[mapserver-dev] mapcache: background color
daniele at geosar.ch
Tue Jan 8 06:30:16 PST 2013
working with mapcache I had a problem with the request of tiles that are
half-in and half-out the extent.
The outside part of the image has a white background color instead of
transparent as I was expecting (using png).
After looking at the code I found that function
"mapcache_image_copy_resampled_bilinear" in file lib/image.c
using PIXMAN library, do a "pixman_image_composite (PIXMAN_OP_SRC, ..."
call and this sets the
white background color.
Changing it to PIXMAN_OP_ADD solves my problem and I finally get the
Is there a specific reason why the PIXMAN_OP_SRC is used?
I tried with others operations too, like PIXMAN_OP_OVER and others, but
I noticed performance problems.
Which is the best operation to do in this case?
Thanks in advance,
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