Plugins

Important

Plugins is an experimental feature! The API may change.

We welcome you to try and provide your feedback.

Plugins allow you to extend the functionality of Gaphor beyond the features provided in the standard distributions. In particular, plugins can be helpful if you install the binary distributions available on the download page.

Gaphor can be extended via entry points in several ways:

1. Application (global) services (gaphor.appservices)

2. Session specific services (gaphor.services)

3. Modeling languages (gaphor.modelinglanguages)

4. (Sub)command line parsers (gaphor.argparsers)

5. Indirectly loaded modules (gaphor.modules), mainly for UI components

The default location for plugins is $HOME/.local/gaphor/plugins-2 ($USER/.local/gaphor/plugins-2 on Windows). This location can be changed by setting the environment variable GAPHOR_PLUGIN_PATH and point to a directory.

Install a plugin

At this moment Gaphor does not have functionality bundled to install and maintain plugins. To install a plugin, use pip from a Python installation on your computer. On macOS and Linux, that should be easy, on Windows you may need to install Python separately from python.org or the Windows Store.

Important

1. Since plugins are installed with your system Python version, it’s important that plugins are pure Python and do not contain compiled C code.

2. If you use Gaphor installed as Flatpak, you need to grant Gaphor access to user files (filesystem=home), so Gaphor can find files in your .local folder. You can use FlatSeal to change permissions of Flatpaks.

For example: to install the Hello World plugin on Linux and macOS, enter:

pip install --target $HOME/.local/gaphor/plugins-2 git+https://github.com/gaphor/gaphor_plugin_helloworld.git

Then start Gaphor as you normally would. A new Hello World entry has been added to the tools menu ( → Tools → Hello World).

Create your own plugin

If you want to write a plugin yourself, you can familiarize yourself with Gaphor’s design principles, service oriented architecture (includes a plugin example), and event driven framework.

Example plugin

You can have a look at the Hello World plugin available on GitHub for an example of how to create your own plugin.

The pyproject.toml file contains a plugin:

[tool.poetry.plugins."gaphor.services"]
"helloworld" = "gaphor_helloworld_plugin:HelloWorldPlugin"

This refers to the class HelloWorldPlugin in package/module gaphor_plugins_helloworld.

Here is a stripped version of the hello world plugin:

from gaphor.abc import Service, ActionProvider
from gaphor.core import _, action

class HelloWorldPlugin(Service, ActionProvider):     # 1.

    def __init__(self, tools_menu):                  # 2.
        self.tools_menu = tools_menu
        tools_menu.add_actions(self)                 # 3.

    def shutdown(self):                              # 4.
        self.tools_menu.remove_actions(self)

    @action(                                         # 5.
        name="helloworld",
        label=_("Hello world"),
        tooltip=_("Every application…"),
    )
    def helloworld_action(self):
        main_window = self.main_window
        ...  # gtk code left out

1. As stated before, a plugin should implement the Service interface. It also implements ActionProvider, saying it has some actions to be performed by the user.

2. The menu entry will be part of the “Tools” extension menu. This extension point is created as a service. Other services can also be passed as dependencies. Services can get references to other services by defining them as arguments of the constructor.

3. All action defined in this service are registered.

4. Each service has a shutdown() method. This allows the service to perform some cleanup when it’s shut down.

5. The action that can be invoked. The action is defined and will be picked up by add_actions() method (see 3.)