Book Image

QGIS Python Programming Cookbook, Second Edition - Second Edition

By : Joel Lawhead
Book Image

QGIS Python Programming Cookbook, Second Edition - Second Edition

By: Joel Lawhead

Overview of this book

QGIS is a desktop geographic information system that facilitates data viewing, editing, and analysis. Paired with the most efficient scripting language—Python, we can write effective scripts that extend the core functionality of QGIS. Based on version QGIS 2.18, this book will teach you how to write Python code that works with spatial data to automate geoprocessing tasks in QGIS. It will cover topics such as querying and editing vector data and using raster data. You will also learn to create, edit, and optimize a vector layer for faster queries, reproject a vector layer, reduce the number of vertices in a vector layer without losing critical data, and convert a raster to a vector. Following this, you will work through recipes that will help you compose static maps, create heavily customized maps, and add specialized labels and annotations. As well as this, we’ll also share a few tips and tricks based on different aspects of QGIS.
Table of Contents (16 chapters)
QGIS Python Programming Cookbook - Second Edition
About the Author
About the Reviewer
Customer Feedback

Using an outline for font markers

Font markers open up broad possibilities for icons, but a single-color shape can be hard to see across a varied map background. Recently, QGIS added the ability to place outlines around font marker symbols. In this recipe, we'll use font marker symbol methods to place an outline around the symbol to give it contrast and, therefore, visibility on any type of background.

Getting ready

Download the following zipped shapefile. Extract it and place it in a directory named ms in your qgis_data directory:

How to do it...

This recipe will load a layer from a shapefile, set up a font marker symbol, put an outline on it, and then add it to the layer. We'll use a simple text character, an @ sign, as our font marker to keep things simple:

  1. First, we need to import the QtGUI library, so we can work with color objects:

            from PyQt4.QtGui import * 
  2. Now, we create a path string to our shapefile...