine::drawLines(), QOpenGLPaintEngine::drawLines(), QPaintEngine::drawLines(), drawLines(), QTransform::map(), and QLineF::QLineF().

{
    return pt2.y();
}

Friends and Related Functions

operator<<()

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

related

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

See also

{Serializing Qt Data Types}

Definition at line 350 of file qline.cpp.

Referenced by operator==().

{
    stream << line.p1() << line.p2();
    return stream;
}

operator>>()

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

related

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

See also

{Serializing Qt Data Types}

Definition at line 368 of file qline.cpp.

Referenced by operator==().

{
    QPoint p1, p2;
    stream >> p1;
    stream >> p2;
    line = QLine(p1, p2);

    return stream;
}

Properties

pt1

QPoint QLine::pt1

private

Definition at line 93 of file qline.h.

Referenced by dx(), dy(), isNull(), operator==(), p1(), setLine(), setP1(), setPoints(), translate(), translated(), x1(), and y1().

pt2

QPoint QLine::pt2

private

Definition at line 93 of file qline.h.

Referenced by dx(), dy(), isNull(), operator==(), p2(), setLine(), setP2(), setPoints(), translate(), translated(), x2(), and y2().

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

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