Help in understanding the MouseRotate Source code.(Source code attached)

Question

Hi
I am trying to understand the code here in the class below. The description says MouseTranslate is a Java3D behavior object that lets users control the
translation (X, Y) of an object via a mouse drag motion with the third mouse button (alt-click on PC). See MouseRotate for similar usage info I was able to locate the isAltDown() and isMetaDown conditions. But could not figure out where is the condition (evt.getButton() == MouseEvent.Button1) is being checked.
I have spent too much time on this, any help is greatly appreciated.
Thanking you
Venkat
package com.sun.j3d.utils.behaviors.mouse;
* MouseTranslate is a Java3D behavior object that lets users control the
* translation (X, Y) of an object via a mouse drag motion with the third
* mouse button (alt-click on PC). See MouseRotate for similar usage info.
public class MouseTranslate extends MouseBehavior {
    double x_factor = .02;
    double y_factor = .02;
    Vector3d translation = new Vector3d();
    private MouseBehaviorCallback callback = null;
     * Creates a mouse translate behavior given the transform group.
     * @param transformGroup The transformGroup to operate on.
    public MouseTranslate(TransformGroup transformGroup) {
     super(transformGroup);
     * Creates a default translate behavior.
    public MouseTranslate(){
     super(0);
     * Creates a translate behavior.
     * Note that this behavior still needs a transform
     * group to work on (use setTransformGroup(tg)) and
     * the transform group must add this behavior.
     * @param flags
    public MouseTranslate(int flags) {
     super(flags);
     * Creates a translate behavior that uses AWT listeners and behavior
     * posts rather than WakeupOnAWTEvent.  The behavior is added to the
     * specified Component. A null component can be passed to specify
     * the behavior should use listeners.  Components can then be added
     * to the behavior with the addListener(Component c) method.
     * @param c The Component to add the MouseListener
     * and MouseMotionListener to.
     * @since Java 3D 1.2.1
    public MouseTranslate(Component c) {
     super(c, 0);
     * Creates a translate behavior that uses AWT listeners and behavior
     * posts rather than WakeupOnAWTEvent.  The behaviors is added to
     * the specified Component and works on the given TransformGroup.
     * A null component can be passed to specify the behavior should use
     * listeners.  Components can then be added to the behavior with the
     * addListener(Component c) method.
     * @param c The Component to add the MouseListener and
     * MouseMotionListener to.
     * @param transformGroup The TransformGroup to operate on.
     * @since Java 3D 1.2.1
    public MouseTranslate(Component c, TransformGroup transformGroup) {
     super(c, transformGroup);
     * Creates a translate behavior that uses AWT listeners and behavior
     * posts rather than WakeupOnAWTEvent.  The behavior is added to the
     * specified Component.  A null component can be passed to specify
     * the behavior should use listeners.  Components can then be added to
     * the behavior with the addListener(Component c) method.
     * Note that this behavior still needs a transform
     * group to work on (use setTransformGroup(tg)) and the transform
     * group must add this behavior.
     * @param flags interesting flags (wakeup conditions).
     * @since Java 3D 1.2.1
    public MouseTranslate(Component c, int flags) {
     super(c, flags);
    }Rest of the code follows in the next post

Answer 1

    public void initialize() {
     super.initialize();
     if ((flags & INVERT_INPUT) == INVERT_INPUT) {
         invert = true;
         x_factor *= -1;
         y_factor *= -1;
     * Return the x-axis movement multipler.
    public double getXFactor() {
     return x_factor;
     * Return the y-axis movement multipler.
    public double getYFactor() {
     return y_factor;
     * Set the x-axis amd y-axis movement multipler with factor.
    public void setFactor( double factor) {
     x_factor = y_factor = factor;
     * Set the x-axis amd y-axis movement multipler with xFactor and yFactor
     * respectively.
    public void setFactor( double xFactor, double yFactor) {
     x_factor = xFactor;
     y_factor = yFactor;   
    public void processStimulus (Enumeration criteria) {
     WakeupCriterion wakeup;
     AWTEvent[] events;
     MouseEvent evt;
//      int id;
//      int dx, dy;
     while (criteria.hasMoreElements()) {
         wakeup = (WakeupCriterion) criteria.nextElement();
         if (wakeup instanceof WakeupOnAWTEvent) {
          events = ((WakeupOnAWTEvent)wakeup).getAWTEvent();
          if (events.length > 0) {
              evt = (MouseEvent) events[events.length-1];
              doProcess(evt);
         else if (wakeup instanceof WakeupOnBehaviorPost) {
          while (true) {
              // access to the queue must be synchronized
              synchronized (mouseq) {
               if (mouseq.isEmpty()) break;
               evt = (MouseEvent)mouseq.remove(0);
               // consolodate MOUSE_DRAG events
               while ((evt.getID() == MouseEvent.MOUSE_DRAGGED) &&
                      !mouseq.isEmpty() &&
                      (((MouseEvent)mouseq.get(0)).getID() ==
                    MouseEvent.MOUSE_DRAGGED)) {
                   evt = (MouseEvent)mouseq.remove(0);
              doProcess(evt);
     wakeupOn(mouseCriterion);
    void doProcess(MouseEvent evt) {
     int id;
     int dx, dy;
     processMouseEvent(evt);
     if (((buttonPress)&&((flags & MANUAL_WAKEUP) == 0)) ||
         ((wakeUp)&&((flags & MANUAL_WAKEUP) != 0))){
         id = evt.getID();
*         if ((id == MouseEvent.MOUSE_DRAGGED) && !evt.isAltDown() && evt.isMetaDown()) { *
          x = evt.getX();
          y = evt.getY();
          dx = x - x_last;
          dy = y - y_last;
          if ((!reset) && ((Math.abs(dy) < 50) && (Math.abs(dx) < 50))) {
              //System.out.println("dx " + dx + " dy " + dy);
              transformGroup.getTransform(currXform);
              translation.x = dx*x_factor;
              translation.y = -dy*y_factor;
              transformX.set(translation);
              if (invert) {
               currXform.mul(currXform, transformX);
              } else {
               currXform.mul(transformX, currXform);
              transformGroup.setTransform(currXform);
              transformChanged( currXform );
              if (callback!=null)
               callback.transformChanged( MouseBehaviorCallback.TRANSLATE,
                                 currXform );
          else {
              reset = false;
          x_last = x;
          y_last = y;
         else if (id == MouseEvent.MOUSE_PRESSED) {
          x_last = evt.getX();
          y_last = evt.getY();
     * Users can overload this method  which is called every time
     * the Behavior updates the transform
     * Default implementation does nothing
    public void transformChanged( Transform3D transform ) {
     * The transformChanged method in the callback class will
     * be called every time the transform is updated
    public void setupCallback( MouseBehaviorCallback callback ) {
     this.callback = callback;
}