Eclipse software is an Eclipse Foundation project, developed and organized into a set of software sub-projects, to develop an open source software production environment that is open-ended, universal and versatile, relying mainly on Java.
As one of the great success stories of Open Source, Eclipse has become a standard in the development software market, built in by leading software publishers as well as service companies.
You can develop a plugin for QGis with a simple text editor, but if you want to have a real development environment, allowing you to quickly debug your scripts, Eclipse is the best solution.
Where to start?
You must download and install Eclipse AND the plugin PyDev .
To download the latest version of Eclipse :
Run the installation file, selecting the installation “Eclipse IDE for Java Developers”
Once the installation is complete, Eclipse starts. Then you must install the PyDev plugin for Eclipse.
Go to the menu Help-> Install New software
Go to “Work with” and click Add
Go to name and type PyDev and in location the download site address: http://pydev.org/updates , and then click OK
Check the box PyDev, then Next and complete the plugin installation.
Once finished, you must restart Eclipse. You must define the Python interpreter to use:
Go to the menu Windows-> Preferences
In the left window, search for the item PyDev -> Interpreters -> Python Interpreter then click on New
Re-enter PyQGIS as name and point to the file python.ex e of your QGis installation. It is located in its bin directory.
When you click OK, the setup programme researches automatically all the available Python libraries to be added. If you let this happen, you’re going straight to conflicting libraries. You have to fill in these libraries manually to make sure there is no contradiction.
A warning message appears telling you that no libraries have been specified. Click on Proceed anyway.
Now, the most boring part of the installation. Be as patient as possible…
We will go back and forth between Eclipse and QGis to fill in all the necessary libraries.
For each Path spotted in QGis , you will have to click on the button New Folder of Eclipse and point to the directory concerned:
In QGis we will use the Python console. Open it and simply type qgis . You will get back the PyQGIS API path.
Use your insight to decode the answer, knowing that it fits your QGis installation. In this example the beginning is Programs / QgisEssen. Ignore the /./ as well as the last element. Indeed, what you need to fill in Eclipse this last element directory.
In Eclipse click New Folder and in the window that pops up, point directory
Click OK. You will see the directory displayed in the list of PYTHONPATH System
Right! But the hardest remains to be done. Type in the Python console
You will have something like this
For each path element you will have to repeat what we have done for the PyQGIS API, except for items you are sure do not interfere with your development, ie those that do not match your username, those that start with \\ Users \ or those which correspond to software environments other than QGis (in this example the path starting with \\ PCI Geomatics).
Once this is done for all paths, it’s not over! It remains to inform the QGis dlls.
In the Eclipse Preferences window, click the Environment tab
Click on New and in the window that opens type PATH in Name and in Value you will need to enter the list of QGis directories containing binary files, separated by; .
On Windows, take the following line and change the version of QGis to match the version installed on your computer:
Brighton C: \ Program Files \ QGIS; C: \ Program Files \ QGIS
Brighton \ bin; C: \ Program Files \ QGIS Brighton \ apps \ qgis \ bin; C: \ Program
Brighton Files \ QGIS \ apps \ Python27 \ DLLs
The configuration of Eclipse is complete!!
How to debug Python scripts in QGis?
Both QGIS and Eclipse must be configured for debugging so that both software can communicate. Eclipse binds to QGIS to give you an overview of the Python scripts running in QGIS. This approach allows you to run scripts in a controlled manner, suspend execution while you inspect the program for bugs when and where they occur.
When you launch a script in QGis, it is hand over to Eclipse to execute the code, which in turn is returned to QGis.
So we have to configure QGis to send the stream to Eclipse and Eclipse to return the results to QGis.
In this step we will add two plugins to QGIS, which allow Eclipse to communicate with QGIS. A plugin, Plugin Reloader, allows you to reload a QGIS plugin into the memory without restarting QGIS, to run the tests faster. The second plugin, Remote Debug, links QGIS to Eclipse.
Remote Debug is an experimental plugin, so you need to make sure the experimental plugins are visible in the list of available QGIS Plugin Manager plugins.
Install both plugins. Take advantage of the opportunity to install, as well, the HelloWorldPlugin, which will be helpful to test your configuration. Note the plugin’s location:
Go to the menu File-> New-> Project
Select General then Project and click on Next
Name the project, for example, to test the operation, HelloWorld Project , then click on the button Finish .
Select the project you just created, then right-click and New -> Folder
In the window New Folder which pops up, click on the button Advanced
Check the box “Link to alternate location (Linked Folder)” Then with the button browse point to the plugin directory to debug, in our example HelloWorld , in the directory that you checked during its installation.
To test the configuration, we will place a breakpoint in the script code HelloWorld , launch it in QGis , verify the code is on stop in Eclipse , restart execution in Eclipse and see the window appearing in QGis .
To set the breakpoint:
In Eclipse, open the HelloWorld.py file by double-clicking on it.
Go to the menu Window -> Perspective -> Open Perspective -> Other …
In the new window select debug and click on OK
The “perspective” Debug type is taken by Eclipse
Look for the first line of the plugin (def hello_world (self) 🙂 and double-click to the left of the line number to place a breakpoint (green bug)
From the PyDev menu, select Start Debug Server.
Debug Server at port: 5678
In the console (bellow the Eclipse window).
Now, go to QGis . In the Extensions menu click on Remote Debug -> Remote Debug
The Remote Debugger window opens. A last configuration is necessary.
Be sure that Debugger is placed on PyDev (Eclipse). In PyDevd path, as its name suggests, indicate where the file pydevd.py is located.
The easiest way is to search the Windows file manager and copy paste the path of that file. You only have to perform this operation the first time you use Remote Debugger.
Once done, click Connect, the window closes and a message appears in QGis indicating you: Python Debugging Active .
Launch the HeloWorld plugin from the menu Extension -> HelloWorld -> HelloWorld.
This, usually, results in displaying a message window with the text Hello World . But here, nothing happens.
Go to Eclipse .
You will verify that the line with the breakpoint is highlighted. This means that the execution of the script is stopped at this point.
To restart the execution, go to the menu Run-> Restart
Go to QGis. The Hello World window has appeared!
The configuration of your development environment is complete.