[mapserver-users] Fwd: Re: [MS4W-Users] transparency with php mapscript

Gramenz, Jens Jens.Gramenz at leibniz-liag.de
Mon May 27 06:16:04 PDT 2019


Hi Sven,
I encountered the same problem few weeks ago. The pattern does exist: If the width of the image is not evenly divisible by four, than the layer transparency fails.
I was just about to write a message like yours, but as I managed to reproduce the bug with a small testscript, I stumbled upon an error and then found out that it is already a known thing...

http://osgeo-org.1560.x6.nabble.com/Layer-opacity-not-working-td5292269.html

As Jeff pointed out, if you built it on your own, then you can disable pixman, if you don't actually need it... Cairo support was dependent of pixman I think.
If you are using a compiled package, maybe you can circumvent this issue by using the OPACITY at CLASS level. I know that OPACITY is already deprecated, but it might be useful until we are forced to use COMPOSITE blocks.

LAYER
__OPACITY 50 # doesn't work
__CLASS
____STYLE
______OPACITY 50 # works
____END
__END
END

If the layer objects are disjoint, the result should be the same. If polygons of the same layer overlap their opacities will add up, which or might not be useful behaviour...

I am also interested in alternatives. For example: Is it possible to change pixman, so the bug doesn't occur? Sadly, I didn't manage to compile Mapserver with PHP7 myself yet. If it turns out that nobody needs Pixman/Cairo and MS4W will be compiled without it, it would be fine for me as well.

Best wishes,
Jens

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