diva.canvas.connector
Class ArcConnector

java.lang.Object
  diva.canvas.AbstractFigure
      diva.canvas.connector.AbstractConnector
          diva.canvas.connector.ArcConnector

All Implemented Interfaces:

CanvasComponent, Connector, Figure, VisibleComponent, UserObjectContainer

public class ArcConnector
extends AbstractConnector

A Connector that draws itself in an arc. The connector draws itself approximately through the center of the figures that own the sites to which it is connected. The curvature of the arc can be specified in one of two ways, depending on which variable of the arc's shape remain constant as the distance between the two figures at the ends of the arc is varied:

1. Constant incident angle: The angle at which the arc connects to the figure remains constant. This is the default behaviour, and the default angle is 45 degrees.
2. Constant displacement at the maximum arc point, from the straight line drawn between the two end points of the connector. The default displacement is 20 (not for any good reason, but is has to be something...).

   Currently, only the first is supported.

   The connector uses an instance of PaintedPath to draw itself, so see that class for a more detailed description of the paint- and stroke-related methods.

   Version:

   $Id: ArcConnector.java 57046 2010-01-27 23:35:53Z cxh $

   Author:

   Edward Lee, John Reekie

   Accepted Rating:

   Red

   Field Summary

   private java.awt.geom.Arc2D	_arc The arc shape that defines the connector shape
   private double	_centerX The calculated parameters of the arc
   private double	_centerY
   protected static double	_CLOSE_THRESHOLD The threshold for when a source and a destination of an arc are considered close to one another.
   private double	_exitAngle The exit angle of the arc.
   private double	_extentAngle
   private double	_gamma The angle between the two ends of the arc.
   private ArcMidpointSite	_midpointSite The midpoint site.
   private double	_previousAngle The previous exit angle of the arc.
   private double	_radius
   private boolean	_selfloop The flag that says whether this connector is a "self-loop"
   private double	_startAngle
   private static double	MINSELFLOOPANGLE

   Constructor Summary

   ArcConnector(Site tail, Site head)
   Create a new arc connector between the given sites.

   Method Summary

   double	getAngle() Get the angle at which the arc leaves the tail figure.
   java.awt.geom.Point2D	getArcMidpoint() Return the midpoint of the arc.
   double	getGamma() Get the angle that determines the orientation of a self-loop.
   Site	getMidpointSite() Get the site that marks the midpoint of the connector.
   boolean	getSelfLoop() Get the flag saying whether this arc is to be drawn as a self-loop
   void	repositionLabel() Tell the connector to reposition its label if it has one.
   void	route() Tell the connector to route itself between the current positions of the head and tail sites.
   void	setAngle(double angle) Set the angle at which the arc leaves the tail figure, in radians.
   void	setGamma(double gamma) Set the angle that determines the orientation of a self-loop.
   void	setSelfLoop(boolean selfloop) Set the flag that says that this arc is drawn as a "self-loop."
   void	translate(double x, double y) Translate the connector.
   void	translateMidpoint(double dx, double dy) Translate the midpoint of the arc.

   Methods inherited from class diva.canvas.connector.AbstractConnector

   getBounds, getDashArray, getHeadEnd, getHeadSite, getLabelFigure, getLineWidth, getShape, getStroke, getStrokePaint, getTailEnd, getTailSite, headMoved, hit, intersects, paint, reroute, setDashArray, setHeadEnd, setHeadSite, setLabelFigure, setLineWidth, setShape, setStroke, setStrokePaint, setTailEnd, setTailSite, tailMoved, transform

   Methods inherited from class diva.canvas.AbstractFigure

   contains, getInteractor, getLayer, getOrigin, getParent, getToolTipText, getTransformContext, getUserObject, isVisible, paint, repaint, repaint, setInteractor, setParent, setToolTipText, setUserObject, setVisible

   Methods inherited from class java.lang.Object

   clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

   Methods inherited from interface diva.canvas.Figure

   contains, getInteractor, getLayer, getOrigin, getParent, getToolTipText, setInteractor, setParent, setToolTipText

   Methods inherited from interface diva.canvas.VisibleComponent

   isVisible, paint, setVisible

   Methods inherited from interface diva.canvas.CanvasComponent

   getTransformContext, repaint, repaint

   Methods inherited from interface diva.util.UserObjectContainer

   getUserObject, setUserObject

   Field Detail

   MINSELFLOOPANGLE

   private static double MINSELFLOOPANGLE

   _arc

   private java.awt.geom.Arc2D _arc

   The arc shape that defines the connector shape

   _selfloop

   private boolean _selfloop

   The flag that says whether this connector is a "self-loop"

   _exitAngle

   private double _exitAngle

   The exit angle of the arc. This is the *difference* of the angle of the line between the center of the head and tail objects, and the angle at which the arc "exits" the figure on the tail end. This parameter is used as the primary means of controlling the shape or the arc.

   _previousAngle

   private double _previousAngle

   The previous exit angle of the arc. This is used when the arc switches between a self-loop and a non-self-loop.

   _centerX

   private double _centerX

   The calculated parameters of the arc

   _centerY

   private double _centerY

   _radius

   private double _radius

   _startAngle

   private double _startAngle

   _extentAngle

   private double _extentAngle

   _gamma

   private double _gamma

   The angle between the two ends of the arc.

   _CLOSE_THRESHOLD

   protected static final double _CLOSE_THRESHOLD

   The threshold for when a source and a destination of an arc are considered close to one another. This determines how self-loops get drawn.

   See Also:

   Constant Field Values

   _midpointSite

   private ArcMidpointSite _midpointSite

   The midpoint site.

   Constructor Detail

   ArcConnector

   public ArcConnector(Site tail,
                       Site head)

   Create a new arc connector between the given sites. The connector is drawn with a width of one and in black, and at the default incident angle of 45 degrees (PI/4 radians).

   Method Detail

   getAngle

   public double getAngle()

   Get the angle at which the arc leaves the tail figure.

   getGamma

   public double getGamma()

   Get the angle that determines the orientation of a self-loop. This method should be used when saving an arc to an external representation, if the arc is a self-loop.

   getArcMidpoint

   public java.awt.geom.Point2D getArcMidpoint()

   Return the midpoint of the arc.

   Returns:

   The midpoint of the arc.

   getMidpointSite

   public Site getMidpointSite()

   Get the site that marks the midpoint of the connector.

   Returns:

   A site representing the midpoint of the arc.

   getSelfLoop

   public boolean getSelfLoop()

   Get the flag saying whether this arc is to be drawn as a self-loop

   repositionLabel

   public void repositionLabel()

   Tell the connector to reposition its label if it has one. The label is currently only positioned at the center of the arc.

   Specified by:

   repositionLabel in class AbstractConnector

   route

   public void route()

   Tell the connector to route itself between the current positions of the head and tail sites.

   Specified by:

   route in interface Connector

   Specified by:

   route in class AbstractConnector

   setAngle

   public void setAngle(double angle)

   Set the angle at which the arc leaves the tail figure, in radians. Because of the sign of the geometry, an arc with positive angle and with an arrowhead on its head will appear to be drawn counter-clockwise, and an arc with a negative angle will appear to be drawn clockwise. As a general rule, angles should be somewhat less than PI/2, and PI/4 a good general maximum figure. If the angle is outside the range -PI to PI, then it is corrected to lie within that range.

   setGamma

   public void setGamma(double gamma)

   Set the angle that determines the orientation of a self-loop. This value is roughly equal to the angle of the tangent to the loop at it's mid-point. This method is only intended for use when creating self-loop arcs from a saved representation.

   setSelfLoop

   public void setSelfLoop(boolean selfloop)

   Set the flag that says that this arc is drawn as a "self-loop." Apart from changing (slightly) the way the arc geometry is determined, this method resets some internal variables so that the arc doesn't get into a "funny state" when switching between self-loops and non-self-loops. Not, however, that this method should only be called when the arc changes, otherwise manipulation won't work properly. Use getSelfLoop() to test the current state of this flag.

   translate

   public void translate(double x,
                         double y)

   Translate the connector. This method is implemented, since controllers may wish to translate connectors when the sites at both ends are moved the same distance.

   Specified by:

   translate in interface Figure

   Specified by:

   translate in class AbstractConnector

   translateMidpoint

   public void translateMidpoint(double dx,
                                 double dy)

   Translate the midpoint of the arc. This method is not exact, but attempts to alter the shape of the arc so that the midpoint moves by something close to the given amount.