Discussion of a Legending Spec for Mapnik

Should be configured with XML or a python class.

#536 tracks progress on this feature.

Possible Example

XML

<Legend>
<Title breakline=true stroke-width="1" stroke="black">Education</title>
<SubTitle> Level of Education Among Population Over Age 20</Subtitle>
<Item>
<Symbolizer>
<CssParameter name="stroke">white</CssParameter>
<CssParameter name="stroke-width">.5</CssParameter>
<CssParameter name="fill">#93A462</CssParameter>
<ItemText face_name="DejaVu Sans Bold" size="10" fill="black">Highest</ItemText>
</Item>
....
</Legend>

Python

Feature Wishlist

Layer symbolization using representative feature geometry

Default behavior would will be to use, for example, a filled rectangle to represent polygon geometries (like the example graphic above)

But an optional filter could be applied to direct the legend renderer to use a specific feature geometry (scaled to fit the legend layout) as the symbol

That would look something like:

Syntax might look like:

<Item>
<Filter>[id] = 1</Filter>
<Symbolizer>
...

# or, more simplistically choose a random feature
<Item use_feature="true">
<Symbolizer>
...

See also

Lars Ahlzen has written a Python script for TopOSM which creates HTML snippets with images from a Mapnik style file: http://wiki.openstreetmap.org/wiki/TopOSM#Map_legend