MapGenerator revisited

Now that we have examined the Python interface to Mapnik, let's use this knowledge to take a closer look at the mapGenerator.py module used in Chapter 7, Working with Spatial Data. As well as being a more comprehensive example of creating maps programmatically, the mapGenerator.py module suggests ways in which you can write your own wrapper around Mapnik to simplify the creation of a map using Python code.

The MapGenerator interface

The mapGenerator.py module defines just one function, generateMap(), which allows you to create a simple map which is stored in a temporary file on disk. The method signature for the generateMap() function looks like this:

def generateMap(datasource, minX, minY, maxX, maxY,
                mapWidth, mapHeight,
                hiliteExpr=None, background="#8080a0",
                hiliteLine="#000000", hiliteFill="#408000",
                normalLine="#404040", normalFill="#a0a0a0",
                points=None)

The parameters are as follows...