Developing an Eclipse Plug-in David Gallardo

Platform Runtime Workspace Help Team Workbench JFace SWT Eclipse Project Java Development Tools (JDT) Their Tool Your Tool Another Tool Eclipse Overview Plug-in Development Environment (PDE) Eclipse Platform Debug

The Eclipse JDT and PDE Java VM Standard Java2 Virtual Machine Platform Eclipse Platform Java development tools JDTPDE Plug-in development environment

Eclipse Plug-in Architecture Plug-in - smallest unit of Eclipse function –Big example: HTML editor –Small example: Action to create zip files Extension point - named entity for collecting “contributions” –Example: extension point for workbench preference UI Extension - a contribution –Example: specific HTML editor preferences

Eclipse Plug-in Architecture Each plug-in –Contributes to 1 or more extension points –Optionally declares new extension points –Depends on a set of other plug-ins –Contains Java code libraries and other files –May export Java-based APIs for downstream plug-ins –Lives in its own plug-in subdirectory Details spelled out in the plug-in manifest –Manifest declares contributions –Code implements contributions and provides API –plugin.xml file in root of plug-in subdirectory

Plug-in Manifest <plugin = “Example Plug-in Tool" class = "com.example.tool.ToolPlugin"> id = “com.example.tool" name <page id = "com.example.tool.preferences" icon = "icons/knob.gif" title = “Tool Knobs" class = "com.example.tool.ToolPreferenceWizard“/> Declare contribution this plug-in makes Declare new extension point open to contributions from other plug-ins Location of plug-in’s code Other plug-ins needed Plug-in identification plugin.xml

Eclipse Plug-in Architecture Plug-in A –Declares extension point P –Declares interface I to go with P Plug-in B –Implements interface I with its own class C –Contributes class C to extension point P Plug-in A instantiates C and calls its I methods plug-in Aplug-in B class C interface I extension point P extension Typical arrangement: contributes creates, calls implements

Eclipse Platform Architecture Eclipse Platform Runtime is micro-kernel –All functionality supplied by plug-ins Eclipse Platform Runtime handles start up –Discovers plug-ins installed on disk –Matches up extensions with extension points –Builds global plug-in registry –Caches registry on disk for next time

Using the Eclipse PDE Self-hosted development environment New PDE project wizard creates directory structure and populates Templates for specific types of plug-ins Manifest editor for plugin.xml configuration file –Identify dependencies –Add extension points Run and debug in a separate Eclipse window

Example: A log4j configuration file editor Should look and work like other editors in Eclipse: –Distinguish and allow editing different types of text—comments and values –Provide syntax coloring –Provide code assistance (triggered by Ctrl- Space and context-sensitive

Creating the plug-in project and extension point Create new project Create the “main” text editor class Define the extension point in the manifest file and associate it with the editor class Add icon Run to see default editor behavior

A sample log4j.properties file # Logger log4j.rootLogger=DEBUG, ConApp # Appender log4j.appender.ConApp=org.apache.log4j.ConsoleAppender # PatternLayout log4j.appender.ConApp.layout=org.apache.log4j.PatternLayout log4j.appender.ConApp.layout.ConversionPattern=%d [%t] %-5p %c - %m%n

Working with text Differentiate between sections of text by providing a rule-base partition scanner: –Comments –Values –Everything else Eclipse provides base classes for rule-based scanning, which we’ll extend to support log4j syntax

Working with tokens For each partition type, you need to provide a token scanner: –CommentScanner –ValueScanner –DefaultScanner You also need to provide a token manager to track tokens and their colors –Support user-preferences –Track colors—In SWT, you need to dispose of resources you create

Add content assist Provide a content assist processor for each partition that require content assist (also known as code completion) Return list of possible completions Define character that trigger content assist automatically

Connect to the backing file Eclipse provides an interface— IDocument—that represents the document Assigns a partition scanner to the document And, conversely, assigns the document to the partition scanner JFace class FileDocumentProvider does most of the work

Bringing it all back home The SourceViewerConfiguration class ties everything together: –Determines partition types, default partition –Set up the partitions –Provide damagers and repairers for each partion –Turn on content assist

Finishing touches: The editor class Now we can finish the editor class we started with: –Plug in the source configuration –Plug in document provider –Attach to Eclipse preference store –Handle calls to redraw text when necessary –Handle calls to update preferences –Plug in content assist as a retargetable action

Demo Import example source Walk through source code demonstrating the components previously described Run and demonstrate: –New Eclipse Menu item –Default editor for log4j.properties –Syntax coloring –Content assist