[mapserver-dev] RFC113 Chainable Compositing Filters

[thomas bonfort]

Hi All,

I have finished implementing the chainable compositing filters that
were architectured along with RFC113, and the code has been committed
to the master branch. The aim of the development is essentially to
enable soft shadow and blurring effects, although other usages can
exist or could be added in the future.
To obtain a soft shadow effect that can be seen for example around the
buildings on http://sitn.ne.ch/production/wsgi/mobile/?theme=mobile_default&baselayer_ref=plan_ville&map_x=554942.49763489&map_y=200242.9936142&map_zoom=6&tree_layers=
you can use

LAYER
 NAME "buildings"
 TYPE POLYGON
 COMPOSITE
  #create the shadow/blur effect by translating a blurred version of the layer
  COMPFILTER "grayscale()"
  COMPFILTER "translate(5,5)"
  COMPFILTER "blur(4)"
  OPACITY 50
 END
 COMPOSITE
  #and render the buildings themselves
  OPACITY 100
 END
 CLASS
  STYLE
    COLOR 128 128 128
    OUTLINECOLOR 0 0 0
    WIDTH 1
   END
  END
END

The currently available filters are:
- "blur(integer)"
- "translate(integer,integer)"
- "grayscale()"
- "blacken()"
- "whiten()"

I'll add some documentation and autotests next week.

best regards,
Thomas