[mapserver-users] transparent shapes?

[Frank Warmerdam]

Vladimir Guzmán wrote:

> Hi all.
> I want to know if there is a way to draw a layer with transparency in 
> mapserver.
> Something like an alpha channel or something.  Should I define it in the 
> .map file?


Vladimir,

I think I can safely state that this does not exist at this time.  Are you
wanting transparency for layers within the map, or do you want to produce
a PNG file with transparency so that you can see an image under the png
through it?

In theory, it should be possible for MapServer to be jimmied to produce PNG
files where some color entries have transparency, but I am not convinced this
would work with many browsers.

If (as is more likely) you want transparency within the map between different
layers, that would be somewhat harder.  Part of the problem is that map images
are not composed in 24 (or 32) bit color, but rather as eight bit paletted
images.  This makes fancy effects like alpha blending very difficult.

Perhaps after a future upgrade to gd2.x some options like this could be
considered.


Best regards,

-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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