jpsacha / sbt-imagej   2.1.0

GNU General Public License v3.0 only GitHub

sbt-imagej is an SBT (Simmple Build Tool) plugin that that helps with development of ImageJ plugins

Scala versions: 2.12 2.10
sbt plugins: 1.0 0.13


sbt-imagej is an SBT (Simple Build Tool) plugin that that helps with development of ImageJ plugins (those are different than SBT plugins). It works for Scala as well as Java, or mix of both.

The main task is ijRun it packages the ImageJ plugin and helps test the plugin from within ImageJ:

  1. Builds your ImageJ plugin and packages it as jar.
  2. Creates directory structure expected by ImageJ runtime.
  3. Copies the plugin jar to ImageJ plugins directory, along with all dependencies.
  4. Starts ImageJ instance that is aware of the new plugin location, so you can interactively test your plugin from within ImageJ.

The other task ijPrepareRun is intended for integration with IDEs, like IntelliJ IDEA and Eclipse. See also blog post Developing ImageJ plugins with SBT using sbt-imagej.

sbt-imagej requires SBT 1.0 or newer.


Add sbt-imagej as a dependency in project/imagej.sbt:

addSbtPlugin("net.sf.ij-plugins" % "sbt-imagej" % "2.1.0")

Once added to the project the plugin will be enabled by default.

Now you'll have a new ijRun task which will compile your project, pack your class files and resources in a jar, copy that jar and dependencies to local ImageJ's plugins directory, and run ImageJ

> ijRun

There is also a task that only copies the jar and dependencies to to the plugins directory

> ijPrepareRun

It is useful if you want to have your own run configuration, for instance executed by your IDE.


There are a couple of settings you can use to customize sbt-imagej plugins:

  • ijRuntimeSubDir - Location of ImageJ runtime directory relative to base directory. Default value is sandbox.
  • ijPluginsSubDir - Subdirectory of the plugins directory, where all jars will be copied. Default is jars.
  • ijExclusions - List of regex expressions that match JARs that will be excluded from the plugins directory. Default excludes ImageJ jar, source jars, and javadoc/scaladoc jars.
  • ijCleanBeforePrepareRun - If true the plugins directory will be cleaned (deleted) before it is populated by ijPrepareRun task. This is useful if jar names change during build, for instance, due to versioning. If old jars with different names will not be removed ImageJ will complain about duplicate plugins. Default value is false (for safety).

Consider example settings:

ijRuntimeSubDir := "sandbox"
ijPluginsSubDir := "my-plugin"
ijExclusions    += """some\.jar"""

This will set ImageJ runtime directory to sandbox and directory where your plugins will be copied to sandbox/plugins/my-plugin. Additionally exclude the some.jar from being copied to that directory. Note that for exclusions we used += rather than := this mean that we want to add one more exclusion to existing default exclusions, Using := would disable default exclusions.

You can use ijPluginsDir settings key to see full path to plugins subdirectory, where all jars will be copied. ijPluginsDir is intended to be read-only. It can be used, for instance, in cleanFiles += ijPluginsDir.value. By default, it is computed from ijPluginsSubDir and ijRuntimeSubDir. You should not reassign it.

Multi-Module Projects

If you are using a multi-module projects and would like to include dependent project jars in the plugins directory you need to take extra steps. When a SBT creates a classpath from dependent projects it exports a directory containing its resources and compiled class files, but not the actual jar produced by that project. If instead you want to export packaged jars, you need to use SBT option:

exportsJars := true

This is a standard SBT option. You need to add exportsJars := true to every dependent projects in your build. (I know it looks tedious, if there is a better solution please let me know).

Example Project

You can find example project in sub-directory [example]. It contains a simple project with with two ImageJ plugins.

Tips and Tricks

Extend clean to remove content created by ijRun or ijPrepareRun

You can make the regular clean command to remove extra content by adding directory to SBT setting cleanFiles

cleanFiles += ijPluginsDir.value

Copy additional files to plugins directory when ijPrepareRun is executed

Sometimes you want to copy some extra files to plugins directory. You can extend ijPrepareRun to do the copy or any other tasks:

ijPrepareRun := ijPrepareRun.value ++ {
  // Files you want to copy
  val srcFiles = Seq(
  val destDir = ijPluginsDir.value
  val destFiles = => destDir / f.getName)
  srcFiles zip destFiles.foreach{ case (src, dest) => IO.copyFile(src, dest) }
  // The last statement here should return the collection of copied files

Running using SBT

  1. Open command prompt
  2. Change directory to one containing this project
  3. Execute command sbt ijRun

Running SBT tasks at part of IntelliJ IDEA build

IntelliJ IDEA, with Scala plugin, can directly load SBT projects. You can then execute sbt tasks to build and copy needed jars to run your plugins in ImageJ.

Option 1: Run ijRun task as "Run Configuration"

  1. From the menu select "Run" > "Edit Configurations..."
  2. Click + (add new configuration) and select "sbt Task" as configuration type
  3. Give the configuration a name, say "ImageJ"
  4. Under "Tasks" type ijRun
  5. Make sure that working directory points to your module directory

Now you have new run configuration that will build your code, package jars, and start ImageJ with your plugins.

The downside of this method is that IntelliJ will not let you debug you code if you start it this way.

Option 2: Add ijPrepareRun to a typical application run configuration

The idea is to create a regular application run configuration and execute sbt ijPrepareRun to setup runtime directories:

  1. From the menu select "Run" > "Edit Configurations..."
  2. Click + (add new configuration) and select "Application" as configuration type
  3. Give you configuration a name, say "ImageJ"
  4. In "Main class:" type ij.ImageJ
  5. In "Working directory:" select subdirectory "sandbox" of your module directory (or a directory you defined in ijRuntimeSubDir)
  6. Select relevant project module.
  7. In "Before lunch:" select + and then select "Run External Tool"
  8. In "External Tool" window select + to define how to execute sbt ijPrepareRun
  9. Give the external toll configuration some name.
  10. In "Program:" type sbt
  11. In "Arguments:" type ijPrepareRun
  12. In "Working directory:" select your module directory
  13. Click "OK" a couple of times to close dialogs

Now you have definition of an application run configuration that will run ImageJ, before the run SBT will be called to prepare plugin jars and copy them to plugins subdirectory.


Copyright (c) 2013-2018 Jarek Sacha

Published under GPLv3, see LICENSE file.