How to extend the Eclipse Java Editor to add coloured overlays

Question

I have an idea for an Eclipse plugin which I've been toying with. I need to be able to extend the Eclipse Java Editor component and add coloured overlays to the code based on pluggable external metrics. Unfortunately there doesn't appear to be any kind of syntax highlighting extension point.

Does anyone know how I might be able to extend the exisitng eclipse Java Editor to add custom highlighting rules?

Bear in mind I'm new to Eclipse plugin programming so please give as much detail as possible.

Answer 1

The base class of the Eclipse 3.5 Java editor is org.eclipse.jdt.internal.ui.text.java

Note the "internal" in the class name. That means it's an internal Eclipse class, and not meant to be extended.

There is an Eclipse extension point org.eclipse.ui.editors.markerUpdaters I've not worked with this extension point, but it appears that it might allow you to do what you wish.

Here's the description from Eclipse help:

This extension point is used for registering marker update strategies with marker annotation models. A resource that is opened in a text editor is associated with a marker annotation model. For each marker attached to the resource this model manages a position that is updated with each change applied to the text in the editor. If the resource is saved, the text in the editor and the position managed for a marker are passed over to the registered marker update strategies. These strategies can then update the marker's attributes based on the text and the position. Marker update strategies are requested to implement the interface org.eclipse.ui.texteditor.IMarkerUpdater. The update strategies can be registered either for a particular marker type or all marker types. The latter by omitting any marker type in the extension.

Here's an example from the Eclipse help:

<extension point= "org.eclipse.ui.editors.markerUpdaters"> 
    <updater 
        id="org.eclipse.jdt.ui.markerUpdaters.JavaSearchMarkerUpdater" 
        class="org.eclipse.jdt.internal.ui.search.JavaSearchMarkerUpdater" 
        markerType="org.eclipse.search.searchmarker"> 
    </updater> 
</extension> 

I couldn't find more of an explanation on the Internet.