[mapserver-dev] RFC49: mapfile simplifications and symbology enhancements

[thomas bonfort]

> I don't have any more comments on the proposed changes. I don't see strong
> benefits for all of them, but if others do them I'm fine with what is
> proposed.

As I said, some of the modifications don't add much functionality, but
reduce mapfile size and maintainance. I agree that the benefits aren't
widespread, but for road layers rendering there is imho a great
advantage.

I'll take the example of a single class of road types, eg. primary
roads, where you want them to be rendered as a uniform-colored line
for far off zooms, and an outlined color for closer ones (with the
name of the roads that show up when you get a bit closer)

* with the current mapfile keywords, your layer would look something like:

class    #for far off views, just a uniform line
  minscaledenom 200000
  style
    color grey
    width 1
  end
end

class #for closer views when an outline appears
 minscaledenom 100000
 maxscaledenom 200000
 style
  width 3
  color grey  #the outline color
 end
 style
   width 1
   color white
 end
end

class #closer view, a bit wider
 minscaledenom 50000
 maxscaledenom 100000
 style
  width 4
  color grey
 end
 style
  width 2
  color white
 end
end

class #closer view, now labels appear
 minscaledenom 25000
 maxscaledenom 50000
 style
  width 5
  color grey
 end
 style
  width 3
  color white
 end
 label
   [snip label definition]
 end
end

[snip repeating this pattern for each scale you want to serve your map
in, each time widening the line widths and repeating the label
definition]

repeat this process for each road class (motorways, trunk roads,
secondary roads, etc...)



* with the proposed changes, the equivalent symbology can be obtained with

sizeunits meters
class
  style
    maxscaledenom 200000
    width 15 #in ground meters
    maxwidth 15 #in pixels, largest width for close up views
    minwidth 1 #in pixels
    color white
    outlinecolor grey
    outlinewidth 1
 end
 style #for roads from far off zoom
   minscaledenom 100000
   color grey
   minwidth 1
   maxwidth 1
 end
 label
   maxscaledenom 50000
   [snip label definition]
 end
end



from a mapfile maintainance point of view, I know which one I prefer :)