com.trolltech.qt.gui
Class QLineF

java.lang.Object
  extended by com.trolltech.qt.internal.QSignalEmitterInternal
      extended by com.trolltech.qt.QSignalEmitter
          extended by com.trolltech.qt.QtJambiObject
              extended by com.trolltech.qt.gui.QLineF
All Implemented Interfaces:
QtJambiInterface, java.lang.Cloneable

public class QLineF
extends QtJambiObject
implements java.lang.Cloneable

The QLineF class provides a two-dimensional vector using floating point precision. A QLineF describes a finite length line (or line segment) on a two-dimensional surface. QLineF defines the start and end points of the line using floating point accuracy for coordinates. Use the toLine() function to retrieve an integer based copy of this line.





The positions of the line's start and end points can be retrieved using the p1(), x1(), y1(), p2(), x2(), and y2() functions. The dx() and dy() functions return the horizontal and vertical components of the line, respectively.

The line's length can be retrieved using the length() function, and altered using the setLength() function. Similarly, angle() and setAngle() are respectively used for retrieving and altering the angle of the line. Use the isNull() function to determine whether the QLineF represents a valid line or a null line.

The intersect() function determines the IntersectType for this line and a given line, while the angle() function returns the angle between the lines. In addition, the unitVector() function returns a line that has the same starting point as this line, but with a length of only 1, while the normalVector() function returns a line that is perpendicular to this line with the same starting point and length.

Finally, the line can be translated a given offset using the translate() function, and can be traversed using the pointAt() function.

See also:
QLine, QPolygonF, and QRectF.


Nested Class Summary
static class QLineF.IntersectType
          Describes the intersection between two lines.
 
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
QSignalEmitter.AbstractSignal, QSignalEmitter.PrivateSignal0, QSignalEmitter.PrivateSignal1, QSignalEmitter.PrivateSignal2, QSignalEmitter.PrivateSignal3, QSignalEmitter.PrivateSignal4, QSignalEmitter.PrivateSignal5, QSignalEmitter.PrivateSignal6, QSignalEmitter.PrivateSignal7, QSignalEmitter.PrivateSignal8, QSignalEmitter.PrivateSignal9, QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9
 
Nested classes/interfaces inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal
 
Field Summary
 
Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
currentSender
 
Constructor Summary
QLineF()
          Constructs a null line.
QLineF(double x1, double y1, double x2, double y2)
          Constructs a line object that represents the line between (x1, y1) and (x2, y2).
QLineF(QLine line)
          Construct a QLineF object from the given integer-based line.
QLineF(QPointF pt1, QPointF pt2)
          Constructs a line object that represents the line between p1 and p2.
 
Method Summary
 double angle()
          Returns the angle of the line in degrees.
 double angle(QLineF l)
          Returns the angle (in degrees) between this line and the given line, taking the direction of the lines into account.
 double angleTo(QLineF l)
          Returns the angle (in degrees) from this line to the given line, taking the direction of the lines into account.
 QLineF clone()
          This method is reimplemented for internal reasons
 double dx()
          Returns the horizontal component of the line's vector.
 double dy()
          Returns the vertical component of the line's vector.
static QLineF fromPolar(double length, double angle)
          Returns a QLineF with the given length and angle.
 QLineF.IntersectType intersect(QLineF line, QPointF intersectionPoint)
          Returns a value indicating whether or not this line intersects with the given line.
 boolean isNull()
          Returns true if the line is not set up with valid start and end point; otherwise returns false.
 double length()
          Returns the length of the line.
 QLineF normalVector()
          Returns a line that is perpendicular to this line with the same starting point and length.
 QPointF p1()
          Returns the line's start point.
 QPointF p2()
          Returns the line's end point.
 QPointF pointAt(double t)
          Returns the point at the parameterized position specified by t.
 void readFrom(QDataStream arg__1)
          Reads a QLineF
 void setAngle(double angle)
          Sets the angle of the line to the given angle (in degrees).
 void setLength(double len)
          Sets the length of the line to the given length.
 void setLine(double x1, double y1, double x2, double y2)
          Sets this line to the start in x1, y1 and end in x2, y2.
 void setP1(QPointF p1)
          Sets the starting point of this line to p1.
 void setP2(QPointF p2)
          Sets the end point of this line to p2.
 void setPoints(QPointF p1, QPointF p2)
          Sets the start point of this line to p1 and the end point of this line to p2.
 QLine toLine()
          Returns an integer based copy of this line.
 java.lang.String toString()
          Returns a string representation of the this QLineF.
 void translate(double dx, double dy)
          This is an overloaded member function, provided for convenience.
 void translate(QPointF p)
          Translates this line by the given offset.
 QLineF translated(double dx, double dy)
          This is an overloaded member function, provided for convenience.
 QLineF translated(QPointF p)
          Returns this line translated by the given offset.
 QLineF unitVector()
          Returns the unit vector for this line, i.
 void writeTo(QDataStream arg__1)
          Writes thisQLineF
 double x1()
          Returns the x-coordinate of the line's start point.
 double x2()
          Returns the x-coordinate of the line's end point.
 double y1()
          Returns the y-coordinate of the line's start point.
 double y2()
          Returns the y-coordinate of the line's end point.
 
Methods inherited from class com.trolltech.qt.QtJambiObject
dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr
 
Methods inherited from class com.trolltech.qt.QSignalEmitter
blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread
 
Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
__qt_signalInitialization
 
Methods inherited from class java.lang.Object
getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface com.trolltech.qt.QtJambiInterface
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership
 

Constructor Detail

QLineF

public QLineF()
Constructs a null line.


QLineF

public QLineF(QLine line)
Construct a QLineF object from the given integer-based line.

See also:
toLine().


QLineF

public QLineF(QPointF pt1,
              QPointF pt2)
Constructs a line object that represents the line between p1 and p2.


QLineF

public QLineF(double x1,
              double y1,
              double x2,
              double y2)
Constructs a line object that represents the line between (x1, y1) and (x2, y2).

Method Detail

angle

public final double angle()
Returns the angle of the line in degrees.

Positive values for the angles mean counter-clockwise while negative values mean the clockwise direction. Zero degrees is at the 3 o'clock position.

See also:
setAngle().


angle

public final double angle(QLineF l)
Returns the angle (in degrees) between this line and the given line, taking the direction of the lines into account. If the lines do not intersect within their range, it is the intersection point of the extended lines that serves as origin (see QLineF::UnboundedIntersection ).




When the lines are parallel, this function returns 0 if they have the same direction; otherwise it returns 180.

See also:
intersect().


angleTo

public final double angleTo(QLineF l)
Returns the angle (in degrees) from this line to the given line, taking the direction of the lines into account. If the lines do not intersect within their range, it is the intersection point of the extended lines that serves as origin (see QLineF::UnboundedIntersection ).

The returned value represents the number of degrees you need to add to this line to make it have the same angle as the given line, going counter-clockwise.

See also:
intersect().


dx

public final double dx()
Returns the horizontal component of the line's vector.

See also:
dy(), and pointAt().


dy

public final double dy()
Returns the vertical component of the line's vector.

See also:
dx(), and pointAt().


isNull

public final boolean isNull()
Returns true if the line is not set up with valid start and end point; otherwise returns false.


length

public final double length()
Returns the length of the line.

See also:
setLength().


normalVector

public final QLineF normalVector()
Returns a line that is perpendicular to this line with the same starting point and length.

See also:
unitVector().


writeTo

public final void writeTo(QDataStream arg__1)
Writes thisQLineF


readFrom

public final void readFrom(QDataStream arg__1)
Reads a QLineF


p1

public final QPointF p1()
Returns the line's start point.

See also:
setP1(), x1(), y1(), and p2().


p2

public final QPointF p2()
Returns the line's end point.

See also:
setP2(), x2(), y2(), and p1().


pointAt

public final QPointF pointAt(double t)
Returns the point at the parameterized position specified by t. The function returns the line's start point if t = 0, and its end point if t = 1.

See also:
dx(), and dy().


setAngle

public final void setAngle(double angle)
Sets the angle of the line to the given angle (in degrees). This will change the position of the second point of the line such that the line has the given angle.

Positive values for the angles mean counter-clockwise while negative values mean the clockwise direction. Zero degrees is at the 3 o'clock position.

See also:
angle().


setLength

public final void setLength(double len)
Sets the length of the line to the given length. QLineF will move the end point - p2() - of the line to give the line its new length.

If the line is a null line, the length will remain zero regardless of the length specified.

See also:
length(), and isNull().


setLine

public final void setLine(double x1,
                          double y1,
                          double x2,
                          double y2)
Sets this line to the start in x1, y1 and end in x2, y2.

See also:
setP1(), setP2(), p1(), and p2().


setP1

public final void setP1(QPointF p1)
Sets the starting point of this line to p1.

See also:
setP2(), and p1().


setP2

public final void setP2(QPointF p2)
Sets the end point of this line to p2.

See also:
setP1(), and p2().


setPoints

public final void setPoints(QPointF p1,
                            QPointF p2)
Sets the start point of this line to p1 and the end point of this line to p2.

See also:
setP1(), setP2(), p1(), and p2().


toLine

public final QLine toLine()
Returns an integer based copy of this line.

Note that the returned line's start and end points are rounded to the nearest integer.

See also:
QLineF().


translate

public final void translate(QPointF p)
Translates this line by the given offset.


translate

public final void translate(double dx,
                            double dy)
This is an overloaded member function, provided for convenience.

Translates this line the distance specified by dx and dy.


translated

public final QLineF translated(QPointF p)
Returns this line translated by the given offset.


translated

public final QLineF translated(double dx,
                               double dy)
This is an overloaded member function, provided for convenience.

Returns this line translated the distance specified by dx and dy.


unitVector

public final QLineF unitVector()
Returns the unit vector for this line, i. a line starting at the same point as this line with a length of 1.0.

See also:
normalVector().


x1

public final double x1()
Returns the x-coordinate of the line's start point.

See also:
p1().


x2

public final double x2()
Returns the x-coordinate of the line's end point.

See also:
p2().


y1

public final double y1()
Returns the y-coordinate of the line's start point.

See also:
p1().


y2

public final double y2()
Returns the y-coordinate of the line's end point.

See also:
p2().


fromPolar

public static QLineF fromPolar(double length,
                               double angle)
Returns a QLineF with the given length and angle.

The first point of the line will be on the origin.

Positive values for the angles mean counter-clockwise while negative values mean the clockwise direction. Zero degrees is at the 3 o'clock position.


intersect

public final QLineF.IntersectType intersect(QLineF line,
                                            QPointF intersectionPoint)
Returns a value indicating whether or not this line intersects with the given line.

The actual intersection point is extracted to intersectionPoint (if the pointer is valid). If the lines are parallel, the intersection point is undefined.


toString

public java.lang.String toString()
Returns a string representation of the this QLineF.

Overrides:
toString in class java.lang.Object

clone

public QLineF clone()
This method is reimplemented for internal reasons

Overrides:
clone in class java.lang.Object