I am trying to develop a standalone application using pyqgis but I have no clue on where to start and where to write the code to make it happen so if anyone can provide me a tutorial to getting started, it'll be a huge benefit for me. Thanks.
[GIS] Developing standalone gis applications using pyqgis
pyqgisqgisstandalone
Related Solutions
You have to start the Qt event loop using:
app.exec_()
I would remove QgsApplication.exitQgis(). It should ideally be handled in a slot that is connected to lastWindowClosed() signal of the application.
If you have installed QGIS via OSGeo4W, I suggest you to follow this work flow (I've just tested it on Windows 7):
Open the OSGeo4W Shell.
Start->All programs->OSGeo4W->OSGeo4W Shell.Set environment variables. My preferred way is to execute this bat file (updated 2016.11.03: this bat file) from the OSGeo4W Shell. As you can see, the file sets environment variables in this way:
set PYTHONPATH=%OSGEO4W_ROOT%\\apps\\qgis\\python set PATH=%OSGEO4W_ROOT%\\apps\\qgis\\bin;%PATH%Of course, you need to check by yourself that those paths exist in your OS and adjust them if necessary.
So, download the .bat file and execute it by accessing it from the OSGeo4W Shell and pressing ENTER.
Import PyQGIS libraries by one of the following methods:
a. Enter the Python interpreter. Run
pythonin the OSGeo4W Shell and import the libraries manually.
b. Execute a Python script. Run
python my_pyqgis_script.pyin the OSGeo4W Shell. I'd start with a very simple one.
The work flow was posted (in Spanish) several years ago in GeoTux and still works. As you can see, I do not include environment variables in the Python script, but set them in the OSGeo4W Shell.
Best Answer
The best resource for this is the official documentation in the pyqgis cookbook
Also a very useful resource is the API documentation although aimed at C++ code and therefore not always applicable just like that it is very good for finding hints.
You can also search for existing python plugins and have a look at how they solved similar problems.