relativpositionconstraint.java

Java 3D Desktop Environment旨在使用Java 3D来创建一个3D桌面环境。功能包括：分布式的应用程序

package org.j3de.ui.constraint;

import javax.media.j3d.BoundingBox;

import javax.vecmath.Vector3d;   
import javax.vecmath.Point3d;   

import org.w3c.dom.Node;
import org.w3c.dom.Document;     
import org.w3c.dom.Element;

import org.j3de.ui.LayoutConstraint;
import org.j3de.ui.LayoutInfo;
import org.j3de.ui.UIElement;
import org.j3de.ui.WrongParameterException;
import org.j3de.util.AbstractComponent;
import org.j3de.util.StringParser;
import org.j3de.util.ConfigurationException;

public class RelativPositionConstraint extends AbstractComponent implements LayoutConstraint  {
  private LayoutInfo layoutInfo;
  private UIElement  element1;
  private UIElement  element2;

  private Vector3d   referencePoint1;
  private Vector3d   referencePoint2;
  private Vector3d   relativPosition;
 
  public void             setLayoutInfo(LayoutInfo layoutInfo) {
    this.layoutInfo = layoutInfo;
  }  

  public boolean          appliesTo(UIElement element) {
    return element.equals(element2);
  }

  private Vector3d getPosition(Vector3d referencePoint, UIElement element) {
    BoundingBox bb = new BoundingBox(layoutInfo.getBounds(element));
    Point3d upper = new Point3d();
    Point3d lower = new Point3d();

    bb.getUpper(upper);
    bb.getLower(lower);

    double x = lower.x + (upper.x - lower.x) * referencePoint.x; 
    double y = lower.y + (upper.y - lower.y) * referencePoint.y; 
    double z = lower.z + (upper.z - lower.z) * referencePoint.z; 

    return new Vector3d(x, y, z);
  }

  public void             getForce(Vector3d force) {
    Vector3d point1 = getPosition(referencePoint1,  element1);
    Vector3d point2 = getPosition(referencePoint2,  element2);
 
    Vector3d position1 = new Vector3d();
    Vector3d position2 = new Vector3d();

    layoutInfo.getPosition(element1, position1);
    layoutInfo.getPosition(element2, position2);
 
    point1.add(position1);
    point2.add(position2);

    force.set(point2);
    force.sub(point1);
    force.sub(relativPosition);
  }
  
  public boolean removeReferencesTo(UIElement element) {
    if (element1 == element) 
      return true;

    if (element2 == element) 
      return true;
    
    return false;
  }
   
  public void setParam(ConstraintParam param) throws WrongParameterException {
    if (!(param instanceof TwoElementConstraintParam))
      throw new WrongParameterException(this.getClass(), TwoElementConstraintParam.class, param.getClass());

    element1 = ((TwoElementConstraintParam)param).getElement1();
    element2 = ((TwoElementConstraintParam)param).getElement2();
  }

  public LayoutConstraint cloneConstraint() {
    RelativPositionConstraint constraint = new  RelativPositionConstraint();
    constraint.referencePoint1 = this.referencePoint1;
    constraint.referencePoint2 = this.referencePoint2;
    constraint.relativPosition = this.relativPosition;
    return constraint;
  }

  public void configure(Node node, Document nodeFactory) throws ConfigurationException {       
    super.configure(node, nodeFactory);   

    referencePoint1 = StringParser.parseVector3d(helper.getPropertyValue("referencePoint1", "0.0 0.0 0.0", true));
    referencePoint2 = StringParser.parseVector3d(helper.getPropertyValue("referencePoint2", "0.0 0.0 0.0", true));
    relativPosition = StringParser.parseVector3d(helper.getPropertyValue("relativPosition", "0.0 0.0 0.0", true));
  }

}