# Development/Extension Development

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## Introduction

LibreOffice has 3 kinds of extensions.

• If you are an extension developer, you can use several languages to develop LibreOffice extensions. Supported programming languages are Basic, Python, JavaScript, Java and BeanShell. For the higher level of integrity and possibilities you can use C++, Python and Java languages to develop UNO complements based extensions. They are bundled as .oxt files and can be shared on extensions.libreoffice.org.
Extensions are the preferred way for sysadmins to modify default settings. A guide for developing configuration extensions is available in PDF or ODT format. A sample OXT configuration extension accompanies the guide.
• There are also special Calc extensions known as Add-Ins that add spreadsheet functions to Calc. As a UNO components you can provide new implementations of existing functionality or specialized components like Calc Add-Ins, Add-Ons, DataPilots, Chart Add-Ins, or linguistic components: Spellchecker, Hyphenator or Thesaurus (see Add-Ins documentation).
• You can also pack extensions for additional Templates, Gallery and Autotexts. See the examples in the "Examples" section below.
• You may have noted that in some examples the templates are put in a folder named "templates", while in some other examples the templates are put in a folder named "template". Don't be confused by the names here. Both will work, provided that you specify the correct name you have used in the Paths.xcu file. Please note that in the Paths.xcu file, the "%origin%" as in "<node oor:name="%origin%/template" oor:op="fuse"/>" refers to the location of the extension after it has been installed (e.g. file:///<path-to-your-libreoffice-installation-or-config>/user/uno_packages/cache/uno_packages/lu168780135zflp.tmp_/<extenion_filename>.oxt). As such, the "template" as in "<node oor:name="%origin%/template" oor:op="fuse"/>" should be the path relative to the root of your un-zipped extension. This means that it if you put the actual templates in a folder named "my_tempaltes" when organizing the extension structure, then in Paths.xcu it should be: "<node oor:name="%origin%/my_templates" oor:op="fuse"/>".
• Also, note that the "Template" as in "<node oor:name="Template" oor:op="fuse" oor:mandatory="true">" shown in the Paths.xcu file indicates that this path setting is for the "Template" category, which is defined in unotools/source/config/pathoptions.cxx:170 (together with Addin, AutoCorrect, AutoText, Dictionary, Gallery etc).

## Resources

In an effort to not duplicate information, you can refer to OpenOffice's documentation. They are still largely compatible, but extra check should be performed since LibreOffice is moving forwards rapidly (see Compatibility notes below).

Current resources are currently being consolidated on the LibreOffice help pages.

Before you can start, you need to install the SDK.

### Examples

To jump-start development, you can take a look at the source of existing extensions.

Examples:

#### Java

• Starter Extension Starter extension to be used as a base for own extensions
• Sidebar Extension Similiar to starter extension, but for creating an own Sidebar Deck
• NOA-libre is an object-oriented lightweight Java wrapper around LibreOffice UNO API, providing higher-level abstraction of many UNO interfaces.
• UNOHelper offers helper functions for working with the the UNO API. It wraps commonly used functions from the UNO API for easier use.
• WollMux is a large Java Extension with enhanced template, form, and autotext functionality.

#### Eclipse Plugin

TDF offers the Eclipse Plugin LOEclipse which helps with developing LibreOffice extensions/components in Java. You can find it on the Eclipse Marketplace.

#### C++

The LibreOffice source code also has a collection of SDK examples.

#### Non-coding Examples

• Andreas Mantke's github extensionbook repository contains a collection of non-coding examples explaining how to package a set of colors, templates, auto-text and galleries into an extension.
• Kevin Suo's github lo_l10n_templates repository is an example of how to make a template-set as a LibreOffice extension and make it localized.

## Compatibility notes

The LibreOffice developers are conservative when it comes to changes to the public (UNO) API and thus, most extensions written for OpenOffice.org or Apache OpenOffice will still work with LibreOffice. If changes happen, they are noted in the ReleaseNotes (API changes in 4.2, 4.1 and 4.0).

• The OpenOffice.org-minimal-version dependency states that an extension works in the specified OpenOffice.org versions as well as in LibreOffice versions that correspond to at least the specified OpenOffice.org reference version. All LibreOffice versions up to 4.2.3 report that they correspond to OpenOffice.org reference version 3.4, while LibreOffice versions since 4.2.4 report that they correspond to OpenOffice.org reference version 4.1. Using this dependency, the extension declares that it only uses features found in the specified OpenOffice.org reference version (and that it consequently works across all the products, not only for OpenOffice.org itself).
• If an extension makes use of features specific to LibreOffice, starting with LibreOffice 3.5 it can specify a new dependency LibreOffice-minimal-version with namespace http://libreoffice.org/extensions/description/2011. Its required value attribute (without namespace) specifies the minimally supported LibreOffice version; it should not contain a micro version number, and it should not be less than 3.5.
The generally required name attribute (with namespace http://openoffice.org/extensions/description/2006) should be “LibreOffice version” (where version is the given version value).
Examples may be found in core/tree/desktop/test/deployment/dependencies: loversion35.oxt or loversion36.oxt.
• If an extension is intended for a specific version of LibreOffice, starting with LibreOffice 7.0 it can specify a new dependency LibreOffice-maximal-version with namespace http://libreoffice.org/extensions/description/2011 in addition to the dependency LibreOffice-minimal-version. This should be needed very rarely.