[OSM-dev] Rules file for OSM renderer

[nick at hogweed.org]

As mentioned on the talk list, the OSM renderer at 
nick.dev.openstreetmap.org/index.php has had one or two updates since last 
week. The main thing is that look and feel is now controlled by a rules file. 
An example is at:

http://nick.dev.openstreetmap.org/freemap.xml

It's generally fairly self explanatory. Each rule has a set of conditions (all 
conditions must be fulfilled) followed by a style.

The main things worth elaborating are:

width: represents line width. Is a list of comma-separated values, one for 
each zoom level. 0 means do not draw the line.

dash: the dash pattern, if applicable: first figure, number of pixels 'on', 
second figure, number of pixels 'off'.

z-index: drawing order. Types with a low z-index will be drawn before those 
with a high z-index.

text (for points of interest): font size for labels accompanying points of 
interest. Again, a comma-separated list for different zoom levels. -1 means 
"do not display the point of interest at all"; 0 means "display the point of 
interest, but do not display a label.

I'll probably expand upon this on the wiki.

Nick