three drop downs:
button name / gray help text in input
- Pre-Calculate / auto-calculate and cache the extent for this layer
- Dynamic / for each map draw dynamically fetch the extent (can be slow)
- Custom / Limit the drawing of the layer with a custom 'minx,miny,maxx,maxy' in the projection of the data
With Pre-Calculate
the default. Dynamic
would maintain the current TileMill 0.9.0 behavior, which hurts performance. Custom
would be for advanced users that want to (ab)use this setting to actually limit large data. In the future we could make this option available for all datasources, not just postgis.