Plugin development doc

doc/plugin_development.md

+# Developing a plugin for sakia
+
+## Prepare dev environment
+
+Follow the doc file [Install for developers](https://github.com/duniter/sakia/doc/install_for_developers.md).
+You can use the same pyenv environment to develop your plugin.
+
+## Plugin structure
+
+The plugin source code should follow the structure below :
+
+```
+/
+   [plugin_pkg_name]/
+      images/                # The directory containing images used in the widget
+         images.qrc          # The qt resources .qrc file describing available images
+         [image1.png]        # The list of images
+         [image2.png]
+      __init__.py            # The __init__ file of the plugin
+      [script_1.py]          # Some scripts imported in the __init__ file
+      [script_2.py]
+      [ui_file.ui]           # ui files designed using QtDesigner
+```
+
+The `__init__.py` file must set the following global constants :
+
+```python
+PLUGIN_NAME = "Title of the plugin"
+PLUGIN_DESCRIPTION = "Description of the plugin"
+PLUGIN_VERSION = "0.1"
+```
+
+The function below must be present in the `__init__.py` file to initialize the plugin on Sakia startup :
+
+```python
+
+def plugin_exec(app, main_window):
+    """
+    :param sakia.app.Application app:
+    :param sakia.gui.main_window.controller.MainWindowController main_window:
+    """
+    # Place your init code here
+    pass
+```icons
+
+## Building your plugin
+
+To build the plugin, you need :
+
+### To generate resources (images, qrc, ...)
+
+Generating resources uses [pyrcc5](http://pyqt.sourceforge.net/Docs/PyQt5/resources.html).
+To help you generate your resources, you should copy the `gen_resources.py` file from sakia sources and configure the
+ variable `gen_resources`. Replace `'src'` by the name of your plugin package.
+
+### To import your resources in your code
+
+The generation of the resources build the following python files :
+
+ - `filename.ui` -> `filename_uic.py`
+ - `filename.qrc` -> `filename_rc.py`
+
+The `filename_uic.py` file should be imported in the file using the designed widget. See the
+[dialog of the example plugin](https://github.com/Insoleet/sakia-plugin-example/blob/master/plugin_example/main_dialog.py)
+
+The `filename_rc.py` file should be imported in the `__init__.py` file, on the last line. See the
+[__init__.py of the example plugin](https://github.com/Insoleet/sakia-plugin-example/blob/master/plugin_example/__init__.py#L28)
+
+### To generate your plugin
+
+To generate your plugin, you must zip everything (generated resources) in a zip file respecting the structure below :
+
+```
+[plugin_name].zip\
+    [plugin_name]\
+        __init__.py
+        [generated files...]
+```
+
+The [setup.py](https://github.com/Insoleet/sakia-plugin-example/blob/master/setup.py) file from the
+example plugin is available to help you generate correctly the plugin.
+