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QLine Class Reference

\inmodule QtCore\compares equality \compareswith equality QLineF \endcompareswith More...

#include <qline.h>

Collaboration diagram for QLine:

Public Member Functions

constexpr QLine ()
 Constructs a null line.
constexpr QLine (const QPoint &pt1, const QPoint &pt2)
 Constructs a line object that represents the line between p1 and p2.
constexpr QLine (int x1, int y1, int x2, int y2)
 Constructs a line object that represents the line between (x1, y1) and (x2, y2).
constexpr bool isNull () const
 Returns true if the line does not have distinct start and end points; otherwise returns false.
constexpr QPoint p1 () const
 Returns the line's start point.
constexpr QPoint p2 () const
 Returns the line's end point.
constexpr int x1 () const
 Returns the x-coordinate of the line's start point.
constexpr int y1 () const
 Returns the y-coordinate of the line's start point.
constexpr int x2 () const
 Returns the x-coordinate of the line's end point.
constexpr int y2 () const
 Returns the y-coordinate of the line's end point.
constexpr int dx () const
 Returns the horizontal component of the line's vector.
constexpr int dy () const
 Returns the vertical component of the line's vector.
constexpr void translate (const QPoint &p)
 Translates this line by the given offset.
constexpr void translate (int dx, int 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 QLine translated (const QPoint &p) const
constexpr QLine translated (int dx, int 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 QPoint center () const
void setP1 (const QPoint &p1)
void setP2 (const QPoint &p2)
void setPoints (const QPoint &p1, const QPoint &p2)
void setLine (int x1, int y1, int x2, int y2)
constexpr QLineF toLineF () const noexcept

Friends

constexpr bool comparesEqual (const QLine &lhs, const QLine &rhs) noexcept

(Note that these are not member symbols.)

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

Detailed Description

\inmodule QtCore

\compares equality \compareswith equality QLineF \endcompareswith

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.

\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. 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 18 of file qline.h.

Constructor & Destructor Documentation

◆ QLine() [1/3]

QLine::QLine ( )
inlineconstexpr

Constructs a null line.

Definition at line 74 of file qline.h.

◆ QLine() [2/3]

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

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

Definition at line 76 of file qline.h.

◆ QLine() [3/3]

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

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

Definition at line 78 of file qline.h.

Member Function Documentation

◆ center()

QPoint QLine::center ( ) const
inlinenodiscardconstexpr
Since
5.8

Returns the center point of this line. This is equivalent to (p1() + p2()) / 2, except it will never overflow.

Definition at line 146 of file qline.h.

◆ dx()

int QLine::dx ( ) const
inlineconstexpr

Returns the horizontal component of the line's vector.

See also
dy()

Definition at line 115 of file qline.h.

◆ dy()

int QLine::dy ( ) const
inlineconstexpr

Returns the vertical component of the line's vector.

See also
dx()

Definition at line 120 of file qline.h.

◆ isNull()

bool QLine::isNull ( ) const
inlineconstexpr

Returns true if the line does not have distinct start and end points; otherwise returns false.

Definition at line 80 of file qline.h.

◆ p1()

QPoint QLine::p1 ( ) const
inlineconstexpr

Returns the line's start point.

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

Definition at line 105 of file qline.h.

◆ p2()

QPoint QLine::p2 ( ) const
inlineconstexpr

Returns the line's end point.

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

Definition at line 110 of file qline.h.

◆ setLine()

void QLine::setLine ( int x1,
int y1,
int x2,
int 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 167 of file qline.h.

◆ setP1()

void QLine::setP1 ( const QPoint & p1)
inline
Since
4.4

Sets the starting point of this line to p1.

See also
setP2(), p1()

Definition at line 151 of file qline.h.

◆ setP2()

void QLine::setP2 ( const QPoint & p2)
inline
Since
4.4

Sets the end point of this line to p2.

See also
setP1(), p2()

Definition at line 156 of file qline.h.

◆ setPoints()

void QLine::setPoints ( const QPoint & p1,
const QPoint & 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 161 of file qline.h.

◆ toLineF()

QLineF QLine::toLineF ( ) const
inlinenodiscardconstexprnoexcept
Since
6.4

Returns this line as a line with floating point accuracy.

See also
QLineF::toLine()

Definition at line 385 of file qline.h.

◆ translate() [1/2]

void QLine::translate ( const QPoint & p)
inlineconstexpr

Translates this line by the given offset.

Definition at line 125 of file qline.h.

◆ translate() [2/2]

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

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 131 of file qline.h.

◆ translated() [1/2]

QLine QLine::translated ( const QPoint & offset) const
inlinenodiscardconstexpr
Since
4.4

Returns this line translated by the given offset.

Definition at line 136 of file qline.h.

◆ translated() [2/2]

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

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 141 of file qline.h.

◆ x1()

int QLine::x1 ( ) const
inlineconstexpr

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

See also
p1()

Definition at line 85 of file qline.h.

◆ x2()

int QLine::x2 ( ) const
inlineconstexpr

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

See also
p2()

Definition at line 95 of file qline.h.

◆ y1()

int QLine::y1 ( ) const
inlineconstexpr

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

See also
p1()

Definition at line 90 of file qline.h.

◆ y2()

int QLine::y2 ( ) const
inlineconstexpr

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

See also
p2()

Definition at line 100 of file qline.h.

◆ comparesEqual

bool comparesEqual ( const QLine & lhs,
const QLine & rhs )
friend

Definition at line 60 of file qline.h.

◆ 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 263 of file qline.cpp.

◆ 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 278 of file qline.cpp.

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