David Winslow ha scritto:
> Hi all,
>
> For a project I'm working on, I would like to be able to request a
> single PNG image from GeoServer that includes not only rendered map
> features, but also some overlays like a scale bar and a legend graphic.
> I have done some work on generalizing the already-present watermark
> code; in particular:
> * separating out the layout from the rendering logic (so now the
> watermark painter receives just a rectangle within the viewport and
> draws itself into that.)
> * adding a parameter to the paint method so that overlay providers can
> do context-sensitive things (like scale bars and geographically correct
> compasses)
>
> Additionally, I redid the layout code a bit to support offsets and
> multiple overlays in the same image request. (Attached is a demo image
> featuring everyone's favorite cactus monster [1]).
>
> The request is a standard WMS request specifying
> format=png-decorated&format_options=layout:mylayout where layout is a
> named configuration (currently the layout code doesn't actually read the
> configuration; it's just hard-coded for the demo above). I am currently
> thinking the configuration should have a 1:1 relationship with xml files
> in ${GEOSERVER_DATA_DIR}/layouts/; a sample configuration file in the
> format I am currently imagining is also attached. I'd be very
> interested in feedback on the configuration.
>
> So that's what I'm trying to accomplish. Ideally, I'd like to get this
> into the next release, but I don't think I will be able to deal with
> backward compatibility with the current watermark configuration, a
> stable configuration file, the user requirements for promotion, etc. in
> time.
>
> In the meantime, I have three questions:
> 1) May I commit this code as a community module?
Yep, this would allow for a code review
> 2) Where on the wiki should this be documented while this feature is
> still under development?
RnD section I guess
> 3) What's wrong with the configuration file?
The configuration file seems fine to me? (hope this wasn't a quiz
question, I did not validate the document ;-) ).
Yet, some documentation would be nice. "affinity" is about location
compared to borders, right? What about render, what is the difference
between overlay and append?
One thing that's missing compared to watermarks is a level of transparency.
Option wise, what do we allow? a string name and a value param?
How many options can we have?
There is thought one issue related to watermarks. The watermarks
are there to force a logo, a copyright of sorts on any and all
WMS output generated by GeoServer, so they must be handled separately
from a layout that the user can somehow control with the request
parameters.
I guess watermarks could be handled as an extra configuration to
the layout, in memory, before rendering the layout, so that
the watermark is always drawn last, on top of everything else.
Cheers
Andrea
--
Andrea Aime
OpenGeo - http://opengeo.org
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