Themes for NetBeans Platform Applications

Today I found out, from David Strupl on the NetBeans Platform mailing list, that NetBeans Platform applications can have themes/skins defined, via XML files. That means that I hadn't read the Main class of the NetBeans Platform before, where I would have found the following method:

 public static void initUICustomizations() {
  if (!CLIOptions.isGui ()) {
      return;
  }

  URL themeURL = null;
  boolean wantTheme = Boolean.getBoolean ("netbeans.useTheme") ||
      CLIOptions.uiClass != null && CLIOptions.uiClass.getName().indexOf("MetalLookAndFeel") >= 0;

  try {
      if (wantTheme) {
          //Put a couple things into UIDefaults for the plaf library to process if it wants
           FileObject fo = FileUtil.getConfigFile("themes.xml"); //NOI18N
           if (fo == null) {            
                // File on SFS failed --> try to load from a jar from path
                // /org/netbeans/core/startup/resources/themes.xml
                try {
                    themeURL = new URL("nbresloc:/org/netbeans/core/startup/resources/themes.xml"); //NOI18N
                    // check whether the file is there:
                    themeURL.openStream().close();
                } catch (IOException ex) {
                    themeURL = null;
                }
           } else {
                try {
                    themeURL = fo.getURL();
                } catch (FileStateInvalidException fsie) {
                    //do nothing
                }
           }
      }
  } finally {
      CoreBridge.getDefault ().initializePlaf(CLIOptions.uiClass, CLIOptions.getFontSize(), themeURL);
  }
  if (CLIOptions.getFontSize() > 0 && "GTK".equals(UIManager.getLookAndFeel().getID())) { //NOI18N
      Util.err.warning(NbBundle.getMessage(Main.class,
      "GTK_FONTSIZE_UNSUPPORTED")); //NOI18N
  }
  StartLog.logProgress("Fonts updated"); // NOI18N
}

So, you can define a "themes.xml" file, in certain places, which the NetBeans Platform will then pick up and apply to the application. If you're not using Metal, then you need to provide a special setting to enable themes support.

Here's where I define my "themes.xml" file:

And all the definitions of the content of the file can be found here: http://ui.netbeans.org/docs/ui/themes/themes.html

Some sample themes are included, though they're not necessarily aesthetically pleasing, you can definitely see that something different happened to the application:

Where might themes be useful? Well, here's a themes file that could be pretty handy...

<themeset active="tableRows">

    <theme name="tableRows">
        <color key="Table.background1" r="170" g="144" b="119"/>
        <color key="Table.selectionBackground1" r="190" g="170" b="140"/>
        <color key="Table.background2" r="250" g="240" b="210"/>
        <color key="Table.selectionBackground2" r="198" g="183" b="157"/>
    </theme>

</themeset>

...since it results in the table rows below having alternate colors:

However, if you were using Nimbus, you wouldn't need the above theme, since Nimbus shows alternate colors out of the box:

In the case of Nimbus, and all other non-Metal look-and-feels, you need to (as can be read in the code at the top of this article) set "-J-Dnetbeans.useTheme=true" in the "platform.properties" of the application, if you want to use a themes file:

run.args.extra=--laf com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel -J-Dnetbeans.useTheme=true

The above will then enable a Nimbus look-and-feel to have a limited subset of theme definitions being available to it, such as these for enlarging the font:

Pretty cool that themes support is available and that it is fairly easy to apply them in this way.