  # QPoint Class Reference

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

`#include <qpoint.h>`

## Related Functions

(Note that these are not member functions.)
• QPoint operator+ (const QPoint & p1, const QPoint & p2)
• QPoint operator* (double c, const QPoint & p)
• QPoint operator- (const QPoint & p)
• QDataStream & operator<< (QDataStream & s, const QPoint & p)
• QPoint operator/ (const QPoint & p, int c)
• QPoint operator* (const QPoint & p, double c)
• QPoint operator* (int c, const QPoint & p)
• QDataStream & operator>> (QDataStream & s, QPoint & p)
• bool operator!= (const QPoint & p1, const QPoint & p2)
• bool operator== (const QPoint & p1, const QPoint & p2)
• QPoint operator* (const QPoint & p, int c)
• QPoint operator- (const QPoint & p1, const QPoint & p2)
• QPoint operator/ (const QPoint & p, double c)

## 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);
```

## Member Function Documentation

### QPoint::QPoint ()

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

### 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.

### int QPoint::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*= ( 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)
```

### 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)
```

### void QPoint::setX ( int x )

Sets the x coordinate of the point to x.

### void QPoint::setY ( int y )

Sets the y coordinate of the point to y.

### int QPoint::x () const

Returns the x coordinate of the point.

Examples: drawdemo/drawdemo.cpp

### int QPoint::y () const

Returns the y coordinate of the point.

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.

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