Writing a Processing plugin
Depending on the kind of plugin that you are going to develop, it might be better
option to add its functionality as a Processing algorithm (or a set of them).
That would provide a better integration within QGIS, additional functionality (since
it can be run in the components of Processing, such as the modeler or the batch
processing interface), and a quicker development time (since Processing will take of
a large part of the work).
This document describes how to create a new plugin that adds its functionality as
There are two main mechanisms for doing that:
- Creating a plugin that adds an algorithm provider: This options is more complex,
but provides more flexibility
- Creating a plugin that contains a set of processing scripts: The simplest solution,
you just need a set of Processing script files.
To create an algorithm provider, follow these steps:
- Install the Plugin Builder plugin
- Create a new plugin using the Plugin Builder. When the Plugin Builder asks you for
the template to use, select “Processing provider”.
- The created plugin contains a provider with a single algorithm. Both the provider
file and the algorithm file are fully commented and contain information about how to
modify the provider and add additional algorithms. Refer to them for more information.
To create a set of processing scripts, follow these steps:
- Create your scripts as described in the PyQGIS cookbook. All the scripts that you want
to add, you should have them available in the Processing toolbox.
- In the Scripts/Tools group in the Processing toolbox, double-click on the Create
script collection plugin item. You will see a window where you should select the scripts
to add to the plugin (from the set of available ones in the toolbox), and some additional
information needed for the plugin metadata.
- Click on OK and the plugin will be created.
- You can add additional scripts to the plugin by adding scripts python files to the scripts
folder in the resulting plugin folder.