fop/src/org/apache/fop/fo/FONode.java

/*-- $Id$ -- 

 ============================================================================
                   The Apache Software License, Version 1.1
 ============================================================================
 
    Copyright (C) 1999 The Apache Software Foundation. All rights reserved.
 
 Redistribution and use in source and binary forms, with or without modifica-
 tion, are permitted provided that the following conditions are met:
 
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    this list of conditions and the following disclaimer.
 
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    this list of conditions and the following disclaimer in the documentation
    and/or other materials provided with the distribution.
 
 3. The end-user documentation included with the redistribution, if any, must
    include  the following  acknowledgment:  "This product includes  software
    developed  by the  Apache Software Foundation  (http://www.apache.org/)."
    Alternately, this  acknowledgment may  appear in the software itself,  if
    and wherever such third-party acknowledgments normally appear.
 
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 APACHE SOFTWARE  FOUNDATION  OR ITS CONTRIBUTORS  BE LIABLE FOR  ANY DIRECT,
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 This software  consists of voluntary contributions made  by many individuals
 on  behalf of the Apache Software  Foundation and was  originally created by
 James Tauber <jtauber@jtauber.com>. For more  information on the Apache 
 Software Foundation, please see <http://www.apache.org/>.
 
 */

package org.apache.fop.fo;

// FOP
import org.apache.fop.apps.FOPException;
import org.apache.fop.layout.Area;
import org.apache.fop.layout.LinkSet;

// Java
import java.util.Vector;

/**
 * base class for nodes in the formatting object tree
 */
abstract public class FONode {

    protected FObj parent;

    public Vector children = new Vector();		// made public for searching for id's

    /** value of marker before layout begins */
    public final static int START = -1000;

    /** value of marker after break-after */
    public final static int BREAK_AFTER = -1001;

    /** 
     * where the layout was up to.
     *  for FObjs it is the child number
     *  for FOText it is the character number
     */
    protected int marker = START;

    protected boolean isInTableCell = false;

    protected int forcedStartOffset = 0;
    protected int forcedWidth = 0;

    protected int widows = 0;
    protected int orphans = 0;

    protected LinkSet linkSet;

    protected FONode(FObj parent) {
	this.parent = parent;
    }

    public void setIsInTableCell() {
	this.isInTableCell = true;
	// made recursive by Eric Schaeffer
	for (int i = 0; i < this.children.size(); i++) {
	    FONode child = (FONode) this.children.elementAt(i);
	    child.setIsInTableCell();
	}
    }

    public void forceStartOffset(int offset) {
	this.forcedStartOffset = offset;
	// made recursive by Eric Schaeffer
	for (int i = 0; i < this.children.size(); i++) {
	    FONode child = (FONode) this.children.elementAt(i);
	    child.forceStartOffset(offset);
	}
    }

    public void forceWidth(int width) {
	this.forcedWidth = width;
	// made recursive by Eric Schaeffer
	for (int i = 0; i < this.children.size(); i++) {
	    FONode child = (FONode) this.children.elementAt(i);
	    child.forceWidth(width);
	}
    }

    public void resetMarker() {
	this.marker = START;
	int numChildren = this.children.size();
	for (int i = 0; i < numChildren; i++) {
	    ((FONode) children.elementAt(i)).resetMarker();
	}
    }

    public void setWidows(int wid)
    {
        widows = wid;
    }

    public void setOrphans(int orph)
    {
        orphans = orph;
    }

    public void removeAreas() {
	// still to do
    }

    protected void addChild(FONode child) {
	children.addElement(child);
    }

    public FObj getParent() {
	return this.parent;
    }

    public void setLinkSet(LinkSet linkSet) {
	this.linkSet = linkSet;        	
	for (int i = 0; i < this.children.size(); i++) {
	    FONode child = (FONode) this.children.elementAt(i);
	    child.setLinkSet(linkSet);
        }
    }

    public LinkSet getLinkSet() {
	return this.linkSet;
    }

    abstract public Status layout(Area area)
	throws FOPException;
	
    /**
    * lets outside sources access the property list
    * first used by PageNumberCitation to find the "id" property
    * returns null by default, overide this function when there is a property list
    *@param name - the name of the desired property to obtain
    * @returns the property 
    */
    public Property getProperty(String name)
    {
    	return(null);
    }

	/**
	 * At the start of a new span area layout may be partway through a
	 * nested FO, and balancing requires rollback to this known point.
	 * The snapshot records exactly where layout is at.
	 * @param snapshot a Vector of markers (Integer)
	 * @returns the updated Vector of markers (Integers)
	 */
	public Vector getMarkerSnapshot(Vector snapshot)
	{
		snapshot.addElement(new Integer(this.marker));
		
		// terminate if no kids or child not yet accessed
		if (this.marker < 0)
			return snapshot;
		else if (children.isEmpty())
			return snapshot;
		else
			return ((FONode) children.elementAt(this.marker)).getMarkerSnapshot(snapshot);
	}
	
	/**
	 * When balancing occurs, the flow layout() method restarts at the
	 * point specified by the current marker snapshot, which is retrieved
	 * and restored using this method.
	 * @param snapshot the Vector of saved markers (Integers)
	 */
	public void rollback(Vector snapshot)
	{
		this.marker = ((Integer)snapshot.elementAt(0)).intValue();
		snapshot.removeElementAt(0);

		if (this.marker == START)
		{
			// make sure all the children of this FO are also reset
			resetMarker();
			return;
		}
		else if ((this.marker == -1) || children.isEmpty())
			return;
			
		int numChildren = this.children.size();
		for (int i = this.marker + 1; i < numChildren; i++) {
			FONode fo = (FONode) children.elementAt(i);
			fo.resetMarker();
		}
		((FONode) children.elementAt(this.marker)).rollback(snapshot);
	}
}