Book Image

Building Mapping Applications with QGIS

By : Erik Westra
Book Image

Building Mapping Applications with QGIS

By: Erik Westra

Overview of this book

Table of Contents (16 chapters)
Building Mapping Applications with QGIS
About the Author
About the Reviewers
Free Chapter
Getting Started with QGIS


In this chapter, we designed and implemented a simple but complete turnkey mapping application using PyQGIS. In doing this, we learned how a wrapper script can be used to keep platform-specific settings out of your Python program. We also saw how we can define our application's UI in a separate module even if we don't use Qt Designer to create our user interface templates.

We learned how to use the "PAL" labeling engine built into QGIS to display a label for each feature within a vector map layer. We saw that a QgsRuleBasedRendererV2 object can be used to show or hide certain features based on the map's scale factor, and that data-defined properties allow us to calculate values such as the label's font size; we also saw how the CASE...WHEN expression can be used to calculate data-defined properties in sophisticated ways.

Finally, we saw how to implement Google Maps style panning and zooming within a mapping application.

In the next chapter, we will learn about some of the more advanced...