Book Image

QGIS Python Programming Cookbook

Book Image

QGIS Python Programming Cookbook

Overview of this book

Table of Contents (16 chapters)
QGIS Python Programming Cookbook
About the Author
About the Reviewers

Changing map layer transparency

Map layer transparency allows you to change the opacity of a layer, so the items behind it are visible to some degree. A common technique is to make a vector layer polygon partially transparent in order to allow the underlying imagery or elevation data to add texture to the data.

Getting ready

In a directory called ms, in your qgis_data directory, download and extract the following shapefile from

How to do it...

The process is extremely simple. Transparency is just a method:

  1. First, we load the shapefile layer:

    lyr = QgsVectorLayer("/Users/joellawhead/qgis_data/ms/mississippi.shp", "Mississippi", "ogr")
  2. Next, we set the layer's transparency to 50 percent:

  3. Finally, we add this layer to the map:


How it works...

If you set the transparency to 100 percent, the layer is completely opaque. If you set it to 0, the layer becomes completely...