Tools to help creating legends (or key map) for mapnik or Openstreetmap based maps.
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Set of tools to create a legend (or mapkey) of an Openstreetmap Map with Mapnik. The core of the project is RenderLegendElement.py that rendered a small pic with given tags, size and shape against a mapnik style sheet. It make use of the osm datasource in mapnik, and does not need any sql database. Simple and easy ! Mapnik 0.7.2 dev branch is required. => svn co http://svn.mapnik.org/branches/0.7.2-dev/ mapnik-0.7.2 Usage exemple: Put RenderLegendElement.py in the same directory as osm.xml, then: $python >>>from RenderLegendElement import renderLegendElement >>>renderLegendElement("osm.xml", 'line',["[highway]='primary'","[bridge]='yes'"],18, 50, 'output.png') That's it! RenderLegendElement.py: Input: _ mapnik stylesheet _ elementType: point, line, square, rectangle, pointtext, linetext, lineshield, squaretext, rectangletext, squarepoint, smallline _ tagList python style ["[key1]='value1'", "[key2]='value2'"] _ zoom level _ imageWidth, image heigth is calculated, and anyway the output is cropped to its smallest extent to make page formatting more concise. _ output image filename Output: _ png image of width =< 'width' How it works: First, the stylesheet is serialized to include all external references. Then create_legend_stylesheet() create a new stylesheet to be use directly with osm datasource plugin, avoiding the need to create a postgres database. To provide a render as close as possible to the original stylesheet, any sql query from the <layer> part is translated into a <filter> in the <style> sections. The mapnik osm datasource plugin does not features (yet ?) the osm2pgsql complex handling of polygons. Thus area features (ie rectangle and squares) are affected with a tag [is_area]='yes' and all rules from the style sheet not featuring a PolygonSymbolizer are modified with "and not ([is_area]='yes')" to avoid rendering artifacts. Central points and 'name' should be described with rectanglepoint and rectangletext elements, resp. squarepoint and squaretext. Tools: legend_compact.xml is a legend descriptor file dedicated to create formated html legend with several element in a line. It (should) contains all the elements rendered by the slippy map except turning circles which are not handled by RenderLegendElement.py. RenderLegend.py shows how to render pics of every legend elemnts from legend_compact.xml. RenderLegendFast.py is a faster (2x) version of the above, calling directly functions create_legend_stylesheet() and createOsmElement() to avoid complete parsing of the stylesheet for each legend element. An example of use of legend_compact.xml and pics of legend elements pre-rendered with RenderLegendElement.py can be seen here: http://dev-yves.dyndns.org/legend/page.html.