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Abstract

compass After providing the basic example of how the Eclipse Common Navigator Framework (CNF) can be used to display custom content, this article focuses on the main feature of the CNF – the contribution of content to the same navigator by several independent plug-ins. First of all, I will explain some minor changes introduced to the CNF in the Gallileo Edition, then I will focus on the content itself and finally provide an overview of how the action contributions can be provided. In the end of the post, some ideas on control of dynamic content are explained.

Gallileo Changes

There are two noticeable changes in the CNF that have been added with Eclipse Galileo. The return type of the method continue reading…

As announced in a previous post the Eclipse Demo Camp Hamburg – Galileo Edition took place in the East Hotel in Hamburg. Organized by Peter and Martin, the event was again an interesting meeting with Eclipse-interested people in a wonderful location. Five presenters introduced Eclipse and OSGi-related topics. Moritz Eysholdt reported about the (Meta)Model Evolutions, he was focusing on during his masters thesis. The interesting part of his solution are two Xtext DSLs for description of the Metamodel changes (EPatch) and model migration algorithms (MetaPatch). Heiko Behrens gave a funny and really good introduction of Xtext and DSLs for not Xtext developers. I really like his examples: these are simple and understanding for everyone. Great job! Marco Mosconi showed some ObjectTeams (black) magic. A very intersting technology using aspect-oriented programming for type-safe framework modifications. Seem to be pretty advanced technology with interesting tooling. Markus Alexander Kuppe had a talk on ECF and RFC 119 and gave some sneak preview of the upcomming features. Finally, I had a short talk on Common Navigator Framework, basically explaining the article posted here and something I documented for Galileo. Here are some visual impressions: my FlickR set and  Peter’s.

compas

Abstract

This article describes some efforts to use the Common Navigator Framework (CNF). In doing so it incorporates the information already covered in different articles, but also focuses on the specific use case of providing a view of something completely unrelated to the platform resources. So the aim is not to add some content to the “Project Explorer” which is an example of resource-oriented CNF usage, but to provide a view on a completely own data model.

Introduction

Project Explorer
A very common UI element to represent data is a tree view. In SWT this UI element is implemented using the Tree widget. Following the MVC design pattern in the TreeViewer, JFace simplifies the usage of the Tree widget by delegating the task of content adoption to the ContentProvider and the label production to the LabelProvider (and using Sorters and Filters for sorting and filtering). Still for a single representation one has to construct a viewer and configure it with a corresponding Label- and ContentProvider. Further code reduction can be achieved by the use of WorkbenchContentProvider and WorkbenchLabelProvider if the elements can be made adaptable (implement IAdaptable interface and making them first-class workbench citizens). This approach is helpful, if the elements has to be displayed in several different viewers (e.G. Table). Finally, the Common Navigator Framework (CNF) is a facility provided by the Eclipse Platform which allows the usage of multiple Label- and ContentProvider on the same view. The providers are activated and used dynamically and can be configured declarative or programmatically. The advantage of CNF approach is the ability to combine elements in one view which have different origins(e.G. contributed by different plugins). CNF is used in Eclipse IDE: e.G. “ProjectExplorer” and “CVS Synchrnoize” are both instances of the CNF.

The usage of the CNF in your own application for purposes of representation of resource-based (and usually file-based) content is discussed in articles of Micael Elder in detail. The main idea is to instantiate the view, declare the default content and UI interface and make some additions where needed. This post has a different aim: we start from scratch and represent completely resource unrelated content. Before diving in the implementation details, some overview is provided.

UI Overview

Project Explorer with default options There are many things which can be configured by the usage of CNF and it is beyond the scope of this post to cover all of them. Still there are several things to understand before the actual code can be written. The user interacts with a View which shows the data elements. Which elements are shown is configured using the navigation content extensions. Shown elements can be filtered with Filters and sorted using Sorters on behalf of the user. There are some predefined actions and their positions in the UI and corresponding extension points to contribute to. Project Explorer Pop-up. The actions for Working sets, Customize View, Link with editor belong to this category. The user can also right-click on particular element in the tree and sees a popup-menu. This menu is configured based on the content element and can be (is) contributed by several plugins. The action contribution is also covered in the article series from Michael Elder.

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