Dynamic Menu Item to select Theme in Eclipse IDE

In Bug 514458, I added the “Theme” dynamic menu to the Eclipse IDE. This post explains how I did this.

Menu Eclipse 3.x style

First edit the plugin.xml, and add a menu contribution. With the locationURI menu:org.eclipse.ui.appearance?after=org.eclipse.ui.window.appearance.separator1, you’ll contribute a submenu to the Window > Appearance menu, just after the separator.

Add a Theme menu under the menuContribution, and then add a child dynamic element.

<menuContribution
      locationURI="menu:org.eclipse.ui.appearance?after=org.eclipse.ui.window.appearance.separator1">
   <menu
         id="org.eclipse.ui.appearance.theme"
         label="Theme">
      <dynamic
            class="org.eclipse.ui.internal.actions.ThemeDynamicMenu"
            id="org.eclipse.ui.ide.dynamic1">
      </dynamic>
   </menu>
</menuContribution>

Next, create the java class implementing the dynamic menu, and add mock code to verify the menu works.

public class ThemeDynamicMenu extends ContributionItem {

	@Override
	public void fill(Menu menu, int index) {
		MenuItem menuItem = new MenuItem(menu, SWT.CHECK, index);
		menuItem.setText("Theme 1"); //$NON-NLS-1$
		menuItem.addSelectionListener(new SelectionAdapter() {
			@Override
			public void widgetSelected(SelectionEvent e) {
				// executed on menu select
				System.out.println("Selected"); //$NON-NLS-1$
			}
		});
	}

}

Verify the menu is displayed where you expect, and the submenu dynamic entries are working.

Now remove the line which adds the “Theme 1” item, and rewrite the body of the widgetSelected.

The menu should have one menu item for each available theme, and each widgetSelected(){…} should activate the corresponding theme.

The theme selection code is inspired tothe ViewsPreferencePage one.

/**
 * Implements the Dynamic Menu to choose the Theme.
 */
public class ThemeDynamicMenu extends ContributionItem {

	private static String THEME_ID = "THEME_ID"; //$NON-NLS-1$

	private IThemeEngine engine;
	private boolean highContrastMode;

	public ThemeDynamicMenu() {
		IWorkbench workbench = PlatformUI.getWorkbench();
		MApplication application = workbench.getService(MApplication.class);
		IEclipseContext context = application.getContext();
		engine = context.get(IThemeEngine.class);
		highContrastMode = workbench.getDisplay().getHighContrast();
	}

	@Override
	public void fill(Menu menu, int index) {
		for (ITheme theme : engine.getThemes()) {
			if (!highContrastMode && !Util.isGtk() && theme.getId().equals(E4Application.HIGH_CONTRAST_THEME_ID)) {
				continue;
			}
			MenuItem menuItem = new MenuItem(menu, SWT.CHECK, index);
			menuItem.setText(theme.getLabel());
			menuItem.setData(THEME_ID, theme.getId());
			menuItem.addSelectionListener(new SelectionAdapter() {
				@Override
				public void widgetSelected(SelectionEvent e) {
					engine.setTheme(theme, !highContrastMode);
				}
			});
		}

		menu.addMenuListener(new MenuAdapter() {
			@Override
			public void menuShown(MenuEvent e) {
				for (MenuItem item : menu.getItems()) {
					boolean isActive = item.getData(THEME_ID).equals(engine.getActiveTheme().getId());
					item.setEnabled(!isActive);
					item.setSelection(isActive);
				}
			}
		});

	}

}

Finally, launch the Eclipse IDE to check the menu works as expected.