fop/fop-core/src/main/java/org/apache/fop/render/rtf/rtflib/rtfdoc/RtfSpaceManager.java

/*
 * 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.render.rtf.rtflib.rtfdoc;

import java.util.LinkedList;

/**
 * This class is responsible for saving space-before/space-after attributes
 * history and adding spacing to established candidates (i.e. attributes) or
 * accumulation spacing in case of candidate absence.
 */
public class RtfSpaceManager {
    /** Stack for saving rtf block-level attributes. */
    private LinkedList blockAttributes = new LinkedList();

    /** Stack for saving rtf inline-level attributes. */
    private LinkedList inlineAttributes = new LinkedList();

    /**
     * Keeps value of accumulated space in twips. For example if block has
     * nonzero space-before or space-after properties and has no plain text
     * inside, then the next block should has increased value of space-before
     * property.
     */
    private int accumulatedSpace;

    /**
     * Construct a newly allocated <code>RtfSpaceManager</code> object.
     */
    public RtfSpaceManager() {
    }

    /**
     * Iterates block-level stack (i.e. all open blocks) and stops updating
     * candidate for adding space-before/space-after attribute in case of
     * candidate presence.
     */
    public void stopUpdatingSpaceBefore() {
        for (Object blockAttribute : blockAttributes) {
            RtfSpaceSplitter splitter = (RtfSpaceSplitter) blockAttribute;
            if (splitter.isBeforeCadidateSet()) {
                splitter.stopUpdatingSpaceBefore();
            }
        }
    }

    /**
     * Set attributes as candidate for space attributes inheritance.
     *
     * @param attrs  attributes to set
     */
    public void setCandidate(RtfAttributes attrs) {
        for (Object blockAttribute : blockAttributes) {
            RtfSpaceSplitter splitter = (RtfSpaceSplitter) blockAttribute;
            splitter.setSpaceBeforeCandidate(attrs);
            splitter.setSpaceAfterCandidate(attrs);
        }
    }

    /**
     * Builds RtfSpaceSplitter on <code>attrs</code> and adds it to the
     * block-level stack.
     *
     * @param attrs  RtfAttribute to add
     * @return instance of RtfSpaceSplitter
     */
    public RtfSpaceSplitter pushRtfSpaceSplitter(RtfAttributes attrs) {
        RtfSpaceSplitter splitter;
        splitter = new RtfSpaceSplitter(attrs, accumulatedSpace);
        // set accumulatedSpace to 0, because now accumulatedSpace used
        // in splitter
        accumulatedSpace = 0;
        blockAttributes.addLast(splitter);
        return splitter;
    }

    /**
     * Removes RtfSpaceSplitter from top of block-level stack.
     */
    public void popRtfSpaceSplitter() {
        if (!blockAttributes.isEmpty()) {
            RtfSpaceSplitter splitter;
            splitter = (RtfSpaceSplitter) blockAttributes.removeLast();
            accumulatedSpace += splitter.flush();
        }
    }

    /**
     * Pushes inline attributes to inline-level stack.
     *
     * @param attrs attributes to add
     */
    public void pushInlineAttributes(RtfAttributes attrs) {
        inlineAttributes.addLast(attrs);
    }

    /**
     * Pops inline attributes from inline-level stack.
     */
    public void popInlineAttributes() {
        if (!inlineAttributes.isEmpty()) {
            inlineAttributes.removeLast();
        }
    }

    /**
     * Peeks at inline-level attribute stack.
     *
     * @return RtfAttributes from top of inline-level stack
     */
    public RtfAttributes getLastInlineAttribute() {
        return (RtfAttributes) inlineAttributes.getLast();
    }
}