Description

Description#

The main GUI (= weka.gui.Main) contains a plugin mechanism to add functionality to the main menu without having to modify the code of that class (the GUIChooser in the developer version as well). Thanks to the automatic class discovery, Weka will display all components that are found in packages listed in the GenericPropertiesCreator.props file.

Version#

3.5.5

Requirements#

The are only two requirements for components to be listed in the main menu (under the Extensions menu):

they have to implement the weka.gui.MainMenuExtension interface
the packages they reside in must be listed in the GenericPropertiesCreator.props under the weka.gui.MainMenuExtension entry

Examples#

In the following, I'll present two really simple examples of how to add stuff to the main menu. An item that gets added to the main menu either handles everything itself, i.e., creating frame and displaying it, or it needs a frame to place its GUI components in. In the first case, one only needs to let the getActionListener(JFrame) method return an ActionListener and implement the fillFrame(Component) method with an empty body. In the other case, one lets the getActionListener(JFrame) method return null and uses the fillFrame(Component) method to fill the frame with life.

Launching a browser#

Launching a browser with the Weka homepage is a really example, since one only needs to use the weka.gui.BrowserHelper class to launch a browser with a specific URL. Since we don't need a frame for this, we don't add any functionality to the fillFrame(Component), but only let the getActionListener(JFrame) method return an ActionListener that launches the browser with the Weka homepage. The StartBrowser.java extension will be listed in the sub-menu Internet as Start browser.

  public String getSubmenuTitle() {
    return "Internet";
  }

  public String getMenuTitle() {
    return "Start browser";
  }

  public ActionListener getActionListener(JFrame owner) {
    final JFrame finalOwner = owner;

    ActionListener result = new ActionListener() {
      public void actionPerformed(ActionEvent evt) {
    BrowserHelper.openURL(finalOwner, "http://www.cs.waikato.ac.nz/~ml/weka/");
      }
    };

    return result;
  }

  public void fillFrame(Component frame) {
  }

Since the class is part of the weka.gui.extensions package, we must add this package to the weka.gui.MainMenuExtension entry of the GenericPropertiesCreator.props file, e.g.:

 weka.gui.MainMenuExtension=\
  weka.gui.extensions

SQL Worksheet#

The SqlWorksheet.java mode, one needs to take care of to check for JFrame and JInternalFrame as ancestor of the frame that is being passed through. The method only instantiates an SqlViewer panel, places it in the center of the frame, resizes the frame to 800x600 and moves it into the center of the screen.

  public String getSubmenuTitle() {
    return null;
  }

  public String getMenuTitle() {
    return "SQL Worksheet";
  }

  public ActionListener getActionListener(JFrame owner) {
    return null;
  }

  public void fillFrame(Component frame) {
    SqlViewer sql = new SqlViewer(null);

    * add sql viewer component
    if (frame instanceof JFrame) {
      JFrame f = (JFrame) frame;
      f.setLayout(new BorderLayout());
      f.add(sql, BorderLayout.CENTER);
      f.pack();
    }
    else if (frame instanceof JInternalFrame) {
      JInternalFrame f = (JInternalFrame) frame;
      f.setLayout(new BorderLayout());
      f.add(sql, BorderLayout.CENTER);
      f.pack();
    }

    * size + location (= centered)
    frame.setSize(800, 600);
    frame.validate();
    int screenHeight = frame.getGraphicsConfiguration().getBounds().height;
    int screenWidth  = frame.getGraphicsConfiguration().getBounds().width;
    frame.setLocation(
      (screenWidth - frame.getBounds().width) / 2,
      (screenHeight - frame.getBounds().height) / 2);
  }

This class is part of the weka.gui.extensions package and we therefore must add this package to the weka.gui.MainMenuExtension entry of the GenericPropertiesCreator.props file:

 weka.gui.MainMenuExtension=\
  weka.gui.extensions