Cascadenik

Cascadenik implements cascading stylesheets for Mapnik.

It’s an abstraction layer and preprocessor that converts special, CSS-like syntax into Mapnik-compatible style definitions. It’s easier to write complex style rules using the alternative syntax, because it allows for separation of symbolizers and provides a mechanism for inheritance.

Cascadenik supports many of Mapnik’s features in a simple declarative form:

/* Define a few colors */
@black: #000;
@orange: #f90;

/* Start with a white background */
Map
{
    map-bgcolor: #fff;
}

/* Draw roads as orange lines */
#roads
{
    /* Usually, 3px wide */
    line-width: 3;
    line-color: @orange;
    
    /* Make the important ones wider */
    &[kind=major] { line-width: 4 }
    &[kind=highway] { line-width: 5 }
    
    /* Add the road names in black */
    name
    {
        text-placement: line;
        text-face-name: "DejaVu Sans Book";
        text-fill: @black;
        text-size: 12;
    }
}

See more examples at https://github.com/mapnik/Cascadenik/wiki/Examples.

Usage

See INSTALL.md for installation instructions.

See the doc/ folder for more usage examples.

Unroll the rules in example.mss and show their cascade order:

% cascadenik-style.py example.mss > example-ordered-unrolled.mss

Compile example.mml into a Mapnik-suitable XML file:

% cascadenik-compile.py example.mml example-compiled.xml

Render a MML file directly to an image using nik2img.py:

% nik2img.py example.mml example.png