The QuickNotepad Class

The QuickNotepad Class
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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 JPanel. 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.

We have identified three user actions that need implementation here: chooseFile(), saveFile(), and copyToBuffer(). 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 PropertiesChanged message from the EditBus.

Unlike the EBPlugin class, the EBComponent 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 JComponent class that are called when the window is made visible, and when it is hidden. These two methods, addNotify() and removeNotify(), are overridden to add and remove the visible window from the list of EditBus subscribers.

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 Escape key dismiss the notepad window. An AncestorListener and a KeyListener will implement these details.

Here is the listing for the data members, the constructor, and the implementation of the EBComponent interface:

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);
    }

    ...

}

This listing refers to a QuickNotebookTextArea object. It is currently implemented as a JTextArea with word wrap and tab sizes hard-coded. Placing the object in a separate class will simply future modifications.

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The services.xml file	Home	The QuickNotepadToolBar Class