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Java > Open Source Codes > org > apache > fop > layoutmgr > ListElement


1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one or more
3  * contributor license agreements. See the NOTICE file distributed with
4  * this work for additional information regarding copyright ownership.
5  * The ASF licenses this file to You under the Apache License, Version 2.0
6  * (the "License"); you may not use this file except in compliance with
7  * the License. You may obtain a copy of the License at
8  *
9  * http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  */
17
18 /* $Id: ListElement.java 426576 2006-07-28 15:44:37Z jeremias $ */
19
20 package org.apache.fop.layoutmgr;
21
22 /**
23  * This class is the base class for all kinds of elements that are added to element lists. There
24  * are basically two kinds of list elements: Knuth elements and unresolved elements like spaces,
25  * border and padding elements which are converted to Knuth elements prior to the breaking
26  * process.
27  */
28 public abstract class ListElement {
29
30     private Position position;
31     
32     /**
33      * Main constructor
34      * @param position the Position instance needed by the addAreas stage of the LMs.
35      */
36     public ListElement(Position position) {
37         this.position = position;
38     }
39     
40     /**
41      * @return the Position instance for this element.
42      */
43     public Position getPosition() {
44         return this.position;
45     }
46     
47     /**
48      * Change the Position stored in this element.
49      * @param position the Position instance
50      */
51     public void setPosition(Position position) {
52         this.position = position;
53     }
54
55     /**
56      * @return the LayoutManager responsible for this element.
57      */
58     public LayoutManager getLayoutManager() {
59         if (position != null) {
60             return position.getLM();
61         } else {
62             return null;
63         }
64     }
65
66     /** @return true if this element is a KnuthBox. */
67     public boolean isBox() {
68         return false;
69     }
70
71     /** @return true if this element is a KnuthGlue. */
72     public boolean isGlue() {
73         return false;
74     }
75
76     /** @return true if this element is a KnuthPenalty. */
77     public boolean isPenalty() {
78         return false;
79     }
80
81     /** @return true if the element is a penalty and represents a forced break. */
82     public boolean isForcedBreak() {
83         return false;
84     }
85
86     /** @return true if the element is an unresolved element such as a space or a border. */
87     public boolean isUnresolvedElement() {
88         return true;
89     }
90     
91 }
92
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