Graphics Reference
In-Depth Information
Summary
In this chapter, we became familiar with QGIS and the various ways in which it can be
used as a Python geospatial development system. We installed and explored the QGIS ap-
plication itself, and then looked at how Python can be used with QGIS. We saw how QGIS
uses data sources, map layers, maps, and projects to organize and work with geospatial
data. Next, we examined the three ways in which you can use Python and QGIS: by typing
commands into the Python Console, by writing a Python plugin or by writing an external
application that makes use of the QGIS Python API.
We then looked at the extensive set of Python libraries that come with QGIS, called
PyQGIS, which you can use for geospatial development. We saw how to use the QGIS
Python Console to directly manipulate the QGIS project, add layers, zoom in and out,
change options, and so on.
Next up, we downloaded and examined a QGIS Python plugin. In doing this, we learned
that QGIS plugins are simply Python packages installed in a hidden directory named
.qgis2
(or
.qgis
) within your home or user directory. A plugin makes use of the Qt lib-
rary to define and build resources such as user interface templates.
Finally, we saw how we can write external Python applications that load the PyQGIS lib-
raries from within the QGIS system, and then use those libraries within a larger PyQt ap-
plication.
In the next chapter, we will explore the QGIS Python Console in more detail, and use it to
become more familiar with the PyQGIS library, and also see how we can use it within our
own Python geospatial development projects.
