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QPoint Class Reference


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

#include <qpoint.h>

List of all member functions.

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 int). The minimum value of QCOORD is QCOORD_MIN (-2147483648) and the maximum value is QCOORD_MAX (2147483647).

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: drawlines/connect.cpp xform/xform.cpp drawdemo/drawdemo.cpp forever/forever.cpp


Member Function Documentation

QPoint::QPoint()

Constructs a point (0,0) (a null point).

QPoint::QPoint(intxpos, intypos)

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

boolQPoint::isNull()const

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

intQPoint::manhattanLength()const

Returns the sum of the absolute values of x() and y(), traditionally known as the "Manhattan length" of the vector from the origin to the point. The tradition arises since such distances apply to travelers who can only travel on a rectangular grid, like the streets of Manhattan.

This is a useful approximation to the true length, sqrt(pow(x(),2)+pow(y(),2)).

QPoint&QPoint::operator*=(doublec)

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*=(intc)

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+=(constQPoint&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-=(constQPoint&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/=(doublec)

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/=(intc)

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().

voidQPoint::setX(intx)

Sets the x coordinate of the point to x.

See also: setY().

voidQPoint::setY(inty)

Sets the y coordinate of the point to y.

See also: setX().

intQPoint::x()const

Returns the x coordinate of the point.

See also: y().

Examples: drawdemo/drawdemo.cpp

intQPoint::y()const

Returns the y coordinate of the point.

See also: x().

Examples: drawdemo/drawdemo.cpp


Related Functions

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

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

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.

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

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

Serialization format: [x (Q_INT32), y (Q_INT32)].

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)

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.

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

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

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

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

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

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

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

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

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

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

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.


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Qt version 2.0.2