qt3/src/kernel/qpoint.cpp

/****************************************************************************
**
** Implementation of QPoint class
**
** Created : 931028
**
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#include "qpoint.h"
#include "qdatastream.h"


/*!
    \class QPoint qpoint.h
    \brief The QPoint class defines a point in the plane.

    \ingroup images
    \ingroup graphics
    \mainclass

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

    The coordinate type is \c QCOORD (a 32-bit integer). The minimum
    value of \c QCOORD is \c QCOORD_MIN (-2147483648) and the maximum
    value is  \c QCOORD_MAX (2147483647).

    The coordinates are accessed by the functions x() and y(); they
    can be set by setX() and setY() or by the reference functions rx()
    and ry().

    Given a point \e p, the following statements are all equivalent:
    \code
	p.setX( p.x() + 1 );
	p += QPoint( 1, 0 );
	p.rx()++;
    \endcode

    A QPoint can also be used as a vector. Addition and subtraction
    of QPoints are defined as for vectors (each component is added
    separately). You can divide or multiply a QPoint by an \c int or a
    \c double. The function manhattanLength() gives an inexpensive
    approximation of the length of the QPoint interpreted as a vector.

    Example:
    \code
	//QPoint oldPos is defined somewhere else
	MyWidget::mouseMoveEvent( QMouseEvent *e )
	{
	    QPoint vector = e->pos() - oldPos;
	    if ( vector.manhattanLength() > 3 )
	    ... //mouse has moved more than 3 pixels since oldPos
	}
    \endcode

    QPoints can be compared for equality or inequality, and they can
    be written to and read from a QStream.

    \sa QPointArray QSize, QRect
*/


/*****************************************************************************
  QPoint member functions
 *****************************************************************************/

/*!
    \fn QPoint::QPoint()

    Constructs a point with coordinates (0, 0) (isNull() returns TRUE).
*/

/*!
    \fn QPoint::QPoint( int xpos, int ypos )

    Constructs a point with x value \a xpos and y value \a ypos.
*/

/*!
    \fn bool QPoint::isNull() const

    Returns TRUE if both the x value and the y value are 0; otherwise
    returns FALSE.
*/

/*!
    \fn int QPoint::x() const

    Returns the x coordinate of the point.

    \sa setX() y()
*/

/*!
    \fn int QPoint::y() const

    Returns the y coordinate of the point.

    \sa setY() x()
*/

/*!
    \fn void QPoint::setX( int x )

    Sets the x coordinate of the point to \a x.

    \sa x() setY()
*/

/*!
    \fn void QPoint::setY( int y )

    Sets the y coordinate of the point to \a y.

    \sa y() setX()
*/


/*!
    \fn QCOORD &QPoint::rx()

    Returns a reference to the x coordinate of the point.

    Using a reference makes it possible to directly manipulate x.

    Example:
    \code
	QPoint p( 1, 2 );
	p.rx()--;         // p becomes (0, 2)
    \endcode

    \sa ry()
*/

/*!
    \fn QCOORD &QPoint::ry()

    Returns a reference to the y coordinate of the point.

    Using a reference makes it possible to directly manipulate y.

    Example:
    \code
	QPoint p( 1, 2 );
	p.ry()++;         // p becomes (1, 3)
    \endcode

    \sa rx()
*/


/*!
    \fn QPoint &QPoint::operator+=( const QPoint &p )

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

    Example:
    \code
	QPoint p(  3, 7 );
	QPoint q( -1, 4 );
	p += q;            // p becomes (2,11)
    \endcode
*/

/*!
    \fn QPoint &QPoint::operator-=( const QPoint &p )

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

    Example:
    \code
	QPoint p(  3, 7 );
	QPoint q( -1, 4 );
	p -= q;            // p becomes (4,3)
    \endcode
*/

/*!
    \fn QPoint &QPoint::operator*=( int c )

    Multiplies this point's x and y by \a c, and returns a reference
    to this point.

    Example:
    \code
	QPoint p( -1, 4 );
	p *= 2;            // p becomes (-2,8)
    \endcode
*/

/*!
    \overload QPoint &QPoint::operator*=( double c )

    Multiplies this point's x and y by \a c, and returns a reference
    to this point.

    Example:
    \code
	QPoint p( -1, 4 );
	p *= 2.5;          // p becomes (-3,10)
    \endcode

    Note that the result is truncated because points are held as
    integers.
*/


/*!
    \fn bool operator==( const QPoint &p1, const QPoint &p2 )

    \relates QPoint

    Returns TRUE if \a p1 and \a p2 are equal; otherwise returns FALSE.
*/

/*!
    \fn bool operator!=( const QPoint &p1, const QPoint &p2 )

    \relates QPoint

    Returns TRUE if \a p1 and \a p2 are not equal; otherwise returns FALSE.
*/

/*!
    \fn const QPoint operator+( const QPoint &p1, const QPoint &p2 )

    \relates QPoint

    Returns the sum of \a p1 and \a p2; each component is added separately.
*/

/*!
    \fn const QPoint operator-( const QPoint &p1, const QPoint &p2 )

    \relates QPoint

    Returns \a p2 subtracted from \a p1; each component is subtracted
    separately.
*/

/*!
    \fn const QPoint operator*( const QPoint &p, int c )

    \relates QPoint

    Returns the QPoint formed by multiplying both components of \a p
    by \a c.
*/

/*!
    \overload const QPoint operator*( int c, const QPoint &p )

    \relates QPoint

    Returns the QPoint formed by multiplying both components of \a p
    by \a c.
*/

/*!
    \overload const QPoint operator*( const QPoint &p, double c )

    \relates QPoint

    Returns the QPoint formed by multiplying both components of \a p
    by \a c.

    Note that the result is truncated because points are held as
    integers.
*/

/*!
    \overload const QPoint operator*( double c, const QPoint &p )

    \relates QPoint

    Returns the QPoint formed by multiplying both components of \a p
    by \a c.

    Note that the result is truncated because points are held as
    integers.
*/

/*!
    \overload const QPoint operator-( const QPoint &p )

    \relates QPoint

    Returns the QPoint formed by changing the sign of both components
    of \a p, equivalent to \c{QPoint(0,0) - p}.
*/

/*!
    \fn QPoint &QPoint::operator/=( int c )

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

    Example:
    \code
	QPoint p( -2, 8 );
	p /= 2;            // p becomes (-1,4)
    \endcode
*/

/*!
    \overload QPoint &QPoint::operator/=( double c )

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

    Example:
    \code
	QPoint p( -3, 10 );
	p /= 2.5;           // p becomes (-1,4)
    \endcode

    Note that the result is truncated because points are held as
    integers.
*/

/*!
    \fn const QPoint operator/( const QPoint &p, int c )

    \relates QPoint

    Returns the QPoint formed by dividing both components of \a p by
    \a c.
*/

/*!
    \overload const QPoint operator/( const QPoint &p, double c )

    \relates QPoint

    Returns the QPoint formed by dividing both components of \a p
    by \a c.

    Note that the result is truncated because points are held as
    integers.
*/


void QPoint::warningDivByZero()
{
#if defined(QT_CHECK_MATH)
    qWarning( "QPoint: Division by zero error" );
#endif
}


/*****************************************************************************
  QPoint stream functions
 *****************************************************************************/
#ifndef QT_NO_DATASTREAM
/*!
    \relates QPoint

    Writes point \a p to the stream \a s and returns a reference to
    the stream.

    \sa \link datastreamformat.html Format of the QDataStream operators \endlink
*/

QDataStream &operator<<( QDataStream &s, const QPoint &p )
{
    if ( s.version() == 1 )
	s << (Q_INT16)p.x() << (Q_INT16)p.y();
    else
	s << (Q_INT32)p.x() << (Q_INT32)p.y();
    return s;
}

/*!
    \relates QPoint

    Reads a QPoint from the stream \a s into point \a p and returns a
    reference to the stream.

    \sa \link datastreamformat.html Format of the QDataStream operators \endlink
*/

QDataStream &operator>>( QDataStream &s, QPoint &p )
{
    if ( s.version() == 1 ) {
	Q_INT16 x, y;
	s >> x;  p.rx() = x;
	s >> y;  p.ry() = y;
    }
    else {
	Q_INT32 x, y;
	s >> x;  p.rx() = x;
	s >> y;  p.ry() = y;
    }
    return s;
}
#endif // QT_NO_DATASTREAM
/*!
    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 because such
    distances apply to travelers who can only travel on a rectangular
    grid, like the streets of Manhattan.

    This is a useful, and quick to calculate, approximation to the
    true length: sqrt(pow(x(),2)+pow(y(),2)).
*/
int QPoint::manhattanLength() const
{
    return QABS(x())+QABS(y());
}