mapnik-org/mapnik — Issue #202: map.buffer_size() does not seem to fetch data within buffer zone
Author: artemp
Created: 2011-10-11 07:42:20+00:00
State: open
Labels: Core_Library

I've recently switched the mod_tile code to using map.buffer_size() to fix the issue with labels being cut-off at tile borders. Unfortunately it does not seem to be working properly.

The previous algorithm rendered a map with half a tile extra around the edge of the map and that worked OK.

Looking into feature_style_processor apply_to_layer() I see that it builds the bbox for the datasource query from the map.getCurrentExtent(). This does not seem to make any account for the buffer_size. I think it needs to add the buffer_size to the extent when querying the datasource so that items which may exist in the buffer zone get a chance to be rendered on this tile (e.g. text label for a point just beyond the tile border).