Qt logo

QPoint Class Reference


The QPoint class defines a point in the plane. More...

#include <qpoint.h>

List of all member functions.

Public Members

Static Public Members

Related Functions

(Note that these are not member functions.)

Detailed Description

The QPoint class defines a point in the plane.

A point is specified by an x coordinate and a y coordinate.

The coordinate type is QCOORD (defined in qwindowdefs.h as short). The minimum value of QCOORD is QCOORD_MIN (-32768) and the maximum value is QCOORD_MAX (32767).

We have defined many operator functions that make arithmetic on points simple and intuitive.

Example: 

    QPoint p(  1, 2 );
    QPoint q( -8, 5 );
    QPoint r(  9, 7 );
    QPoint x = 2*p + (q-r)*5.5 - (r+p/1.5);

See also: QSize and QRect.

Examples: tictac/tictac.cpp table/table.cpp forever/forever.cpp connect/connect.cpp drawdemo/drawdemo.cpp xform/xform.cpp aclock/aclock.cpp

Member Function Documentation

QPoint::QPoint ()

Constructs a point with undefined x and y values.

QPoint::QPoint ( int xpos, int ypos )

Constructs a point with the x value xpos and y value ypos.

bool QPoint::isNull () const

Returns TRUE if both the x value and the y value are 0.

QPoint & QPoint::operator*= ( double c )

Multiplies both x and y with c, and return a reference to this point.

Example: 

    QPoint p( -1, 4 );
    p *= 2.5;                   // p becomes (-3,10)

Note that the result is truncated.

QPoint & QPoint::operator*= ( int c )

Multiplies both x and y with c, and return a reference to this point.

Example: 

    QPoint p( -1, 4 );
    p *= 2;                     // p becomes (-2,8)

QPoint & QPoint::operator+= ( const QPoint & p )

Adds p to the point and returns a reference to this point.

Example: 

    QPoint p(  3, 7 );
    QPoint q( -1, 4 );
    p += q;                     // p becomes (2,11)

QPoint & QPoint::operator-= ( const QPoint & p )

Subtracts p from the point and returns a reference to this point.

Example: 

    QPoint p(  3, 7 );
    QPoint q( -1, 4 );
    p -= q;                     // p becomes (4,3)

QPoint & QPoint::operator/= ( double c )

Divides both x and y by c, and return a reference to this point.

Example: 

    QPoint p( -3, 10 );
    p /= 2.5;                   // p becomes (-1,4)

Note that the result is truncated.

QPoint & QPoint::operator/= ( int c )

Divides both x and y by c, and return a reference to this point.

Example: 

    QPoint p( -2, 8 );
    p /= 2;                     // p becomes (-1,4)

QCOORD & QPoint::rx ()

Returns a reference to the x coordinate of the point.

Using a reference makes it possible to directly manipulate x.

Example: 

    QPoint p( 1, 2 );
    p.rx()--;                   // p becomes (0,2)

See also: ry().

QCOORD & QPoint::ry ()

Returns a reference to the y coordinate of the point.

Using a reference makes it possible to directly manipulate y.

Example: 

    QPoint p( 1, 2 );
    p.ry()++;                   // p becomes (1,3)

See also: rx().

void QPoint::setX ( int x )

Sets the x coordinate of the point to x.

See also: setY().

void QPoint::setY ( int y )

Sets the y coordinate of the point to y.

See also: setX().

int QPoint::x () const

Returns the x coordinate of the point.

See also: y().

Examples: table/table.cpp drawdemo/drawdemo.cpp aclock/aclock.cpp

int QPoint::y () const

Returns the y coordinate of the point.

See also: x().

Examples: table/table.cpp drawdemo/drawdemo.cpp aclock/aclock.cpp

Related Functions

bool operator== (const QPoint & p1, const QPoint & p2)

Returns TRUE if p1 and p2 are equal, or FALSE if they are different.

bool operator!= (const QPoint & p1, const QPoint & p2)

Returns TRUE if p1 and p2 are different, or FALSE if they are equal.

QPoint operator+ (const QPoint & p1, const QPoint & p2)

Returns the sum of p1 and p2; each component is added separately.

QPoint operator- (const QPoint & p1, const QPoint & p2)

Returns p2 subtracted from p1; each component is subtracted separately.

QPoint operator* (const QPoint & p, int c)

Multiplies both of p's components by c and returns the result.

QPoint operator* (int c, const QPoint & p)

Multiplies both of p's components by c and returns the result.

QPoint operator* (const QPoint & p, double c)

Multiplies both of p's components by c and returns the result.

QPoint operator* (double c, const QPoint & p)

Multiplies both of p's components by c and returns the result.

QPoint operator- (const QPoint & p)

Returns p where x and y have opposite signs.

QPoint operator/ (const QPoint & p, int c)

Divides both of p's components by c and returns the result.

QPoint operator/ (const QPoint & p, double c)

Divides both of p's components by c and returns the result.

Note that the result is truncated.

QDataStream & operator<< (QDataStream & s, const QPoint & p)

Writes a QPoint to the stream and returns a reference to the stream.

Serialization format: [x (INT16), y (INT16)].

QDataStream & operator>> (QDataStream & s, QPoint & p)

Reads a QPoint from the stream and returns a reference to the stream.

Search the documentation, FAQ, qt-interest archive and more (uses www.troll.no):

This file is part of the Qt toolkit, copyright © 1995-98 Troll Tech, all rights reserved.

It was generated from the following files:

Copyright © 1998 Troll TechTrademarks
Qt version 1.42