plugin-implement-quicknotepad.html

/www/tags/NOV_07_2009/htdocs/42docs/users-guide/plugin-implement-quicknotepad.html

#
HTML | 157 lines | 136 code | 21 blank | 0 comment | 0 complexity | 3c6d1a5d1c0fc58e957141b160d45974 MD5 | raw file
Possible License(s): BSD-3-Clause, AGPL-1.0, Apache-2.0, LGPL-2.0, LGPL-3.0, GPL-2.0, CC-BY-SA-3.0, LGPL-2.1, GPL-3.0, MPL-2.0-no-copyleft-exception, IPL-1.0

<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>The QuickNotepad Class</title><meta name="generator" content="DocBook XSL Stylesheets V1.65.1"><link rel="home" href="index.html" title="jEdit 4.2 User's Guide"><link rel="up" href="plugin-implement.html" title="Chapter 18. Implementing a Simple Plugin"><link rel="previous" href="plugin-implement-dockables.html" title="The Dockable Window Catalog"><link rel="next" href="plugin-implement-quicknotepadtoolbar.html" title="The QuickNotepadToolBar Class"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">The QuickNotepad Class</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="plugin-implement-dockables.html">Prev</a> </td><th width="60%" align="center">Chapter 18. Implementing a Simple Plugin</th><td width="20%" align="right"> <a accesskey="n" href="plugin-implement-quicknotepadtoolbar.html">Next</a></td></tr></table><hr></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="plugin-implement-quicknotepad"></a>The QuickNotepad Class</h2></div></div><div></div></div><p>
  Here is where most of the features of the plugin will be implemented.
  To work with the dockable window API, the top level window will be a
  <tt class="classname">JPanel</tt>.  The visible components reflect a
  simple layout. Inside the top-level panel we will place a scroll pane with
  a text area. Above the scroll pane we will place a panel containing a small
  tool bar and a label displaying the path of the current notepad file.
</p><p>
  We have identified three user actions that need
  implementation here: <tt class="function">chooseFile()</tt>,
  <tt class="function">saveFile()</tt>, and
  <tt class="function">copyToBuffer()</tt>. As noted earlier, we also want the
  text area to change its appearance in immediate response to a change in
  user options settings. In order to do that, the window class must
  respond to a <tt class="classname">PropertiesChanged</tt> message from
  the EditBus.
</p><p>
  Unlike the <tt class="classname">EBPlugin</tt> class, the
  <tt class="classname">EBComponent</tt> interface does not deal with the
  component's actual subscribing and unsubscribing to the EditBus.  To
  accomplish this, we use a pair of methods inherited from the
  Java platform's <tt class="classname">JComponent</tt> class
  that are called when the window is made visible, and when it is hidden.
  These two methods,
  <tt class="function">addNotify()</tt> and
  <tt class="function">removeNotify()</tt>, are overridden to add and remove
  the visible window from the list of EditBus subscribers.
</p><p>
  We will provide for two minor features when the notepad is
  displayed in the floating window.  First, when a floating plugin window
  is created, we will give the notepad text area input focus.  Second,
  when the notepad if floating and has input focus, we will have the
  <tt class="keycap">Escape</tt> key dismiss the notepad window.  An
  <tt class="classname">AncestorListener</tt> and a
  <tt class="classname">KeyListener</tt> will implement these details.
</p><p>
  Here is the listing for the data members, the constructor, and the
  implementation of the <tt class="classname">EBComponent</tt> interface:
</p><div class="informalexample"><table border="0" bgcolor="#E0E0E0"><tr><td><pre class="programlisting">public class QuickNotepad extends JPanel
    implements EBComponent
{
    private String filename;
    private String defaultFilename;
    private View view;
    private boolean floating;

    private QuickNotepadTextArea textArea;
    private QuickNotepadToolPanel toolPanel;

    //
    // Constructor
    //

    public QuickNotepad(View view, String position)
    {
        super(new BorderLayout());

        this.view = view;
        this.floating = position.equals(
            DockableWindowManager.FLOATING);

        this.filename = jEdit.getProperty(
            QuickNotepadPlugin.OPTION_PREFIX
            + "filepath");
        if(this.filename == null || this.filename.length() == 0)
        {
            this.filename = new String(jEdit.getSettingsDirectory()
                + File.separator + "qn.txt");
            jEdit.setProperty(QuickNotepadPlugin.OPTION_PREFIX
                + "filepath",this.filename);
        }
        this.defaultFilename = new String(this.filename);

        this.toolPanel = new QuickNotepadToolPanel(this);
        add(BorderLayout.NORTH, this.toolPanel);

        if(floating)
            this.setPreferredSize(new Dimension(500, 250));

        textArea = new QuickNotepadTextArea();
        textArea.setFont(QuickNotepadOptionPane.makeFont());
        textArea.addKeyListener(new KeyHandler());
        textArea.addAncestorListener(new AncestorHandler());
        JScrollPane pane = new JScrollPane(textArea);
        add(BorderLayout.CENTER, pane);

        readFile();
    }

    //
    // Attribute methods
    //

    // for toolBar display
    public String getFilename()
    {
        return filename;
    }

    //
    // EBComponent implementation
    //

    public void handleMessage(EBMessage message)
    {
        if (message instanceof PropertiesChanged)
        {
            propertiesChanged();
        }
    }


    private void propertiesChanged()
    {
        String propertyFilename = jEdit.getProperty(
            QuickNotepadPlugin.OPTION_PREFIX + "filepath");
        if(!defaultFilename.equals(propertyFilename))
        {
            saveFile();
            toolPanel.propertiesChanged();
            defaultFilename = propertyFilename.clone();
            filename = defaultFilename.clone();
            readFile();
        }
        Font newFont = QuickNotepadOptionPane.makeFont();
        if(!newFont.equals(textArea.getFont()))
        {
            textArea.setFont(newFont);
            textArea.invalidate();
        }
    }

    // These JComponent methods provide the appropriate points
    // to subscribe and unsubscribe this object to the EditBus

    public void addNotify()
    {
        super.addNotify();
        EditBus.addToBus(this);
    }


    public void removeNotify()
    {
        saveFile();
        super.removeNotify();
        EditBus.removeFromBus(this);
    }

    ...

}</pre></td></tr></table></div><p>
  This listing refers to a <tt class="classname">QuickNotebookTextArea</tt>
  object. It is currently implemented as a <tt class="classname">JTextArea</tt> with
  word wrap and tab sizes hard-coded.  Placing the object in a separate
  class will simply future modifications.
</p></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="plugin-implement-dockables.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="plugin-implement.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="plugin-implement-quicknotepadtoolbar.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">The Dockable Window Catalog </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> The QuickNotepadToolBar Class</td></tr></table></div></body></html>