[OSM-dev] NOT-saving empty Mapnik tiles
marqqs at gmx.eu
marqqs at gmx.eu
Fri Aug 12 18:18:18 BST 2011
Hi,
I'm trying not to save empty tiles. Until now my approach is very simple but silly too:
The tile is rendered by Mapnik, then stored in a file.
After this, I look at the file's length and delete this file if the length does not exceed 116 bytes.
This is a lot of IO effort. Therefore I would like to determine if a tile is empty BEFORE it is going to be saved. This should be not too complicated in python... at least for someone who understands python. :-)
This is the code snippet:
im = mapnik.Image(render_size, render_size)
mapnik.render(mm, im)
im.save(tile_name, 'png256')
Is there a function like im.is_empty() ?
Markus
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