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 * 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.
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/* $Id: KnuthGlue.java 985537 2010-08-14 17:17:00Z jeremias $ */

package org.apache.fop.layoutmgr;

import org.apache.fop.traits.MinOptMax;

An instance of this class represents a piece of content with adjustable
width: for example a space between words of justified text.
A KnuthGlue is a feasible breaking point only if it immediately follows
a KnuthBox.
The represented piece of content is suppressed if either the KnuthGlue
is a chosen breaking point or there isn't any KnuthBox between the
previous breaking point and the KnuthGlue itself.
So, an unsuppressible piece of content with adjustable width, for example
a leader or a word with adjustable letter space, cannot be represented
by a single KnuthGlue; it can be represented using the sequence:
  KnuthBox(width = 0)
  KnuthPenalty(width = 0, penalty = infinity)
  KnuthGlue(...)
  KnuthBox(width = 0)
where the infinity penalty avoids choosing the KnuthGlue as a breaking point
and the 0-width KnuthBoxes prevent suppression.
Besides the inherited methods and attributes, this class has two attributes
used to store the stretchability (difference between max and opt width) and
the shrinkability (difference between opt and min width), and the methods
to get these values.
/**
 * An instance of this class represents a piece of content with adjustable
 * width: for example a space between words of justified text.
 *
 * A KnuthGlue is a feasible breaking point only if it immediately follows
 * a KnuthBox.
 *
 * The represented piece of content is suppressed if either the KnuthGlue
 * is a chosen breaking point or there isn't any KnuthBox between the
 * previous breaking point and the KnuthGlue itself.
 *
 * So, an unsuppressible piece of content with adjustable width, for example
 * a leader or a word with adjustable letter space, cannot be represented
 * by a single KnuthGlue; it can be represented using the sequence:
 *   KnuthBox(width = 0)
 *   KnuthPenalty(width = 0, penalty = infinity)
 *   KnuthGlue(...)
 *   KnuthBox(width = 0)
 * where the infinity penalty avoids choosing the KnuthGlue as a breaking point
 * and the 0-width KnuthBoxes prevent suppression.
 *
 * Besides the inherited methods and attributes, this class has two attributes
 * used to store the stretchability (difference between max and opt width) and
 * the shrinkability (difference between opt and min width), and the methods
 * to get these values.
 */
public class KnuthGlue extends KnuthElement {

    private final int stretch;
    private final int shrink;
    private final Adjustment adjustmentClass;

    
Creates a new KnuthGlue.
Params:
minOptMax – a MinOptMax where the opt-value is mapped to the width, the 
                 stretchability is mapped to the stretchability and the the shrinkability is mapped to the shrinkability
pos –       the Position stored in this glue
auxiliary – is this glue auxiliary?/**
     * Creates a new <code>KnuthGlue</code>.
     *
     * @param minOptMax a <code>MinOptMax</code> where the {@link MinOptMax#getOpt() opt-value} is
     *                  mapped to the width, the {@link MinOptMax#getStretch()
     *                  stretchability} is mapped to the stretchability and the the {@link
     *                  MinOptMax#getShrink() shrinkability} is mapped to the shrinkability
     * @param pos       the Position stored in this glue
     * @param auxiliary is this glue auxiliary?
     */
    public KnuthGlue(MinOptMax minOptMax, Position pos, boolean auxiliary) {
        super(minOptMax.getOpt(), pos, auxiliary);
        this.stretch = minOptMax.getStretch();
        this.shrink = minOptMax.getShrink();
        this.adjustmentClass = Adjustment.NO_ADJUSTMENT;
    }

    
Creates a new KnuthGlue.
Params:
width –     the width of this glue
stretch –   the stretchability of this glue
shrink –    the shrinkability of this glue
pos –       the Position stored in this glue
auxiliary – is this glue auxiliary?/**
     * Creates a new <code>KnuthGlue</code>.
     *
     * @param width     the width of this glue
     * @param stretch   the stretchability of this glue
     * @param shrink    the shrinkability of this glue
     * @param pos       the Position stored in this glue
     * @param auxiliary is this glue auxiliary?
     */
    public KnuthGlue(int width, int stretch, int shrink, Position pos,
                     boolean auxiliary) {
        super(width, pos, auxiliary);
        this.stretch = stretch;
        this.shrink = shrink;
        this.adjustmentClass = Adjustment.NO_ADJUSTMENT;
    }

    
Creates a new KnuthGlue.
Params:
width –     the width of this glue
stretch –   the stretchability of this glue
shrink –    the shrinkability of this glue
adjustmentClass – the adjsutment class
pos –       the Position stored in this glue
auxiliary – is this glue auxiliary?/**
     * Creates a new <code>KnuthGlue</code>.
     *
     * @param width     the width of this glue
     * @param stretch   the stretchability of this glue
     * @param shrink    the shrinkability of this glue
     * @param adjustmentClass the adjsutment class
     * @param pos       the Position stored in this glue
     * @param auxiliary is this glue auxiliary?
     */
    public KnuthGlue(int width, int stretch, int shrink, Adjustment adjustmentClass,
                     Position pos, boolean auxiliary) {
        super(width, pos, auxiliary);
        this.stretch = stretch;
        this.shrink = shrink;
        this.adjustmentClass = adjustmentClass;
    }

    
{@inheritDoc} /** {@inheritDoc} */
    public boolean isGlue() {
        return true;
    }

    
Returns:
the stretchability of this glue./** @return the stretchability of this glue. */
    public int getStretch() {
        return stretch;
    }

    
Returns:
the shrinkability of this glue./** @return the shrinkability of this glue. */
    public int getShrink() {
        return shrink;
    }

    
Returns:
the adjustment class (or role) of this glue./** @return the adjustment class (or role) of this glue. */
    public Adjustment getAdjustmentClass() {
        return adjustmentClass;
    }

    
{@inheritDoc} /** {@inheritDoc} */
    public String toString() {
        StringBuffer buffer = new StringBuffer(64);
        if (isAuxiliary()) {
            buffer.append("aux. ");
        }
        buffer.append("glue");
        buffer.append(" w=").append(getWidth());
        buffer.append(" stretch=").append(getStretch());
        buffer.append(" shrink=").append(getShrink());
        if (!getAdjustmentClass().equals(Adjustment.NO_ADJUSTMENT)) {
            buffer.append(" adj-class=").append(getAdjustmentClass());
        }
        return buffer.toString();
    }

}