View source for GEF/Contributor Guide

== Prepare your development environment ==

=== Install Java ===
If you want to develop against GEF, any current Java JDK may be used (the code base is backwards compatible to J2SE-1.4). If you want to develop against GEF4, you will need to have a Java 7 JDK including JavaFX 2.2 (Oracle JVM > 1.7.0_45) and a Java 8 JDK installed.

=== Download and Start IDE ===
To develop against GEF or GEF4 we recommend to download an 'Eclipse IDE for Eclipse Committers' for [https://www.eclipse.org/downloads Luna SR2] or [https://www.eclipse.org/downloads/index-developer-default.php Mars] and to prepare it as outlined in the following sections.

If you want to develop against GEF4, the e(fx)clipse JavaFX-PDE-integration tooling that is needed to resolve JavaFX dependencies (from version 2.0.0 onwards) requires that you start your eclipse IDE with a Java 8 JVM. If Java 8 is not your system default, follow the instructions given in [[Eclipse.ini#Specifying_the_JVM|Specifying the JVM]] to specify that a Java 8 JVM is used for starting your IDE. Please note that the Java JVM that is used for starting the IDE is unrelated to your actual development target, which might still refer to BREE J2SE-1.7 and JavaFX 2.2. It is only needed for the e(fx)clipse JavaFX-PDE-integration tooling to work properly.

=== Specify Execution Environment for J2SE-1.7 (and optionally J2SE-1.8) ===
Several GEF4 bundles rely on JavaFX, which is not visible on the OSGi classpath by default (in case of Java 7 this holds for all classes of JavaFX 2.2, in case of Java 8 this holds for the SWT-integration of JavaFX 8). Within your IDE, the e(fx)clipse JavaFX-PDE integration tooling is needed to extend the bundle classpath accordingly (see [[#Install e(fx)clipse JavaFX-PDE-integration|Install e(fx)clipse JavaFX-PDE-integration]] for details). In order to have the JavaFX dependencies of bundles with BREE J2SE-1.7 (JavaFX 2.2) or J2SE-1.8 (JavaFX 8) resolved properly by the e(fx)clipse JavaFX-PDE-integration, the Java execution environments for J2SE-1.7 and J2SE-1.8 have to be properly resolved against matching Java JVMs. Note that it is required to properly resolve J2SE-1.7 to a matching Java 7 JVM even if you want to use a Java 8 JVM for launching a runtime or for later deployment.

As all GEF4 bundles with JavaFX dependencies are compatible to JavaFX 2.2 (or higher) and thus specify a J2SE-1.7 BREE (bundle required execution environment), you will thus have to ensure that a Java 7 JVM, which provides JavaFX 2.2 (e.g. an Oracle JVM), is used to resolve the J2SE-1.7 execution environment in your IDE. The e(fx)clipse JavaFX-PDE integration will only be able to resolve all JavaFX dependencies (of a bundle with J2SE-1.7 BREE), if the respective <code>jfxrt.jar</code> (which bundles the JavaFX 2.2 classes) can be located in the installation location of the JVM, against which the J2SE-1.7 execution environment is resolved. In order to ensure that this is the case, go to "Windows -> Preferences -> Java -> Installed JREs" and ensure a compatible Java SE 7, which provides JavaFX 2.2, is installed. Eclipse will automatically detect the jar libraries provided by the JVM and add it to the registration. Note that the <code>jfxrt.jar</code> will actually not be added to the JVM definition, and that it does not have to be manually added to it either, because the contained JavaFX classes will be added to the classpath of all bundles with javafx.* package imports (and J2SE-1.7 BREE) by the e(fx)clipse JavaFX-PDE-integration automatically. To ensure that the respective JVM is used to resolve the J2SE-1.7 execution environment, go to "Windows -> Preferences -> Java -> Installed JREs -> Execution Environments" and select it there.

While all GEF4 bundles are compatible with JavaFX 2.2 and Java 7, you may decide to use JavaFX 8.0 and Java 8 in your own bundles. In this case, you will have to ensure that in addition to the Java SE 7 JVM, a compatible Java SE 8 JVM, which bundles JavaFX 8.0, is registered as installed JRE and specified to resolve the J2SE-1.8 execution environment. Note that here, the <code>jfxrt.jar</code> will be automatically added to the JRE definition when registering the Java 8 JVM. However, the <code>jfxswt.jar</code> will not be added (it contains the javax.embed.swt.* classes), and it also does not have to be manually added to the JVM definition as well, as it will be added to the classpath of all bundles that have JavaFX dependencies (and J2SE-1.8 BREE) by the e(fx)clipse JavaFX-PDE-integration.

=== Install e(fx)clipse JavaFX-PDE-integration ===
When developing against those GEF4 components that are dependent on JavaFX, it is required to install the e(fx)clipse JavaFX-PDE-integration (<code>org.eclipse.fx.ide.pde.feature</code>) version 2.0.0 into your Eclipse development environment to properly resolve JavaFX dependencies within your workspace. It is needed because JavaFX is not included on any of the default OSGi classpaths, so JavaFX dependencies of the GEF4 bundles will otherwise not be properly resolved (unless you manually add the respective jars to your classpath, which is not recommended).

You can up to now install the required JavaFX-PDE-integration version 2.0.0 from the [http://download.eclipse.org/efxclipse/updates-released/2.0.0/site e(fx)clipse 2.0.0 release site] or the [http://download.eclipse.org/efxclipse/updates-nightly/site e(fx)clipse IDE nightly update-site], where it is provided as the ''e(fx)clipse - IDE - PDE'' feature (<code>org.eclipse.fx.ide.pde.feature.feature.group</code>). e(fx)clipse JavaFX-PDE-integration integration will work with a Luna as well as a Mars development environment.

Having installed the e(fx)clipse JavaFX-PDE-integration in your development environment, it will automatically add additional classpath entries for those bundles that contain classes with javafx.* imports. However, it requires that a JVM, which provides JavaFX, is registered as an installed JRE and is used to resolve the execution environment matching that of the respective bundle (as outlined above). 

'''Please note that from Mars M7 onwards (or more precisely beginning with gef4-master build #2316, 2015-04-25), GEF4 will require e(fx)clipse 2.0.0 explicitly and will not work with earlier versions of e(fx)clipse. This is because GEF4 bundles no longer specify javafx.* package imports, and JavaFX dependencies will thus not be resolved with earlier e(fx)clipse versions.'''

=== Install API Tools Execution Environment Descriptions ===
All production code GEF and GEF4 bundles (i.e. excluding doc and test bundles) are configured to have API tooling enabled. The API checks, which are configured on a project-specific basis, include checks for references that do not exist in the specified execution environment (as all GEF4 API is still provisional, this is the only aspect it is used for in GEF4). As API tooling requires execution environment descriptions to perform the respective checks, these should be installed (you will see warnings for missing execution environment descriptions otherwise otherwise), as outline under [[Execution_Environments#Installing Execution Environment Descriptions]].

=== Install Xtext ===
Parts of the GEF4 DOT code base ('org.eclipse.gef4.dot', 'org.eclipse.gef4.dot.ui') contain sources that are generated by Xtext. These generated sources are not contained in the Git repository and have to be generated locally within the development workspace, either by manually triggering the Xtext artifact generation (see [[#Generate Xtext Artifacts|Generate Xtext Artifacts]]), which requires installation of Xtext Complete SDK into your IDE, or by executing a local Maven build (see [[#Running a headless build locally|Running a headless build locally]]). 

If you want to develop against GEF4 DOT, it is recommended that you install the 'Xtext Complete SDK' into your IDE. Please make sure that you install it in a version matching the desired development target (see [http://git.eclipse.org/c/gef/org.eclipse.gef4.git/tree/org.eclipse.gef4.target org.eclipse.gef4.target]). That is, for Mars the it should best be installed in version 2.8.3 from [http://download.eclipse.org/releases/mars http://download.eclipse.org/releases/mars].

=== Install Oomph Version Management Tool ===
In addition to the API Tools, for the GEF and GEF4 bundles we make use of the Oomph Version Management tool to ensure service revision increments are performed as needed (the tool will provide indications of which bundle and feature versions to update when performing changes on the service level). Please install it from the [http://download.eclipse.org/oomph/updates Oomph update site].

=== Install Maven Integration (m2e) ===
In case you want to run a headless build locally in your workspace, you should install the [http://eclipse.org/m2e/ Maven Integration (m2e)], as GEF and GEF4 builds are based on Maven/Tycho.

=== Check out the code (Committers and Contributors) using EGit===
The complete source code of the GEF project (with the exception of the web-site) is hosted at [http://git.eclipse.org/c/?ofs=50 http://git.eclipse.org]:

* The GEF proper code base (Draw2d and GEF (MVC) 3.x as well as Zest 1.x ) can be found in the [http://git.eclipse.org/c/gef/org.eclipse.gef.git/ GEF Git repository]
* The [[GEF/GEF4 | GEF4]] provisional code base can be found in the [http://git.eclipse.org/c/gef/org.eclipse.gef4.git/ GEF4 Git repository]. 

To check out the code within your local workspace, perform the following steps:
# Copy the URI of the repository you want to clone (following the links provided above, the URIs are listed under the ''Clone'' section). Note that committers will have to use the ''ssh'' protocol URI, whereas consumers and contributors are encouraged to use the ''git'' protocol URI.
# Clone the Git repository
## Open the ''Git Repository Exploring Perspective'' (provided by EGit) within Eclipse, and from the toolbar of the ''Git Repositories Browser'' view select to ''Clone a Git Repository and add the clone to this view''. 
## If the repository URL was copied to clipboard before, the upcoming ''Clone Git Repository'' dialog should already provide the necessary entries for ''URI'', ''Host'', and ''Repository path'', so you may simple forward by pressing ''Next >''.
## Select the branches you want to clone from remote. The ''master'' branch is the one used for the current development stream. Development in maintenance releases is performed in respective maintenance branches. After having selected all branches of interest, press ''Next >'' to continue.
## Choose a local directory to store the cloned repository (the default will be located under your home directory) and select the ''Initial branch'' to check out.
# Checkout the projects
## Right-click the ''Working directory'' entry, located under the ''org.eclipse.gef'' (resp. ''org.eclipse.gef4'') repository within the ''Git Repositories Browser'' view and from the context menu select to ''Import Projects...''.
## In the upcoming ''Import Projects from Git Repository'' dialog, select to ''Import existing projects'' and press ''Next >''.
## Choose the projects you want to import (by default all are selected) and press ''Finish'' to conclude.

===Set up the Target Platform===
A target definition file is provided by the <code>org.eclipse.gef.target</code> (as well as the <code>org.eclipse.gef4.target</code>) project. To specify the target platform, simply open the respective target definition (e.g. ''MARS.target'') within the ''Target Editor'', let is fully resolve (i.e. wait until the ''Resolving Target Definition'' background task has finished and the installable units are listed under the respective ''Locations''), then choose to "Set as Target Platform'').

In case the target editor does not properly resolve the target definition, an invalid target cache may be the cause. In such cases, opening the target definition file with a text editor and incrementing the sequence number manually, will invalidate the cache when reopening it with the target editor again. After the cache has been invalidated, the sequence number can be restored.

=== Generate Xtext Artifacts ===
Parts of the GEF4 DOT code base ('org.eclipse.gef4.dot', 'org.eclipse.gef4.dot.ui') contain sources that are generated by Xtext. These generated sources are not contained in the Git repository and have to be generated locally within the development workspace. If you have installed Xtext in your IDE (see [[#Install Xtext|Install Xtext]]), you can manually trigger the Xtext artifact generation by selecting <code>Dot.xtext</code> within <code>org.eclipse.gef4.internal.dot.parser</code> package in the Package Explorer, and by choosing ''Run As -> Generate Xtext Artifacts'' from the context menu.

Alternatively you may execute a local Maven build (see [[#Running a headless build locally|Running a headless build locally]]. Make sure to refresh the ''org.eclipse.gef4.dot'' and ''org.eclipse.gef4.dot.ui'' projects in your workspace after having executed the local build (''Refresh'' from context menu on respective projects, or ''F5''), and make sure to clean your workspace afterwards (''Project -> Clean -> Clean all projects'').

===Set up PDE API Tooling ===
All production code GEF and GEF4 bundles (i.e. excluding doc and test bundles) are configured to have PDE API tooling enabled. It is used to ensure compliance of sources to the specified execution environments, as well as for proper handling of version numbering due to API changes (not in case of GEF4, where all API is still provisional). As PDE API tooling requires the definition of an API baseline you will see errors after having checked out the code ('An API baseline has not been set for the current workspace.').

For GEF, API-baselines are provided by the <code>org.eclipse.gef.baseline</code> project. You may define them by going to ''Preferences -> Plug-in Development -> API Baselines'', then choose to select "Add Baseline..." and point to the <code>plugins</code> sub-folder of an API baseline located in the baselines project (note that the dialog browses the file system instead of the workspace, so you will have to point into the respective folder in your local Git repository).

For GEF4, there are no API baselines defined yet, because all API is still provisional (and PDE API tooling does not consider provisional API). You will nevertheless see above mentioned errors after having checked out the code. They can be removed by going to ''Preferences -> Plug-in Development -> API Baselines'' and choosing ''Warning'' or ''Ignore'' as severity for the ''Missing API baseline'' option.

===Adjust Java and Plug-in Compiler Preferences (Discouraged access errors/warnings caused by provisional API)===
As all GEF4 API is currently released as '''provisional''', all GEF4 API package exports are guarded with the ''x-internal'' directive (see [[#Marking stable, provisional, and non-API | Marking stable, provisional, and non-API]] for details). Dependent on your workspace settings, this may lead to a lot of Java compiler warnings/errors, which result from discouraged API access. You may want to adjust your workspace-wide Java and Plug-in compiler preferences to get rid of them. 
* Go to "Preferences -> Java -> Compiler -> Warnings/Errors", then select the respective severity ("Warning", "Ignore") for the "Deprecated and restricted API -> Discouraged reference (access rule)" entry.
* Go to "Preferences -> Plug-in Development -> Compilers", then select the respective severity ("Warning", "Ignore") for the "References ->References to discouraged classes" entry.

== Starting an (Eclipse Application) runtime, resolving JavaFX runtime dependencies ==
When launching an Eclipse runtime that contains GEF4 bundles with JavaFX dependencies, the e(fx)clipse <code>org.eclipse.fx.javafx</code> bundle <code>org.eclipse.fx.osgi</code> fragment have to be included in the runtime configuration (they are already included in the GEF4 target). Also, <code>-Dosgi.framework.extensions=org.eclipse.fx.osgi</code> has to be added to the ''VM arguments'' in the runtime configuration's ''Arguments'' tab. If you are having problems with the e(fx)clipse runtime resolution you can add <code>-Defxclipse.osgi.hook.debug=true</code> to the ''VM arguments'' to enable debugging output. We noticed that e(fx)clipse does not seem to work correctly when running SWT on GTK 3 on older GTK versions. In this case, you can enforce SWT to use GTK 2 by setting the environment variable <code>SWT_GTK3=0</code> or adding <code>--launcher.GTK_version 2</code> to your eclipse.ini.

== Running a headless build locally ==
GEF (as well as [[GEF/GEF4 | GEF4]]) uses a Maven/Tycho-based build infrastructure. With the [http://eclipse.org/m2e/ Maven Integration] installed, the headless build that is executed by the [https://hudson.eclipse.org/hudson/job/gef-master/ gef-master] and [https://hudson.eclipse.org/hudson/job/gef4-master/ gef4-master] Hudson build jobs can also be executed in the local workspace. Make sure you have checked out all projects of a respective git repository (GEF and GEF4 are independent). Then easily run the build by right-clicking the <code>pom.xml</code> file located within the <code>org.eclipse.gef.releng</code> or <code>org.eclipse.gef4.releng</code> project respectively, and selecting 'Run As -> Maven build...'.

In the configuration wizard you have to specify the goals ("clean verify") and the profiles ("Mars.target") for the build. Note that without setting the target profile the build will not run successfully.

[[Image:GEF-ContributorGuide-Build-Locally-Main.png]]

You should select a Java-8 JVM in the "JRE" tab, to ensure that you run with a configuration comparable to that of the CI-server (hudson.eclipse.org). Otherwise your local build might behave differently compared to the continuous CI build. For example, javadoc errors are will not lead to a build failure when running with Java-7, while the build will fail if using Java-8 (as done in the CI server build jobs).

[[Image:GEF-ContributorGuide-Build-Locally-JRE.png]]

As a result of the build, an update-site will be created in the <code>target</code> sub-folder of the <code>org.eclipse.gef.repository</code> respectively <code>org.eclipse.gef4.repository</code> project. Please note that you need to have a JDK installed (and used by Tycho) rather than a JRE, because the Tycho builds rely on the availability of a javadoc executable for the generation of API documentation in the doc bundles.

== Creating a Contribution  ==
You can contribute to GEF either by producing a patch, or via GitHub. In either case, your contribution should be related to a corresponding Bugzilla entry (you can search for [http://bugs.eclipse.org/bugs/buglist.cgi?query_format=advanced;product=GEF existing bugs], or [https://bugs.eclipse.org/bugs/enter_bug.cgi?product=GEF file a new one]). 

We can easily consume your contribution (compare [https://wiki.eclipse.org/Development_Resources/Contributing_via_Git#Contributing_a_patch Contributing a Patch]), if:
* you have signed the Eclipse Contributor License Agreement (see [https://www.eclipse.org/legal/CLA.php Eclipse Foundation Contributor License Agreement]), and
* you have stated (in the corresponding Bugzilla entry) that the contribution complies to the Eclipse Foundation Certificate of Origin (see [http://www.eclipse.org/legal/CoO.php Eclipse Foundation Certificate of Origin]) and/or you have properly signed-off your GitHub Git commit.
 
If your contribution does not exceed the contribution limit (currently 1000 LOC) this will allow us to simply consume it. If your contribution was not developed from scratch or contains content from other authors, please indicate this on the related Bugzilla entry. As in cases where the contribution exceeds the limit, we will have to open a contribution questionnaire (and may have to ask for additional information via the related Bugzilla) to handle such cases (see [http://eclipse.org/legal/EclipseLegalProcessPoster.pdf Eclipse Legal Process]).

===Produce a Patch===
To contribute a patch, create a branch in your local Git repository for working on your changes, e.g. a fix for {{bug|321775}}:

 git checkout -b fix-321775

Test, fix, and commit until you're done. Run the Maven build to make sure everything works. Then create a patch including all commits on your branch against master, like this:

 git format-patch master --stdout > fix-321775.patch

Finally, attach your patch to the corresponding bug, in this case bug 321775.

===Fork via GitHub===
To contribute via GitHub, fork the GitHub repository you'd like to contribute to from [https://github.com/eclipse https://github.com/eclipse] (i.e. the [https://github.com/eclipse/gef GEF] or [https://github.com/eclipse/gef4 GEF4]. Commit, test, and push your contribution to your fork. When you're done, add a link to the Github commit you want to contribute to a comment in the corresponding bugzilla entry, e.g.:

  https://github.com/ujhelyiz/zest/commit/c1a69026477f0852727a2132233e9e61c14b4d8d

For details, see [[Development_Resources/Handling_Git_Contributions]].

==Commiting  code==

===Comments===
When committing code, the following format should be used:

  '[' ( <bug-id> | 'NONE' ) ']' <one-line-summary-or-single-line-commit-message> (  '(' 'CQ' <cq-number> ')' )?
  
  ( <wrapped-detailed-commit-message> )?

Examples:

  [355997] Add support for calculating bezier curve intersections. (CQ 5976)

  [NONE] Update target definition to Eclipse SDK 4.2.0.I20120222-0915.

Furthermore, the following constraints should be regarded:
* The bug id of the bug, which is used to track the changes should always be provided, or NONE to indicate that the changes are made without any directly related bug.
* The commit message should be specified using present tense, declaring why the changes were made. 
* If a commit message is longer than one short line, it should be formatted to have a short, one-line summary, a blank line, and a wrapped longer description (see [http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html].
* If the committer is not the contributor of the changes, the Git author field should be used to specify the full name of the contributor (see [[Development_Resources/Handling_Git_Contributions]]). In case the changes were approved by means of a contribution questionnaire, the CQ number should be specified in round brackets after the one line summary.

== Coding conventions == 

=== Marking stable, provisional, and non-API ===

According to the Eclipse [https://wiki.eclipse.org/Provisional_API_Guidelines Provisional API Guidelines] and the [https://wiki.eclipse.org/index.php/Naming_Conventions Naming Conventions], the following conventions are followed to differentiate between stable, provisional, and non-API (see also [https://bugs.eclipse.org/bugs/show_bug.cgi?id=438900 bug #438900]):

* Stable API: All stable API packages do not contain 'internal' in their package names and are exposed via 'Export-Package' in the plug-in MANIFEST.MF, unguarded by 'x-friends' or 'x-internal' directives.
* Provisional API: All provisional API packages do not contain 'internal' in their package names and are exposed via 'Export-Package' in the plug-in MANIFEST.MF, guarded by an 'x-internal' directive.
* Non-API: All non-API packages contain 'internal' in their package names , e.g. <code>org.eclipse.gef4.internal.geometry.utils</code>. These packages should only be exposed via 'Expose-Package' in the plug-in MANIFEST.MF, if this is guarded by an 'x-friends' directive.

Please note that for the Mars release, all of the GEF4 API will still be provisional (i.e. all API packages are provisional API packages). This will cause a lot of warnings/errors in your workspace, unless you follow the guidance given [[#Adjust Java and Plug-in Compiler Preferences (Discouraged access errors/warnings caused by provisional API)| Adjust Java and Plug-in Compiler Preferences]].

== Bugzilla conventions ==
When working with bugzillas, the following guidelines should be regarded.

=== Classifying Bugs ===
For GEF4, components are pretty fine-grained, so selection of a bugzilla component is usually sufficient to identify the part of the API that is concerned.

For Draw2d/GEF (MVC) 3.x this may not be sufficient. We thus use categories for this issue, which will be stated as a [<category_name>] prefix within the bugzilla's summary. The list of currently used categories is:

* General
** [TVT] - Translation Verification Tests

* Draw2d
** [GraphLayout]
** [Geometry] 
** [Text]

* GEF
** [Command]
** [DnD]
** [EditPart]
** [EditPolicy]
** [Palette]
** [Print]
** [Tool]

=== Resolving Policy ===
When resolving bugzillas, it should be stated how the bug is verified. Preferably this is a JUnit test. Alternatively, the bugzilla will say that the defect can be reproduced in the Logic example and you can demonstrate the fix working in the logic example (or other examples using GEF). If the bug is trivial or obvious and does not require a test, we can just state this in the Bugzilla too.

[[Category:GEF]]