Documentation/4.8/Developers/Tutorials/BundleModulesIntoExtension

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Overview

Extensions are packaged against a specific version of Slicer, to be distributed and available for a revision X of Slicer, extensions have to be build against that same revision of Slicer. Otherwise, an extension will be considered as incompatible.

1. If you are not familiar with the extension creation and contribution process, consider reading Step-by-step: How to create, publish and distribute an extension.

CMake variables

To create an extension, the following CMake variables should be defined:

CMake variable	Description	Mandatory
EXTENSION_NAME	Name of the extension
EXTENSION_HOMEPAGE	Url of the web page describing the extension
EXTENSION_CATEGORY	Extension category
EXTENSION_CONTRIBUTORS	Extension contributor specified as Firstname1 Lastname1 ([SubOrg1, ]Org1), Firstname2 Lastname2 ([SubOrg2, ]Org2)
EXTENSION_DESCRIPTION	One line describing what is the purpose of the extension
EXTENSION_ICONURL	Url to an icon (png, size 128x128 pixels)
EXTENSION_SCREENSHOTURLS	Space separated list of urls to images
EXTENSION_DEPENDS	List of extensions required to build this extension. Specify "NA" if there are no dependency.

List of partially supported CMake variables:

CMake variable	Description
EXTENSION_STATUS	Give people an idea what to expect from this code

Project layout

The code should be organized as illustrated below:

  MyExtension  <- - - - - - - - - - - - - - - - - - - - - - Top-level folder of the extension project
       |
       |-- CMakeLists.txt
       |
       |-- MyExtension.png
       |
       |-- MyCLIModule
       |        |
       |        |-- CMakeLists.txt
       |        |
       |        |-- MyCLIModule.cxx
       |        |
       |        |-- MyCLIModule.xml
       .        .
       .        .
       |
       |-- MyLoadableModule
                |
                |-- CMakeLists.txt
                |
                |-- qSlicerMyLoadableModuleModule.cxx
                |
                |-- qSlicerMyLoadableModuleModule.h
                .
                .

Top-level CMakeLists.txt

The top-level CMakeLists.txt could be organized as reported below:

cmake_minimum_required(VERSION 2.8.9)

#-----------------------------------------------------------------------------
# Extension meta-information <- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - EXTENSION SPECIFIC
set(EXTENSION_NAME MyExtension)  <- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - EXTENSION SPECIFIC
set(EXTENSION_HOMEPAGE "http://www.slicer.org/slicerWiki/index.php/Documentation/4.1/Extensions/${EXTENSION_NAME}")  <- - - - EXTENSION SPECIFIC
set(EXTENSION_CATEGORY "Examples")  <- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  EXTENSION SPECIFIC
set(EXTENSION_CONTRIBUTORS "Jean-Christophe Fillion-Robin (Kitware)")  <- - - - - - - - - - - - - - - - - - - - - - - - - - - EXTENSION SPECIFIC
set(EXTENSION_DESCRIPTION "This is an example of extension bundling a CLI, a loadable and a scripted module")  <- - - - - - - EXTENSION SPECIFIC
set(EXTENSION_ICONURL "http://viewvc.slicer.org/viewvc.cgi/Slicer4/trunk/Extensions/Testing/LoadableExtensionTemplate/Resources/Icons/LoadableExtensionTemplate.png?revision=19437&view=co")

#-----------------------------------------------------------------------------
find_package(Slicer REQUIRED)
include(${Slicer_USE_FILE})

#-----------------------------------------------------------------------------
add_subdirectory(MyCLIModule)
add_subdirectory(MyLoadableModule)
[...]

#-----------------------------------------------------------------------------
include(${Slicer_EXTENSION_CPACK})  <- - - - -  EXTENSION SPECIFIC

Possible tweak of Module level CMakeLists.txt

During the development process, it could be useful to be able to build each module against a given slicer build tree without having to build the complete extensions, to do so the CMakeLists.txt of each module could include find_package(Slicer REQUIRED).

For example, the CMakeLists.txt of MyCLIModule module that would be bundled into MyExtension could include the following code:

cmake_minimum_required(VERSION 2.8.9)

#-----------------------------------------------------------------------------
set(MODULE_NAME MyCLIModule) # Do not use 'project()'

#-----------------------------------------------------------------------------
find_package(Slicer REQUIRED)
include(${Slicer_USE_FILE})

[...]

Additional documentation

• Step-by-step: How to create, publish and distribute an extension
• AHM 2011 SlicerExtensions presentation
• Read FAQ