/*
 * @(#)TableView.java	1.42 10/03/23
 *
 * Copyright (c) 2006, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
package javax.swing.text.html;

import java.awt.*;
import java.util.BitSet;
import java.util.Vector;
import java.util.Arrays;
import javax.swing.SizeRequirements;
import javax.swing.event.DocumentEvent;

import javax.swing.text.*;

/**
 * HTML table view.  
 * 
 * @author  Timothy Prinzing
 * @version 1.42 03/23/10
 * @see     View
 */
/*public*/ class TableView extends BoxView implements ViewFactory {

    /**
     * Constructs a TableView for the given element.
     *
     * @param elem the element that this view is responsible for
     */
    public TableView(Element elem) {
	super(elem, View.Y_AXIS);
	rows = new Vector();
	gridValid = false;
	captionIndex = -1;
        totalColumnRequirements = new SizeRequirements();
    }

    /**
     * Creates a new table row.
     *
     * @param elem an element
     * @return the row
     */
    protected RowView createTableRow(Element elem) {
	// PENDING(prinz) need to add support for some of the other
	// elements, but for now just ignore anything that is not
	// a TR.
	Object o = elem.getAttributes().getAttribute(StyleConstants.NameAttribute);
	if (o == HTML.Tag.TR) {
	    return new RowView(elem);
	}
	return null;
    }

    /**
     * The number of columns in the table.
     */
    public int getColumnCount() {
	return columnSpans.length;
    }

    /**
     * Fetches the span (width) of the given column.  
     * This is used by the nested cells to query the 
     * sizes of grid locations outside of themselves.
     */
    public int getColumnSpan(int col) {
	if (col < columnSpans.length) {
	    return columnSpans[col];
	}
	return 0;
    }

    /**
     * The number of rows in the table.
     */
    public int getRowCount() {
	return rows.size();
    }

    /**
     * Fetch the span of multiple rows.  This includes
     * the border area.
     */
    public int getMultiRowSpan(int row0, int row1) {
	RowView rv0 = getRow(row0);
	RowView rv1 = getRow(row1);
	if ((rv0 != null) && (rv1 != null)) {
	    int index0 = rv0.viewIndex;
	    int index1 = rv1.viewIndex;
	    int span = getOffset(Y_AXIS, index1) - getOffset(Y_AXIS, index0) + 
		getSpan(Y_AXIS, index1);
	    return span;
	}
	return 0;
    }

    /**
     * Fetches the span (height) of the given row.
     */
    public int getRowSpan(int row) {
	RowView rv = getRow(row);
	if (rv != null) {
	    return getSpan(Y_AXIS, rv.viewIndex);
	}
	return 0;
    }

    RowView getRow(int row) {
	if (row < rows.size()) {
	    return (RowView) rows.elementAt(row);
	}
	return null;
    }

    protected View getViewAtPoint(int x, int y, Rectangle alloc) {
	int n = getViewCount();
	View v = null;
	Rectangle allocation = new Rectangle();
	for (int i = 0; i < n; i++) {
	    allocation.setBounds(alloc);
	    childAllocation(i, allocation);
	    v = getView(i);
	    if (v instanceof RowView) {
		v = ((RowView)v).findViewAtPoint(x, y, allocation);
		if (v != null) {
		    alloc.setBounds(allocation);
		    return v;
		}
	    }
	}
        return super.getViewAtPoint(x, y, alloc);
    }

    /**
     * Determines the number of columns occupied by
     * the table cell represented by given element.
     */
    protected int getColumnsOccupied(View v) {
	AttributeSet a = v.getElement().getAttributes();

        if (a.isDefined(HTML.Attribute.COLSPAN)) {
            String s = (String) a.getAttribute(HTML.Attribute.COLSPAN);
            if (s != null) {
                try {
                    return Integer.parseInt(s);
                } catch (NumberFormatException nfe) {
                    // fall through to one column
                }
            }
        }

	return 1;
    }

    /**
     * Determines the number of rows occupied by
     * the table cell represented by given element.
     */
    protected int getRowsOccupied(View v) {
	AttributeSet a = v.getElement().getAttributes();

        if (a.isDefined(HTML.Attribute.ROWSPAN)) {
            String s = (String) a.getAttribute(HTML.Attribute.ROWSPAN);
            if (s != null) {
                try {
                    return Integer.parseInt(s);
                } catch (NumberFormatException nfe) {
                    // fall through to one row
                }
            }
        }

	return 1;
    }

    protected void invalidateGrid() {
	gridValid = false;
    }

    protected StyleSheet getStyleSheet() {
	HTMLDocument doc = (HTMLDocument) getDocument();
	return doc.getStyleSheet();
    }

    /**
     * Update the insets, which contain the caption if there
     * is a caption.
     */
    void updateInsets() {
	short top = (short) painter.getInset(TOP, this);
	short bottom = (short) painter.getInset(BOTTOM, this);
	if (captionIndex != -1) {
	    View caption = getView(captionIndex);
	    short h = (short) caption.getPreferredSpan(Y_AXIS);
	    AttributeSet a = caption.getAttributes();
	    Object align = a.getAttribute(CSS.Attribute.CAPTION_SIDE);
	    if ((align != null) && (align.equals("bottom"))) {
		bottom += h;
	    } else {
		top += h;
	    }
	}
	setInsets(top, (short) painter.getInset(LEFT, this), 
		  bottom, (short) painter.getInset(RIGHT, this));
    }

    /**
     * Update any cached values that come from attributes.
     */
    protected void setPropertiesFromAttributes() {
	StyleSheet sheet = getStyleSheet();
	attr = sheet.getViewAttributes(this);
	painter = sheet.getBoxPainter(attr);
	if (attr != null) {
	    setInsets((short) painter.getInset(TOP, this), 
		      (short) painter.getInset(LEFT, this), 
			  (short) painter.getInset(BOTTOM, this), 
		      (short) painter.getInset(RIGHT, this));

	    CSS.LengthValue lv = (CSS.LengthValue) 
		attr.getAttribute(CSS.Attribute.BORDER_SPACING);
	    if (lv != null) {
		cellSpacing = (int) lv.getValue();
	    } else {
		cellSpacing = 0;
	    }
	    lv = (CSS.LengthValue)                                
		    attr.getAttribute(CSS.Attribute.BORDER_TOP_WIDTH);
	    if (lv != null) {                                     
		    borderWidth = (int) lv.getValue();                
	    } else {                                              
		    borderWidth = 0;                                  
	    }                                                     

		}
    }

    /**
     * Fill in the grid locations that are placeholders
     * for multi-column, multi-row, and missing grid
     * locations.
     */
    void updateGrid() {
	if (! gridValid) {
	    relativeCells = false;
	    multiRowCells = false;

	    // determine which views are table rows and clear out
	    // grid points marked filled.
	    captionIndex = -1;
	    rows.removeAllElements();
	    int n = getViewCount();
	    for (int i = 0; i < n; i++) {
		View v = getView(i);
		if (v instanceof RowView) {
		    rows.addElement(v);
		    RowView rv = (RowView) v;
		    rv.clearFilledColumns();
		    rv.rowIndex = rows.size() - 1;
		    rv.viewIndex = i;
		} else {
		    Object o = v.getElement().getAttributes().getAttribute(StyleConstants.NameAttribute);
		    if (o instanceof HTML.Tag) {
			HTML.Tag kind = (HTML.Tag) o;
			if (kind == HTML.Tag.CAPTION) {
			    captionIndex = i;
			}
		    }
		}
	    }

	    int maxColumns = 0;
	    int nrows = rows.size();
	    for (int row = 0; row < nrows; row++) {
		RowView rv = getRow(row);
		int col = 0;
		for (int cell = 0; cell < rv.getViewCount(); cell++, col++) {
		    View cv = rv.getView(cell);
		    if (! relativeCells) {
			AttributeSet a = cv.getAttributes();
			CSS.LengthValue lv = (CSS.LengthValue) 
			    a.getAttribute(CSS.Attribute.WIDTH);
			if ((lv != null) && (lv.isPercentage())) {
			    relativeCells = true;
			}
		    }
		    // advance to a free column
		    for (; rv.isFilled(col); col++);
		    int rowSpan = getRowsOccupied(cv);
		    if (rowSpan > 1) {
			multiRowCells = true;
		    }
		    int colSpan = getColumnsOccupied(cv);
		    if ((colSpan > 1) || (rowSpan > 1)) {
			// fill in the overflow entries for this cell
			int rowLimit = row + rowSpan;
			int colLimit = col + colSpan;
			for (int i = row; i < rowLimit; i++) {
			    for (int j = col; j < colLimit; j++) {
				if (i != row || j != col) {
				    addFill(i, j);
				}
			    }
			}
			if (colSpan > 1) {
			    col += colSpan - 1;
			}
		    }
		}
		maxColumns = Math.max(maxColumns, col);
	    }

	    // setup the column layout/requirements
	    columnSpans = new int[maxColumns];
	    columnOffsets = new int[maxColumns];
	    columnRequirements = new SizeRequirements[maxColumns];
	    for (int i = 0; i < maxColumns; i++) {
		columnRequirements[i] = new SizeRequirements();
                columnRequirements[i].maximum = Integer.MAX_VALUE;
	    }
	    gridValid = true;
	}
    }

    /**
     * Mark a grid location as filled in for a cells overflow.
     */
    void addFill(int row, int col) {
	RowView rv = getRow(row);
	if (rv != null) {
	    rv.fillColumn(col);
	}
    }

    /**
     * Layout the columns to fit within the given target span.
     *
     * @param targetSpan the given span for total of all the table
     *  columns
     * @param reqs the requirements desired for each column.  This
     *  is the column maximum of the cells minimum, preferred, and
     *  maximum requested span
     * @param spans the return value of how much to allocated to
     *  each column
     * @param offsets the return value of the offset from the
     *  origin for each column
     * @return the offset from the origin and the span for each column 
     *  in the offsets and spans parameters
     */
    protected void layoutColumns(int targetSpan, int[] offsets, int[] spans, 
				 SizeRequirements[] reqs) {
        //clean offsets and spans
        Arrays.fill(offsets, 0);
        Arrays.fill(spans, 0);
	colIterator.setLayoutArrays(offsets, spans, targetSpan);
	CSS.calculateTiledLayout(colIterator, targetSpan);
    }

    /**
     * Calculate the requirements for each column.  The calculation
     * is done as two passes over the table.  The table cells that
     * occupy a single column are scanned first to determine the
     * maximum of minimum, preferred, and maximum spans along the
     * give axis.  Table cells that span multiple columns are excluded
     * from the first pass.  A second pass is made to determine if
     * the cells that span multiple columns are satisfied.  If the
     * column requirements are not satisified, the needs of the 
     * multi-column cell is mixed into the existing column requirements.
     * The calculation of the multi-column distribution is based upon
     * the proportions of the existing column requirements and taking
     * into consideration any constraining maximums.
     */
    void calculateColumnRequirements(int axis) {
        // clean columnRequirements
        for (SizeRequirements req : columnRequirements) {
            req.minimum = 0;
            req.preferred = 0;
            req.maximum = Integer.MAX_VALUE;
        }
	Container host = getContainer();
	if (host != null) {
	    if (host instanceof JTextComponent) {
		skipComments = !((JTextComponent)host).isEditable();
	    } else {
		skipComments = true;
	    }
	}
	// pass 1 - single column cells
	boolean hasMultiColumn = false;
	int nrows = getRowCount();
	for (int i = 0; i < nrows; i++) {
	    RowView row = getRow(i);
	    int col = 0;
	    int ncells = row.getViewCount();
	    for (int cell = 0; cell < ncells; cell++) {
		View cv = row.getView(cell);
		if (skipComments && !(cv instanceof CellView)) {
		    continue;
		}
		for (; row.isFilled(col); col++); // advance to a free column
		int rowSpan = getRowsOccupied(cv);
		int colSpan = getColumnsOccupied(cv);
		if (colSpan == 1) {
		    checkSingleColumnCell(axis, col, cv);
		} else {
		    hasMultiColumn = true;
		    col += colSpan - 1;
		}
		col++;
	    }
	}

	// pass 2 - multi-column cells
	if (hasMultiColumn) {
	    for (int i = 0; i < nrows; i++) {
		RowView row = getRow(i);
		int col = 0;
		int ncells = row.getViewCount();
		for (int cell = 0; cell < ncells; cell++) {
		    View cv = row.getView(cell);
		    if (skipComments && !(cv instanceof CellView)) {
			continue;
		    }
		    for (; row.isFilled(col); col++); // advance to a free column
		    int colSpan = getColumnsOccupied(cv);
		    if (colSpan > 1) {
			checkMultiColumnCell(axis, col, colSpan, cv);
			col += colSpan - 1;
		    }
		    col++;
		}
	    }
	}
    }

    /**
     * check the requirements of a table cell that spans a single column.
     */
    void checkSingleColumnCell(int axis, int col, View v) {
	SizeRequirements req = columnRequirements[col];
	req.minimum = Math.max((int) v.getMinimumSpan(axis), req.minimum);
	req.preferred = Math.max((int) v.getPreferredSpan(axis), req.preferred);
    }

    /**
     * check the requirements of a table cell that spans multiple
     * columns.
     */
    void checkMultiColumnCell(int axis, int col, int ncols, View v) {
	// calculate the totals
	long min = 0;
	long pref = 0;
	long max = 0;
	for (int i = 0; i < ncols; i++) {
	    SizeRequirements req = columnRequirements[col + i];
	    min += req.minimum;
	    pref += req.preferred;
	    max += req.maximum;
	}

	// check if the minimum size needs adjustment.
	int cmin = (int) v.getMinimumSpan(axis); 
	if (cmin > min) {
	    /*
	     * the columns that this cell spans need adjustment to fit
	     * this table cell.... calculate the adjustments.
	     */
	    SizeRequirements[] reqs = new SizeRequirements[ncols];
	    for (int i = 0; i < ncols; i++) {
		reqs[i] = columnRequirements[col + i];
	    }
	    int[] spans = new int[ncols];
	    int[] offsets = new int[ncols];
	    SizeRequirements.calculateTiledPositions(cmin, null, reqs, 
						     offsets, spans);
	    // apply the adjustments
	    for (int i = 0; i < ncols; i++) {
		SizeRequirements req = reqs[i];
		req.minimum = Math.max(spans[i], req.minimum);
		req.preferred = Math.max(req.minimum, req.preferred);
		req.maximum = Math.max(req.preferred, req.maximum);
	    }
	}

	// check if the preferred size needs adjustment.
	int cpref = (int) v.getPreferredSpan(axis); 
	if (cpref > pref) {
	    /*
	     * the columns that this cell spans need adjustment to fit
	     * this table cell.... calculate the adjustments.
	     */
	    SizeRequirements[] reqs = new SizeRequirements[ncols];
	    for (int i = 0; i < ncols; i++) {
		reqs[i] = columnRequirements[col + i];
	    }
	    int[] spans = new int[ncols];
	    int[] offsets = new int[ncols];
	    SizeRequirements.calculateTiledPositions(cpref, null, reqs, 
						     offsets, spans);
	    // apply the adjustments
	    for (int i = 0; i < ncols; i++) {
		SizeRequirements req = reqs[i];
		req.preferred = Math.max(spans[i], req.preferred);
		req.maximum = Math.max(req.preferred, req.maximum);
	    }
	}

    }

    // --- BoxView methods -----------------------------------------

    /**
     * Calculate the requirements for the minor axis.  This is called by
     * the superclass whenever the requirements need to be updated (i.e.
     * a preferenceChanged was messaged through this view).  
     * <p>
     * This is implemented to calculate the requirements as the sum of the 
     * requirements of the columns and then adjust it if the 
     * CSS width or height attribute is specified and applicable to
     * the axis.
     */
    protected SizeRequirements calculateMinorAxisRequirements(int axis, SizeRequirements r) {
	updateGrid();
	
	// calculate column requirements for each column
	calculateColumnRequirements(axis);


	// the requirements are the sum of the columns.
	if (r == null) {
	    r = new SizeRequirements();
	}
	long min = 0;
	long pref = 0;
	int n = columnRequirements.length;
	for (int i = 0; i < n; i++) {
	    SizeRequirements req = columnRequirements[i];
	    min += req.minimum;
	    pref += req.preferred;
	}
	int adjust = (n + 1) * cellSpacing + 2 * borderWidth;
	min += adjust;
	pref += adjust;
	r.minimum = (int) min;
	r.preferred = (int) pref;
	r.maximum = (int) pref;


	AttributeSet attr = getAttributes();
        CSS.LengthValue cssWidth = (CSS.LengthValue)attr.getAttribute(
                                                    CSS.Attribute.WIDTH);

	if (BlockView.spanSetFromAttributes(axis, r, cssWidth, null)) {
            if (r.minimum < (int)min) {
                // The user has requested a smaller size than is needed to
                // show the table, override it.
                r.maximum = r.minimum = r.preferred = (int) min;
            }
        }
        totalColumnRequirements.minimum = r.minimum;
        totalColumnRequirements.preferred = r.preferred;
        totalColumnRequirements.maximum = r.maximum;

	// set the alignment
	Object o = attr.getAttribute(CSS.Attribute.TEXT_ALIGN);
	if (o != null) {
	    // set horizontal alignment
	    String ta = o.toString();
	    if (ta.equals("left")) {
		r.alignment = 0;
	    } else if (ta.equals("center")) {
		r.alignment = 0.5f;
	    } else if (ta.equals("right")) {
		r.alignment = 1;
	    } else {
		r.alignment = 0;
	    }
	} else {
	    r.alignment = 0;
	}
	
	return r;
    }

    /**
     * Calculate the requirements for the major axis.  This is called by
     * the superclass whenever the requirements need to be updated (i.e.
     * a preferenceChanged was messaged through this view).  
     * <p>
     * This is implemented to provide the superclass behavior adjusted for
     * multi-row table cells.
     */
    protected SizeRequirements calculateMajorAxisRequirements(int axis, SizeRequirements r) {
	updateInsets();
	rowIterator.updateAdjustments();
	r = CSS.calculateTiledRequirements(rowIterator, r);
	r.maximum = r.preferred;
	return r;
    }

    /**
     * Perform layout for the minor axis of the box (i.e. the
     * axis orthoginal to the axis that it represents).  The results 
     * of the layout should be placed in the given arrays which represent 
     * the allocations to the children along the minor axis.  This 
     * is called by the superclass whenever the layout needs to be 
     * updated along the minor axis.
     * <p>
     * This is implemented to call the 
     * <a href="#layoutColumns">layoutColumns</a> method, and then
     * forward to the superclass to actually carry out the layout
     * of the tables rows.
     *
     * @param targetSpan the total span given to the view, which
     *  whould be used to layout the children
     * @param axis the axis being layed out
     * @param offsets the offsets from the origin of the view for
     *  each of the child views.  This is a return value and is
     *  filled in by the implementation of this method
     * @param spans the span of each child view;  this is a return
     *  value and is filled in by the implementation of this method
     * @return the offset and span for each child view in the
     *  offsets and spans parameters
     */
    protected void layoutMinorAxis(int targetSpan, int axis, int[] offsets, int[] spans) {
	// make grid is properly represented
	updateGrid();

	// all of the row layouts are invalid, so mark them that way
	int n = getRowCount();
	for (int i = 0; i < n; i++) {
	    RowView row = getRow(i);
	    row.layoutChanged(axis);
	}

	// calculate column spans
	layoutColumns(targetSpan, columnOffsets, columnSpans, columnRequirements);

	// continue normal layout
	super.layoutMinorAxis(targetSpan, axis, offsets, spans);
    }


    /**
     * Perform layout for the major axis of the box (i.e. the
     * axis that it represents).  The results 
     * of the layout should be placed in the given arrays which represent 
     * the allocations to the children along the minor axis.  This 
     * is called by the superclass whenever the layout needs to be 
     * updated along the minor axis.
     * <p>
     * This method is where the layout of the table rows within the
     * table takes place.  This method is implemented to call the use 
     * the RowIterator and the CSS collapsing tile to layout 
     * with border spacing and border collapsing capabilities.
     *
     * @param targetSpan the total span given to the view, which
     *  whould be used to layout the children
     * @param axis the axis being layed out
     * @param offsets the offsets from the origin of the view for
     *  each of the child views; this is a return value and is
     *  filled in by the implementation of this method
     * @param spans the span of each child view; this is a return
     *  value and is filled in by the implementation of this method
     * @return the offset and span for each child view in the
     *  offsets and spans parameters
     */
    protected void layoutMajorAxis(int targetSpan, int axis, int[] offsets, int[] spans) {
	rowIterator.setLayoutArrays(offsets, spans);
	CSS.calculateTiledLayout(rowIterator, targetSpan);

	if (captionIndex != -1) {
	    // place the caption
	    View caption = getView(captionIndex);
	    int h = (int) caption.getPreferredSpan(Y_AXIS);
	    spans[captionIndex] = h;
	    short boxBottom = (short) painter.getInset(BOTTOM, this);
	    if (boxBottom != getBottomInset()) {
		offsets[captionIndex] = targetSpan + boxBottom;
	    } else {
		offsets[captionIndex] = - getTopInset();
	    }
	}
    }

    /**
     * Fetches the child view that represents the given position in
     * the model.  This is implemented to walk through the children
     * looking for a range that contains the given position.  In this
     * view the children do not necessarily have a one to one mapping 
     * with the child elements.
     *
     * @param pos  the search position >= 0
     * @param a  the allocation to the table on entry, and the
     *   allocation of the view containing the position on exit
     * @return  the view representing the given position, or 
     *   null if there isn't one
     */
    protected View getViewAtPosition(int pos, Rectangle a) {
        int n = getViewCount();
        for (int i = 0; i < n; i++) {
            View v = getView(i);
            int p0 = v.getStartOffset();
            int p1 = v.getEndOffset();
            if ((pos >= p0) && (pos < p1)) {
                // it's in this view.
		if (a != null) {
		    childAllocation(i, a);
		}
                return v;
            }
        }
	if (pos == getEndOffset()) {
	    View v = getView(n - 1);
	    if (a != null) {
		this.childAllocation(n - 1, a);
	    }
	    return v;
	}
        return null;
    }

    // --- View methods ---------------------------------------------

    /**
     * Fetches the attributes to use when rendering.  This is
     * implemented to multiplex the attributes specified in the
     * model with a StyleSheet.
     */
    public AttributeSet getAttributes() {
	if (attr == null) {
	    StyleSheet sheet = getStyleSheet();
	    attr = sheet.getViewAttributes(this);
	}
	return attr;
    }

    /**
     * Renders using the given rendering surface and area on that
     * surface.  This is implemented to delegate to the css box
     * painter to paint the border and background prior to the 
     * interior.  The superclass culls rendering the children
     * that don't directly intersect the clip and the row may
     * have cells hanging from a row above in it.  The table
     * does not use the superclass rendering behavior and instead
     * paints all of the rows and lets the rows cull those 
     * cells not intersecting the clip region.
     *
     * @param g the rendering surface to use
     * @param allocation the allocated region to render into
     * @see View#paint
     */
    public void paint(Graphics g, Shape allocation) {
	// paint the border 
	Rectangle a = allocation.getBounds();
	setSize(a.width, a.height);
	if (captionIndex != -1) {
	    // adjust the border for the caption
	    short top = (short) painter.getInset(TOP, this);
	    short bottom = (short) painter.getInset(BOTTOM, this);
	    if (top != getTopInset()) {
		int h = getTopInset() - top;
		a.y += h;
		a.height -= h;
	    } else {
		a.height -= getBottomInset() - bottom;
	    }
	}
        painter.paint(g, a.x, a.y, a.width, a.height, this); 
	// paint interior
	int n = getViewCount();
	for (int i = 0; i < n; i++) {
	    View v = getView(i);
	    v.paint(g, getChildAllocation(i, allocation));
	}
	//super.paint(g, a);
    }

    /**
     * Establishes the parent view for this view.  This is
     * guaranteed to be called before any other methods if the
     * parent view is functioning properly.
     * <p> 
     * This is implemented
     * to forward to the superclass as well as call the
     * <a href="#setPropertiesFromAttributes">setPropertiesFromAttributes</a>
     * method to set the paragraph properties from the css
     * attributes.  The call is made at this time to ensure
     * the ability to resolve upward through the parents 
     * view attributes.
     *
     * @param parent the new parent, or null if the view is
     *  being removed from a parent it was previously added
     *  to
     */
    public void setParent(View parent) {
	super.setParent(parent);
        if (parent != null) {
	    setPropertiesFromAttributes();
        }
    }

    /**
     * Fetches the ViewFactory implementation that is feeding
     * the view hierarchy.  
     * This replaces the ViewFactory with an implementation that
     * calls through to the createTableRow and createTableCell
     * methods.   If the element given to the factory isn't a
     * table row or cell, the request is delegated to the factory
     * produced by the superclass behavior.
     *
     * @return the factory, null if none
     */
    public ViewFactory getViewFactory() {
	return this;
    }

    /**
     * Gives notification that something was inserted into 
     * the document in a location that this view is responsible for. 
     * This replaces the ViewFactory with an implementation that
     * calls through to the createTableRow and createTableCell
     * methods.   If the element given to the factory isn't a
     * table row or cell, the request is delegated to the factory
     * passed as an argument.
     *
     * @param e the change information from the associated document
     * @param a the current allocation of the view
     * @param f the factory to use to rebuild if the view has children
     * @see View#insertUpdate
     */
    public void insertUpdate(DocumentEvent e, Shape a, ViewFactory f) {
	super.insertUpdate(e, a, this);
    }

    /**
     * Gives notification that something was removed from the document
     * in a location that this view is responsible for.
     * This replaces the ViewFactory with an implementation that
     * calls through to the createTableRow and createTableCell
     * methods.   If the element given to the factory isn't a
     * table row or cell, the request is delegated to the factory
     * passed as an argument.
     *
     * @param e the change information from the associated document
     * @param a the current allocation of the view
     * @param f the factory to use to rebuild if the view has children
     * @see View#removeUpdate
     */
    public void removeUpdate(DocumentEvent e, Shape a, ViewFactory f) {
	super.removeUpdate(e, a, this);
    }

    /**
     * Gives notification from the document that attributes were changed
     * in a location that this view is responsible for.
     * This replaces the ViewFactory with an implementation that
     * calls through to the createTableRow and createTableCell
     * methods.   If the element given to the factory isn't a
     * table row or cell, the request is delegated to the factory
     * passed as an argument.
     *
     * @param e the change information from the associated document
     * @param a the current allocation of the view
     * @param f the factory to use to rebuild if the view has children
     * @see View#changedUpdate
     */
    public void changedUpdate(DocumentEvent e, Shape a, ViewFactory f) {
	super.changedUpdate(e, a, this);
    }

    protected void forwardUpdate(DocumentEvent.ElementChange ec, 
				 DocumentEvent e, Shape a, ViewFactory f) {
	super.forwardUpdate(ec, e, a, f);
	// A change in any of the table cells usually effects the whole table,
	// so redraw it all!
	if (a != null) {
	    Component c = getContainer();
	    if (c != null) {
		Rectangle alloc = (a instanceof Rectangle) ? (Rectangle)a :
		                   a.getBounds();
		c.repaint(alloc.x, alloc.y, alloc.width, alloc.height);
	    }
	}
    }

    /**
     * Change the child views.  This is implemented to
     * provide the superclass behavior and invalidate the
     * grid so that rows and columns will be recalculated.
     */
    public void replace(int offset, int length, View[] views) {
	super.replace(offset, length, views);
	invalidateGrid();
    }

    // --- ViewFactory methods ------------------------------------------

    /**
     * The table itself acts as a factory for the various 
     * views that actually represent pieces of the table.
     * All other factory activity is delegated to the factory
     * returned by the parent of the table.
     */
    public View create(Element elem) {
	Object o = elem.getAttributes().getAttribute(StyleConstants.NameAttribute);
	if (o instanceof HTML.Tag) {
	    HTML.Tag kind = (HTML.Tag) o;
	    if (kind == HTML.Tag.TR) {
		return createTableRow(elem);
	    } else if ((kind == HTML.Tag.TD) || (kind == HTML.Tag.TH)) {
		return new CellView(elem);
	    } else if (kind == HTML.Tag.CAPTION) {
		return new javax.swing.text.html.ParagraphView(elem);
	    }
	}
	// default is to delegate to the normal factory
	View p = getParent();
	if (p != null) {
	    ViewFactory f = p.getViewFactory();
	    if (f != null) {
		return f.create(elem);
	    }
	}
	return null;
    }
	
    // ---- variables ----------------------------------------------------

    private AttributeSet attr;
    private StyleSheet.BoxPainter painter;

    private int cellSpacing;
    private int borderWidth;

    /**
     * The index of the caption view if there is a caption.
     * This has a value of -1 if there is no caption.  The
     * caption lives in the inset area of the table, and is
     * updated with each time the grid is recalculated.
     */
    private int captionIndex;

    /**
     * Do any of the table cells contain a relative size
     * specification?  This is updated with each call to
     * updateGrid().  If this is true, the ColumnIterator
     * will do extra work to calculate relative cell 
     * specifications.
     */
    private boolean relativeCells;

    /**
     * Do any of the table cells span multiple rows?  If
     * true, the RowRequirementIterator will do additional
     * work to adjust the requirements of rows spanned by
     * a single table cell.  This is updated with each call to
     * updateGrid().
     */
    private boolean multiRowCells;

    int[] columnSpans;
    int[] columnOffsets;
    /**
     * SizeRequirements for all the columns.
     */
    SizeRequirements totalColumnRequirements;
    SizeRequirements[] columnRequirements;

    RowIterator rowIterator = new RowIterator();
    ColumnIterator colIterator = new ColumnIterator();

    Vector rows;

    // whether to display comments inside table or not.
    boolean skipComments = false;

    boolean gridValid;
    static final private BitSet EMPTY = new BitSet();

    class ColumnIterator implements CSS.LayoutIterator {

	/**
	 * Disable percentage adjustments which should only apply
	 * when calculating layout, not requirements.
	 */
	void disablePercentages() {
	    percentages = null;
	}

	/**
	 * Update percentage adjustments if they are needed.
	 */
	private void updatePercentagesAndAdjustmentWeights(int span) {
	    adjustmentWeights = new int[columnRequirements.length];
	    for (int i = 0; i < columnRequirements.length; i++) {
		adjustmentWeights[i] = 0;
	    }
	    if (relativeCells) {
		percentages = new int[columnRequirements.length];
	    } else {
		percentages = null;
	    }
	    int nrows = getRowCount();
	    for (int rowIndex = 0; rowIndex < nrows; rowIndex++) {
		RowView row = getRow(rowIndex);
		int col = 0;
		int ncells = row.getViewCount();
		for (int cell = 0; cell < ncells; cell++, col++) {
		    View cv = row.getView(cell);
		    for (; row.isFilled(col); col++); // advance to a free column
		    int rowSpan = getRowsOccupied(cv);
		    int colSpan = getColumnsOccupied(cv);
		    AttributeSet a = cv.getAttributes();
		    CSS.LengthValue lv = (CSS.LengthValue) 
			a.getAttribute(CSS.Attribute.WIDTH);
		    if ( lv != null ) {
			int len = (int) (lv.getValue(span) / colSpan + 0.5f);
			for (int i = 0; i < colSpan; i++) {
			    if (lv.isPercentage()) {
				// add a percentage requirement
				percentages[col+i] = Math.max(percentages[col+i], len);
                                adjustmentWeights[col + i] = Math.max(adjustmentWeights[col + i], WorstAdjustmentWeight);
			    } else {
                                adjustmentWeights[col + i] = Math.max(adjustmentWeights[col + i], WorstAdjustmentWeight - 1);
			    }
			}
		    }
		    col += colSpan - 1;
		}
	    }
	} 

	/**
	 * Set the layout arrays to use for holding layout results
	 */
	public void setLayoutArrays(int offsets[], int spans[], int targetSpan) {
	    this.offsets = offsets;
	    this.spans = spans;
	    updatePercentagesAndAdjustmentWeights(targetSpan);
	}

	// --- RequirementIterator methods -------------------

	public int getCount() {
	    return columnRequirements.length;
	}

	public void setIndex(int i) {
	    col = i;
	}

	public void setOffset(int offs) {
	    offsets[col] = offs;
	}

	public int getOffset() {
	    return offsets[col];
	}

	public void setSpan(int span) {
	    spans[col] = span;
	}

	public int getSpan() {
	    return spans[col];
	}

	public float getMinimumSpan(float parentSpan) {
	    // do not care for percentages, since min span can't 
            // be less than columnRequirements[col].minimum,
	    // but can be less than percentage value.
	    return columnRequirements[col].minimum;
	}

	public float getPreferredSpan(float parentSpan) {
	    if ((percentages != null) && (percentages[col] != 0)) {
                return Math.max(percentages[col], columnRequirements[col].minimum);
	    }
	    return columnRequirements[col].preferred;
	}

	public float getMaximumSpan(float parentSpan) {
	    return columnRequirements[col].maximum;
	}

	public float getBorderWidth() {
	    return borderWidth;        
	}                              


	public float getLeadingCollapseSpan() {
	    return cellSpacing;
	}

	public float getTrailingCollapseSpan() {
	    return cellSpacing;
	}

	public int getAdjustmentWeight() {
	    return adjustmentWeights[col];
	}

	/**
	 * Current column index
	 */
	private int col;

	/**
	 * percentage values (may be null since there
	 * might not be any).
	 */
	private int[] percentages;

	private int[] adjustmentWeights;

	private int[] offsets;
	private int[] spans;
    }

    class RowIterator implements CSS.LayoutIterator {

	RowIterator() {
	}

	void updateAdjustments() {
	    int axis = Y_AXIS;
	    if (multiRowCells) {
		// adjust requirements of multi-row cells
		int n = getRowCount();
		adjustments = new int[n];
		for (int i = 0; i < n; i++) {
		    RowView rv = getRow(i);
		    if (rv.multiRowCells == true) {
			int ncells = rv.getViewCount();
			for (int j = 0; j < ncells; j++) {
			    View v = rv.getView(j);
			    int nrows = getRowsOccupied(v);
			    if (nrows > 1) {
				int spanNeeded = (int) v.getPreferredSpan(axis);
				adjustMultiRowSpan(spanNeeded, nrows, i);
			    }
			}
		    }
		}
	    } else {
		adjustments = null;
	    }
	}

	/**
	 * Fixup preferences to accomodate a multi-row table cell
	 * if not already covered by existing preferences.  This is
	 * a no-op if not all of the rows needed (to do this check/fixup)
	 * have arrived yet.
	 */
	void adjustMultiRowSpan(int spanNeeded, int nrows, int rowIndex) {
	    if ((rowIndex + nrows) > getCount()) {
		// rows are missing (could be a bad rowspan specification)
		// or not all the rows have arrived.  Do the best we can with
		// the current set of rows.
		nrows = getCount() - rowIndex;
		if (nrows < 1) {
		    return;
		}
	    }
	    int span = 0;
	    for (int i = 0; i < nrows; i++) {
		RowView rv = getRow(rowIndex + i);
		span += rv.getPreferredSpan(Y_AXIS);
	    }
	    if (spanNeeded > span) {
		int adjust = (spanNeeded - span);
		int rowAdjust = adjust / nrows;
		int firstAdjust = rowAdjust + (adjust - (rowAdjust * nrows));
		RowView rv = getRow(rowIndex);
                adjustments[rowIndex] = Math.max(adjustments[rowIndex],
                                                 firstAdjust);
		for (int i = 1; i < nrows; i++) {
                    adjustments[rowIndex + i] = Math.max(
                        adjustments[rowIndex + i], rowAdjust);
		}
	    }
	}

	void setLayoutArrays(int[] offsets, int[] spans) {
	    this.offsets = offsets;
	    this.spans = spans;
	}

	// --- RequirementIterator methods -------------------

	public void setOffset(int offs) {
	    RowView rv = getRow(row);
	    if (rv != null) {
		offsets[rv.viewIndex] = offs;
	    }
	}

	public int getOffset() {
	    RowView rv = getRow(row);
	    if (rv != null) {
		return offsets[rv.viewIndex];
	    }
	    return 0;
	}

	public void setSpan(int span) {
	    RowView rv = getRow(row);
	    if (rv != null) {
		spans[rv.viewIndex] = span;
	    }
	}

	public int getSpan() {
	    RowView rv = getRow(row);
	    if (rv != null) {
		return spans[rv.viewIndex];
	    }
	    return 0;
	}

	public int getCount() {
	    return rows.size();
	}

	public void setIndex(int i) {
	    row = i;
	}

	public float getMinimumSpan(float parentSpan) {
	    return getPreferredSpan(parentSpan);
	}

	public float getPreferredSpan(float parentSpan) {
	    RowView rv = getRow(row);
	    if (rv != null) {
		int adjust = (adjustments != null) ? adjustments[row] : 0;
		return rv.getPreferredSpan(TableView.this.getAxis()) + adjust;
	    }
	    return 0;
	}

	public float getMaximumSpan(float parentSpan) {
	    return getPreferredSpan(parentSpan);
	}

	public float getBorderWidth() {
	    return borderWidth;        
	}                              

	public float getLeadingCollapseSpan() {
	    return cellSpacing;
	}

	public float getTrailingCollapseSpan() {
	    return cellSpacing;
	}

	public int getAdjustmentWeight() {
	    return 0;
	}

	/**
	 * Current row index
	 */
	private int row;

	/**
	 * Adjustments to the row requirements to handle multi-row
	 * table cells.  
	 */
	private int[] adjustments;

	private int[] offsets;
	private int[] spans;
    }

    /**
     * View of a row in a row-centric table.
     */
    public class RowView extends BoxView {

	/**
	 * Constructs a TableView for the given element.
	 *
	 * @param elem the element that this view is responsible for
	 */
        public RowView(Element elem) {
	    super(elem, View.X_AXIS);
	    fillColumns = new BitSet();
	    RowView.this.setPropertiesFromAttributes();
	}

	void clearFilledColumns() {
	    fillColumns.and(EMPTY);
	}

	void fillColumn(int col) {
	    fillColumns.set(col);
	}

	boolean isFilled(int col) {
	    return fillColumns.get(col);
	}

	/**
	 * The number of columns present in this row.
	 */
	int getColumnCount() {
	    int nfill = 0;
	    int n = fillColumns.size();
	    for (int i = 0; i < n; i++) {
		if (fillColumns.get(i)) {
		    nfill ++;
		}
	    }
	    return getViewCount() + nfill;
	}

	/**
	 * Fetches the attributes to use when rendering.  This is
	 * implemented to multiplex the attributes specified in the
	 * model with a StyleSheet.
	 */
        public AttributeSet getAttributes() {
	    return attr;
	}

	View findViewAtPoint(int x, int y, Rectangle alloc) {
	    int n = getViewCount();
	    for (int i = 0; i < n; i++) {
		if (getChildAllocation(i, alloc).contains(x, y)) {
		    childAllocation(i, alloc);
		    return getView(i);
		}
	    }
	    return null;
	}

        protected StyleSheet getStyleSheet() {
	    HTMLDocument doc = (HTMLDocument) getDocument();
	    return doc.getStyleSheet();
	}

	/**
	 * This is called by a child to indicate its 
	 * preferred span has changed.  This is implemented to
	 * execute the superclass behavior and well as try to
	 * determine if a row with a multi-row cell hangs across
	 * this row.  If a multi-row cell covers this row it also
	 * needs to propagate a preferenceChanged so that it will
	 * recalculate the multi-row cell.
	 *
	 * @param child the child view
	 * @param width true if the width preference should change
	 * @param height true if the height preference should change
	 */
        public void preferenceChanged(View child, boolean width, boolean height) {
	    super.preferenceChanged(child, width, height);
	    if (TableView.this.multiRowCells && height) {
		for (int i = rowIndex  - 1; i >= 0; i--) {
		    RowView rv = TableView.this.getRow(i);
		    if (rv.multiRowCells) {
			rv.preferenceChanged(null, false, true);
			break;
		    }
		}
	    }
	}

        // The major axis requirements for a row are dictated by the column
        // requirements. These methods use the value calculated by
        // TableView.
        protected SizeRequirements calculateMajorAxisRequirements(int axis, SizeRequirements r) {
            SizeRequirements req = new SizeRequirements();
            req.minimum = totalColumnRequirements.minimum;
            req.maximum = totalColumnRequirements.maximum;
            req.preferred = totalColumnRequirements.preferred;
            req.alignment = 0f;
            return req;
        }

        public float getMinimumSpan(int axis) {
            float value;

            if (axis == View.X_AXIS) {
                value = totalColumnRequirements.minimum + getLeftInset() +
                        getRightInset();
            }
            else {
                value = super.getMinimumSpan(axis);
            }
            return value;
        }

        public float getMaximumSpan(int axis) {
            float value;

            if (axis == View.X_AXIS) {
                // We're flexible.
                value = (float)Integer.MAX_VALUE;
            }
            else {
                value = super.getMaximumSpan(axis);
            }
            return value;
        }

        public float getPreferredSpan(int axis) {
            float value;

            if (axis == View.X_AXIS) {
                value = totalColumnRequirements.preferred + getLeftInset() +
                        getRightInset();
            }
            else {
                value = super.getPreferredSpan(axis);
            }
            return value;
        }

	public void changedUpdate(DocumentEvent e, Shape a, ViewFactory f) {
	    super.changedUpdate(e, a, f);
	    int pos = e.getOffset();
	    if (pos <= getStartOffset() && (pos + e.getLength()) >=
		getEndOffset()) {
		RowView.this.setPropertiesFromAttributes();
	    }
	}
	
	/**
	 * Renders using the given rendering surface and area on that
	 * surface.  This is implemented to delegate to the css box
	 * painter to paint the border and background prior to the 
	 * interior.
	 *
	 * @param g the rendering surface to use
	 * @param allocation the allocated region to render into
	 * @see View#paint
	 */
	public void paint(Graphics g, Shape allocation) {
	    Rectangle a = (Rectangle) allocation;
	    painter.paint(g, a.x, a.y, a.width, a.height, this);
	    super.paint(g, a);
	}

	/**
	 * Change the child views.  This is implemented to
	 * provide the superclass behavior and invalidate the
	 * grid so that rows and columns will be recalculated.
	 */
        public void replace(int offset, int length, View[] views) {
	    super.replace(offset, length, views);
	    invalidateGrid();
	}

	/**
	 * Calculate the height requirements of the table row.  The
	 * requirements of multi-row cells are not considered for this
	 * calculation.  The table itself will check and adjust the row
	 * requirements for all the rows that have multi-row cells spanning
	 * them.  This method updates the multi-row flag that indicates that
	 * this row and rows below need additional consideration.
	 */
        protected SizeRequirements calculateMinorAxisRequirements(int axis, SizeRequirements r) {
//	    return super.calculateMinorAxisRequirements(axis, r);
	    long min = 0;
	    long pref = 0;
	    long max = 0;
	    multiRowCells = false;
	    int n = getViewCount();
	    for (int i = 0; i < n; i++) {
		View v = getView(i);
		if (getRowsOccupied(v) > 1) {
		    multiRowCells = true;
		    max = Math.max((int) v.getMaximumSpan(axis), max);
		} else {
		    min = Math.max((int) v.getMinimumSpan(axis), min);
		    pref = Math.max((int) v.getPreferredSpan(axis), pref);
		    max = Math.max((int) v.getMaximumSpan(axis), max);
		}
	    }

	    if (r == null) {
		r = new SizeRequirements();
		r.alignment = 0.5f;
	    }
	    r.preferred = (int) pref;
	    r.minimum = (int) min;
	    r.maximum = (int) max;
	    return r;
	}

	/**
	 * Perform layout for the major axis of the box (i.e. the
	 * axis that it represents).  The results of the layout should
	 * be placed in the given arrays which represent the allocations
	 * to the children along the major axis.  
	 * <p>
	 * This is re-implemented to give each child the span of the column 
	 * width for the table, and to give cells that span multiple columns 
	 * the multi-column span.
	 *
	 * @param targetSpan the total span given to the view, which
	 *  whould be used to layout the children
	 * @param axis the axis being layed out
	 * @param offsets the offsets from the origin of the view for
	 *  each of the child views; this is a return value and is
	 *  filled in by the implementation of this method
	 * @param spans the span of each child view; this is a return
	 *  value and is filled in by the implementation of this method
	 * @return the offset and span for each child view in the
	 *  offsets and spans parameters
	 */
        protected void layoutMajorAxis(int targetSpan, int axis, int[] offsets, int[] spans) {
	    int col = 0;
	    int ncells = getViewCount();
	    for (int cell = 0; cell < ncells; cell++) {
		View cv = getView(cell);
		if (skipComments && !(cv instanceof CellView)) {
		    continue;
		}
		for (; isFilled(col); col++); // advance to a free column
		int colSpan = getColumnsOccupied(cv);
		spans[cell] = columnSpans[col];
		offsets[cell] = columnOffsets[col];
		if (colSpan > 1) {
		    int n = columnSpans.length;
		    for (int j = 1; j < colSpan; j++) {
			// Because the table may be only partially formed, some
			// of the columns may not yet exist.  Therefore we check
			// the bounds.
			if ((col+j) < n) {
			    spans[cell] += columnSpans[col+j];
			    spans[cell] += cellSpacing;
			}
		    }
		    col += colSpan - 1;
		}
		col++;
	    }
	}

	/**
	 * Perform layout for the minor axis of the box (i.e. the
	 * axis orthoginal to the axis that it represents).  The results 
	 * of the layout should be placed in the given arrays which represent 
	 * the allocations to the children along the minor axis.  This 
	 * is called by the superclass whenever the layout needs to be 
	 * updated along the minor axis.
	 * <p>
	 * This is implemented to delegate to the superclass, then adjust
	 * the span for any cell that spans multiple rows.
	 *
	 * @param targetSpan the total span given to the view, which
	 *  whould be used to layout the children
	 * @param axis the axis being layed out
	 * @param offsets the offsets from the origin of the view for
	 *  each of the child views; this is a return value and is
	 *  filled in by the implementation of this method
	 * @param spans the span of each child view; this is a return
	 *  value and is filled in by the implementation of this method
	 * @return the offset and span for each child view in the
	 *  offsets and spans parameters
	 */
        protected void layoutMinorAxis(int targetSpan, int axis, int[] offsets, int[] spans) {
	    super.layoutMinorAxis(targetSpan, axis, offsets, spans);
	    int col = 0;
	    int ncells = getViewCount();
	    for (int cell = 0; cell < ncells; cell++, col++) {
		View cv = getView(cell);
		for (; isFilled(col); col++); // advance to a free column
		int colSpan = getColumnsOccupied(cv);
		int rowSpan = getRowsOccupied(cv);
		if (rowSpan > 1) {
		    
		    int row0 = rowIndex;
		    int row1 = Math.min(rowIndex + rowSpan - 1, getRowCount()-1);
		    spans[cell] = getMultiRowSpan(row0, row1);
		}
		if (colSpan > 1) {
		    col += colSpan - 1;
		}
	    }
	}

	/**
	 * Determines the resizability of the view along the
	 * given axis.  A value of 0 or less is not resizable.
	 *
	 * @param axis may be either View.X_AXIS or View.Y_AXIS
	 * @return the resize weight
	 * @exception IllegalArgumentException for an invalid axis
	 */
        public int getResizeWeight(int axis) {
	    return 1;
	}

	/**
	 * Fetches the child view that represents the given position in
	 * the model.  This is implemented to walk through the children
	 * looking for a range that contains the given position.  In this
	 * view the children do not necessarily have a one to one mapping 
	 * with the child elements.
	 *
	 * @param pos  the search position >= 0
	 * @param a  the allocation to the table on entry, and the
	 *   allocation of the view containing the position on exit
	 * @return  the view representing the given position, or 
	 *   null if there isn't one
	 */
        protected View getViewAtPosition(int pos, Rectangle a) {
	    int n = getViewCount();
	    for (int i = 0; i < n; i++) {
		View v = getView(i);
		int p0 = v.getStartOffset();
		int p1 = v.getEndOffset();
		if ((pos >= p0) && (pos < p1)) {
		    // it's in this view.
		    if (a != null) {
			childAllocation(i, a);
		    }
		    return v;
		}
	    }
	    if (pos == getEndOffset()) {
		View v = getView(n - 1);
		if (a != null) {
		    this.childAllocation(n - 1, a);
		}
		return v;
	    }
	    return null;
	}

	/**
	 * Update any cached values that come from attributes.
	 */
	void setPropertiesFromAttributes() {
	    StyleSheet sheet = getStyleSheet();
	    attr = sheet.getViewAttributes(this);
	    painter = sheet.getBoxPainter(attr);
	}

	private StyleSheet.BoxPainter painter;
        private AttributeSet attr;

	/** columns filled by multi-column or multi-row cells */
	BitSet fillColumns;

	/** 
	 * The row index within the overall grid 
	 */
	int rowIndex;

	/**
	 * The view index (for row index to view index conversion).
	 * This is set by the updateGrid method.
	 */
	int viewIndex;

	/**
	 * Does this table row have cells that span multiple rows?
	 */
	boolean multiRowCells;

    }

    /**
     * Default view of an html table cell.  This needs to be moved
     * somewhere else.
     */
    class CellView extends BlockView {

	/**
	 * Constructs a TableCell for the given element.
	 *
	 * @param elem the element that this view is responsible for
	 */
        public CellView(Element elem) {
	    super(elem, Y_AXIS);
	}

	/**
	 * Perform layout for the major axis of the box (i.e. the
	 * axis that it represents).  The results of the layout should
	 * be placed in the given arrays which represent the allocations
	 * to the children along the major axis.  This is called by the
	 * superclass to recalculate the positions of the child views
	 * when the layout might have changed.
	 * <p>
	 * This is implemented to delegate to the superclass to
	 * tile the children.  If the target span is greater than
	 * was needed, the offsets are adjusted to align the children
	 * (i.e. position according to the html valign attribute).
	 *
	 * @param targetSpan the total span given to the view, which
	 *  whould be used to layout the children
	 * @param axis the axis being layed out
	 * @param offsets the offsets from the origin of the view for
	 *  each of the child views; this is a return value and is
	 *  filled in by the implementation of this method
	 * @param spans the span of each child view; this is a return
	 *  value and is filled in by the implementation of this method
	 * @return the offset and span for each child view in the
	 *  offsets and spans parameters
	 */
        protected void layoutMajorAxis(int targetSpan, int axis, int[] offsets, int[] spans) {
	    super.layoutMajorAxis(targetSpan, axis, offsets, spans);
	    // calculate usage
	    int used = 0;
	    int n = spans.length;
	    for (int i = 0; i < n; i++) {
		used += spans[i];
	    }

	    // calculate adjustments
	    int adjust = 0;
	    if (used < targetSpan) {
		// PENDING(prinz) change to use the css alignment.
		String valign = (String) getElement().getAttributes().getAttribute(
		    HTML.Attribute.VALIGN);
		if (valign == null) {
		    AttributeSet rowAttr = getElement().getParentElement().getAttributes();
		    valign = (String) rowAttr.getAttribute(HTML.Attribute.VALIGN);
		}
		if ((valign == null) || valign.equals("middle")) {
		    adjust = (targetSpan - used) / 2;
		} else if (valign.equals("bottom")) {
		    adjust = targetSpan - used;
		}
	    }

	    // make adjustments.
	    if (adjust != 0) {
		for (int i = 0; i < n; i++) {
		    offsets[i] += adjust;
		}
	    }
	}

	/**
	 * Calculate the requirements needed along the major axis.
	 * This is called by the superclass whenever the requirements 
	 * need to be updated (i.e. a preferenceChanged was messaged 
	 * through this view).  
	 * <p>
	 * This is implemented to delegate to the superclass, but
	 * indicate the maximum size is very large (i.e. the cell 
	 * is willing to expend to occupy the full height of the row).
	 * 
	 * @param axis the axis being layed out.
	 * @param r the requirements to fill in.  If null, a new one
	 *  should be allocated.
	 */
        protected SizeRequirements calculateMajorAxisRequirements(int axis, 
								  SizeRequirements r) {
	    SizeRequirements req = super.calculateMajorAxisRequirements(axis, r);
	    req.maximum = Integer.MAX_VALUE;
	    return req;
	}

        @Override
        protected SizeRequirements calculateMinorAxisRequirements(int axis, SizeRequirements r) {
            SizeRequirements rv = super.calculateMinorAxisRequirements(axis, r);
            //for the cell the minimum should be derived from the child views 
            //the parent behaviour is to use CSS for that
            int n = getViewCount();
            int min = 0;
            for (int i = 0; i < n; i++) {
                View v = getView(i);
                min = Math.max((int) v.getMinimumSpan(axis), min);                
            }            
            rv.minimum = Math.min(rv.minimum, min);
            return rv;
        }
    }


}
