e4-preferences

This project contains a plug-in with an OSGi declarative service that can be used to contribute preference pages to a JFace PreferenceDialog via OSGi services.

This plug-in can be used for migrating an Eclipse 3.x based application to using the Eclipse 4.x platform. It is intended to remove the extension point org.eclipse.ui.preferencePages and dependencies to org.eclipse.ui, which is necessary to get rid of the compatibility layer.

To consume the service via target platform, the following update sites are available:

• 0.2.0 (works with Java 7 and Eclipse Luna)
  https://github.com/fipro78/e4-preferences/raw/master/releases/0.2.0
• 0.3.0 (works with Java 8 and Eclipse 2019-06 because of OSGi R7 Logging)
  https://github.com/fipro78/e4-preferences/raw/master/releases/0.3.0
• 0.4.0 (works with Java 17 and Eclipse 2024-03 because of jakarta.inject annotations)
  https://github.com/fipro78/e4-preferences/raw/master/releases/0.4.0
• 0.5.0 (works with Java 17 and Eclipse 2024-03 because of jakarta.inject annotations)
  https://github.com/fipro78/e4-preferences/raw/master/releases/0.5.0
  Uses a IContextFunction instead of an ExtendedObjectSupplier which avoids the usage of the @PrefMgr annotation.

To use the service, existing preference pages need to be modified:

1. Remove the class hierarchy (implements IWorkbenchPreferencePage)

2. Remove init()

3. Implement a constructor to set the title and the description if necessary

4. Remove the extension point org.eclipse.ui.preferencePages

To contribute the preference page to this service, the following steps need to be performed:

5. Add org.fipro.e4.service.preferences to the Dependencies section of the MANIFEST.MF file of the plug-in that contributes the preference page
6. Enable DS Annotations support via Window - Preferences - Plug-in Development - DS Annotations
7. Create a PreferenceNodeContribution for the PreferencePage (e.g. MyPreferencePage)

@Component(service=PreferenceNodeContribution.class)
public class MyPreferenceContribution extends PreferenceNodeContribution {

    public MyPreferenceContribution() {
        super("myId", "myLabel", null, 
            MyPreferencePage.class, null, null);
    }
}

To open a JFace PreferenceDialog that looks similar to the known Eclipse workbench preference dialog, you need to create a handler that looks similar to the following snippet:

public class PreferencesHandler {
	
    @Execute
    public void execute(Shell shell, PreferenceManager manager) {
        PreferenceDialog dialog = new PreferenceDialog(shell, manager) {
        
        @Override
        protected TreeViewer createTreeViewer(Composite parent) {
            TreeViewer viewer = super.createTreeViewer(parent);
				
            viewer.setComparator(new ViewerComparator() {
					
                @Override
                public int category(Object element) {
                    // this ensures that the General preferences page is always on top
                    // while the other pages are ordered alphabetical
                    if (element instanceof ContributedPreferenceNode
                            && ("general".equals(((ContributedPreferenceNode) element).getId()))) {
                        return -1;
                    }
                    return 0;
                }
            });
				
            return viewer;
			}
        };
		
        dialog.open();
    }
}