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[QtCore module]

The QPoint class defines a point in the plane using integer precision. More...

#include <QPoint>

**QPoint**()- bool
**isNull**() const - int
**manhattanLength**() const - int &
**rx**() - int &
**ry**() - void
**setX**( int*x*) - void
**setY**( int*y*) - int
**x**() const - int
**y**() const - QPoint &
**operator*=**( qreal*factor*) - QPoint &
**operator+=**( const QPoint &*point*) - QPoint &
**operator-=**( const QPoint &*point*) - QPoint &
**operator/=**( qreal*divisor*)

- const QPoint
**operator-**( const QPoint &*point*)

The QPoint class defines a point in the plane using integer precision.

A point is specified by a x coordinate and an y coordinate which can be accessed using the x() and y() functions. The isNull() function returns true if both x and y are set to 0. The coordinates can be set (or altered) using the setX() and setY() functions, or alternatively the rx() and ry() functions which return references to the coordinates (allowing direct manipulation).

Given a point *p*, the following statements are all equivalent:

QPoint p; p.setX(p.x() + 1); p += QPoint(1, 0); p.rx()++;

A QPoint object can also be used as a vector: Addition and subtraction are defined as for vectors (each component is added separately). A QPoint object can also be divided or multiplied by an `int` or a `qreal`.

In addition, the QPoint class provides the manhattanLength() function which gives an inexpensive approximation of the length of the QPoint object interpreted as a vector. Finally, QPoint objects can be streamed as well as compared.

See also QPointF and QPolygon.

Constructs a null point, i.e. with coordinates (0, 0)

See also isNull().

Constructs a point with the given coordinates (*x*, *y*).

Returns true if both the x and y coordinates are set to 0, otherwise returns false.

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. For example:

```
QPoint oldPosition;
MyWidget::mouseMoveEvent(QMouseEvent *event)
{
QPoint point = event->pos() - oldPosition;
if (point.manhattanLength() > 3)
// the mouse has moved more than 3 pixels since the oldPosition
}
```

This is a useful, and quick to calculate, approximation to the true length:

int trueManhattanLength = sqrt(pow(x(), 2) + pow(y(), 2));

The tradition of "Manhattan length" arises because such distances apply to travelers who can only travel on a rectangular grid, like the streets of Manhattan.

Returns a reference to the x coordinate of this point.

Using a reference makes it possible to directly manipulate x. For example:

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

Returns a reference to the y coordinate of this point.

Using a reference makes it possible to directly manipulate y. For example:

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

Sets the x coordinate of this point to the given *x* coordinate.

Sets the y coordinate of this point to the given *y* coordinate.

Returns the x coordinate of this point.

Returns the y coordinate of this point.

Multiplies this point's coordinates by the given *factor*, and returns a reference to this point. For example:

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

Note that the result is rounded to the nearest integer as points are held as integers. Use QPointF for floating point accuracy.

See also operator/=().

Adds the given *point* to this point and returns a reference to this point. For example:

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

See also operator-=().

Subtracts the given *point* from this point and returns a reference to this point. For example:

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

See also operator+=().

Divides both x and y by the given *divisor*, and returns a reference to this point. For example:

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

Note that the result is rounded to the nearest integer as points are held as integers. Use QPointF for floating point accuracy.

See also operator*=().

Returns true if *p1* and *p2* are not equal; otherwise returns false.

Returns a copy of the given *point* multiplied by the given *factor*.

Note that the result is rounded to the nearest integer as points are held as integers. Use QPointF for floating point accuracy.

See also QPoint::operator*=().

This is an overloaded member function, provided for convenience.

Returns a copy of the given *point* multiplied by the given *factor*.

Returns a QPoint object that is the sum of the given points, *p1* and *p2*; each component is added separately.

See also QPoint::operator+=().

Returns a QPoint object that is formed by subtracting *p2* from *p1*; each component is subtracted separately.

See also QPoint::operator-=().

This is an overloaded member function, provided for convenience.

Returns a QPoint object that is formed by changing the sign of both components of the given *point*.

Equivalent to `QPoint(0,0) - point`.

Returns the QPoint formed by dividing both components of the given *point* by the given *divisor*.

See also QPoint::operator/=().

This is an overloaded member function, provided for convenience.

Writes the given *point* to the given *stream* and returns a reference to the stream.

See also Format of the QDataStream Operators.

Returns true if *p1* and *p2* are equal; otherwise returns false.

This is an overloaded member function, provided for convenience.

Reads a point from the given *stream* into the given *point* and returns a reference to the stream.

See also Format of the QDataStream Operators.

Copyright © 2008 Trolltech | Trademarks | Qt 4.3.5 |