/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/* $Id$ */

package org.apache.fop.area;


// block areas hold either more block areas or line
// areas can also be used as a block spacer
// a block area may have children positioned by stacking
// or by relative to the parent for floats, tables and lists
// cacheable object
// has id information

/**
 * This is the block area class.
 * It holds child block areas such as other blocks or lines.
 */
public class Block extends BlockParent {

    private static final long serialVersionUID = 6843727817993665788L;

    /**
     * Normally stacked with other blocks.
     */
    public static final int STACK = 0;

    /**
     * Placed relative to the flow position.
     * This effects the flow placement of stacking normally.
     */
    public static final int RELATIVE = 1;

    /**
     * Relative to the block parent but not effecting the stacking
     * Used for block-container, tables and lists.
     */
    public static final int ABSOLUTE = 2;

    /**
     * Relative to a viewport/page but not effecting the stacking
     * Used for block-container.
     */
    public static final int FIXED = 3;

    private int stacking = TB;
    private int positioning = STACK;

    /** if true, allow BPD update */
    protected transient boolean allowBPDUpdate = true;

    // a block with may contain the dominant styling info in
    // terms of most lines or blocks with info

    /**
     * Add the block to this block area.
     *
     * @param block the block area to add
     */
    public void addBlock(Block block) {
        addBlock(block, true);
    }

    /**
     * Add the block to this block area.
     *
     * @param block the block area to add
     * @param autoHeight increase the height of the block.
     */
    public void addBlock(Block block, boolean autoHeight) {
        if (autoHeight && allowBPDUpdate && block.isStacked()) {
            bpd += block.getAllocBPD();
        }
        addChildArea(block);
    }

    /**
     * Add the line area to this block area.
     *
     * @param line the line area to add
     */
    public void addLineArea(LineArea line) {
        bpd += line.getAllocBPD();
        addChildArea(line);
    }

    /**
     * Set the positioning of this area.
     *
     * @param pos the positioning to use when rendering this area
     */
    public void setPositioning(int pos) {
        positioning = pos;
    }

    /**
     * Get the positioning of this area.
     *
     * @return the positioning to use when rendering this area
     */
    public int getPositioning() {
        return positioning;
    }

    /**
     * Indicates whether this block is stacked, rather than absolutely positioned.
     * @return true if it is stacked
     */
    public boolean isStacked() {
        return (getPositioning() == Block.STACK || getPositioning() == Block.RELATIVE);
    }

    /**
     * @return the start-indent trait
     */
    public int getStartIndent() {
        Integer startIndent = (Integer)getTrait(Trait.START_INDENT);
        return (startIndent != null ? startIndent : 0);
    }

}