Element


1   package jimm.datavision;
2   import jimm.util.XMLWriter;
3   import java.util.Observer  ;
4   import java.util.Observable  ;
5   
6   /**
7    * <code>Element</code> is the abstract superclass of <code>Field</code>
8    * and <code>Line</code>. These are the visual elements of a report section.
9    *
10   * @author Jim Menard, <a HREF="mailto:jimm@io.com">jimm@io.com</a>
11   */
12  
13  public abstract class Element
14      extends Observable  
15      implements Writeable, Observer  
16  {
17  
18  protected Report report;
19  protected Section section;
20  protected boolean visible;
21  
22  /**
23   * Constructor. (Though a section knows about it's report, too, often we
24   * create elements with a <code>null</code> section and then add them to
25   * some section later on).
26   *
27   * @param report the report containing this element
28   * @param section the report section containing this element
29   */
30  public Element(Report report, Section section, boolean visible) {
31      this.report = report;
32      this.section = section;
33      this.visible = visible;
34  }
35  
36  public void update(Observable   o, Object   arg) {
37      setChanged();
38      notifyObservers(arg);
39  }
40  
41  /**
42   * Returns the section that containts this field.
43   *
44   * @return the section
45   */
46  public Section getSection() { return section; }
47  
48  /**
49   * Returns the report that containts this field.
50   *
51   * @return the report
52   */
53  public Report getReport() { return report; }
54  
55  /**
56   * Modifies the section to which this field belongs. Only called by
57   * section itself.
58   *
59   * @param s the section
60   */
61  public void setSection(Section s) {
62      if (s != section) {
63      section = s;
64      setChanged();
65      notifyObservers();
66      }
67  }
68  
69  /**
70   * Returns the visible state of this element.
71   *
72   * @return the visible state
73   */
74  public boolean isVisible() { return visible; }
75  
76  /**
77   * Sets the visibility of this element.
78   *
79   * @param newVisible the new visible state
80   */
81  public void setVisible(boolean newVisible) {
82      if (visible != newVisible) {
83      visible = newVisible;
84      setChanged();
85      notifyObservers();
86      }
87  }
88  
89  /**
90   * Writes this element as an XML tag. This abstract method is overridden
91   * by the <code>Field</code> and <code>Line</code> subclasses.
92   *
93   * @param out a writer that knows how to write XML
94   */
95  public abstract void writeXML(XMLWriter out);
96  
97  }
98
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