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com.trolltech.qt.core
Class QPoint

java.lang.Object
  extended by com.trolltech.qt.QSignalEmitter
      extended by com.trolltech.qt.QtJambiObject
          extended by com.trolltech.qt.core.QPoint
All Implemented Interfaces:
QtJambiInterface

public class QPoint
extends QtJambiObject

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, QPolygon

Nested Class Summary
 
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
QSignalEmitter.AbstractSignal, QSignalEmitter.Signal0, QSignalEmitter.Signal1<A>, QSignalEmitter.Signal2<A,B>, QSignalEmitter.Signal3<A,B,C>, QSignalEmitter.Signal4<A,B,C,D>, QSignalEmitter.Signal5<A,B,C,D,E>, QSignalEmitter.Signal6<A,B,C,D,E,F>, QSignalEmitter.Signal7<A,B,C,D,E,F,G>, QSignalEmitter.Signal8<A,B,C,D,E,F,G,H>, QSignalEmitter.Signal9<A,B,C,D,E,F,G,H,I>
 
Constructor Summary
QPoint()
          Constructs a null point, i.e. with coordinates (0, 0)
QPoint(int xpos, int ypos)
          Constructs a point with the given coordinates (xpos, ypos).
 
Method Summary
 QPoint add(QPoint p)
          Adds this QPoint to p and returns the result.
 QPoint divide(double d)
          Divides this QPoint by divisor d and returns the result.
 boolean equals(java.lang.Object other)
          
static QPoint fromNativePointer(QNativePointer nativePointer)
          This function returns the QPoint instance pointed to by nativePointer
 boolean isNull()
          Returns true if both the x and y coordinates are set to 0, otherwise returns false.
 int manhattanLength()
          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.
 QPoint multiply(double d)
          Multiplies this QPoint by factor d and returns the result.
static QNativePointer nativePointerArray(QPoint[] array)
          This function returns a QNativePointer that is pointing to the specified QPoint array.
 void readFrom(QDataStream arg__1)
          Reads a QPoint from arg__1.
 void setX(int x)
          Sets the x coordinate of this point to the given x coordinate.
 void setY(int y)
          Sets the y coordinate of this point to the given y coordinate.
 QPoint subtract(QPoint p)
          Subtracts this QPoint by p and returns the result.
 void writeTo(QDataStream arg__1)
          Writes thisQPoint to arg__1.
 int x()
          Returns the x coordinate of this point.
 int y()
          Returns the y coordinate of this point.
 
Methods inherited from class com.trolltech.qt.QtJambiObject
dispose, disposed, finalize, reassignNativeResources, tr, tr, tr
 
Methods inherited from class com.trolltech.qt.QSignalEmitter
blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread
 
Methods inherited from class java.lang.Object
clone, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface com.trolltech.qt.QtJambiInterface
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership
 

Constructor Detail

QPoint

public QPoint()

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

See Also:
isNull

QPoint

public QPoint(int xpos,
              int ypos)

Constructs a point with the given coordinates (xpos, ypos).

See Also:
setX, setY
Method Detail

isNull

public final boolean isNull()

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


manhattanLength

public final int manhattanLength()

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.


writeTo

public final void writeTo(QDataStream arg__1)
Writes thisQPoint to arg__1.


readFrom

public final void readFrom(QDataStream arg__1)
Reads a QPoint from arg__1.


setX

public final void setX(int x)

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

See Also:
x, setY

setY

public final void setY(int y)

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

See Also:
y, setX

x

public final int x()

Returns the x coordinate of this point.

See Also:
setX, rx

y

public final int y()

Returns the y coordinate of this point.

See Also:
setY, ry

fromNativePointer

public static QPoint fromNativePointer(QNativePointer nativePointer)
This function returns the QPoint instance pointed to by nativePointer

Parameters:
nativePointer - the QNativePointer of which object should be returned.

nativePointerArray

public static QNativePointer nativePointerArray(QPoint[] array)
This function returns a QNativePointer that is pointing to the specified QPoint array.

Parameters:
array - the array that the returned pointer will point to.
Returns:
a QNativePointer that is pointing to the specified array.

equals

public boolean equals(java.lang.Object other)

Overrides:
equals in class java.lang.Object

multiply

public final QPoint multiply(double d)
Multiplies this QPoint by factor d and returns the result. d

Returns:

divide

public final QPoint divide(double d)
Divides this QPoint by divisor d and returns the result.


add

public final QPoint add(QPoint p)
Adds this QPoint to p and returns the result.


subtract

public final QPoint subtract(QPoint p)
Subtracts this QPoint by p and returns the result.


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