[Geoserver-devel] Small new feature for GetFeatureInfo: rule match count

GeoServer GeoServer Developer
1

+1

-Jukka Rahkonen-

Ben Caradoc-Davies wrote:
Re: [Geoserver-devel] Small new feature for GetFeatureInfo: rule match count

+1 for the plan, option name of countMatched, and StreamingRenderer for
consistency with what the user sees.

Kind regards,
Ben.

On 26/04/17 21:50, Andrea Aime wrote:

Looks like nobody is particularly concerned, so moving on with current plan

Cheers
Andrea

On Mon, Apr 24, 2017 at 2:59 PM, Andrea Aime <andrea.aime@...1268...>
wrote:

Hi,
I'm writing this mail to propose (on behalf of a sponsor) a small new
feature for GetFeatureInfo,
that is, the ability to report the number of matched features in the
requested area as part
of the legend.
It is not the more commonly requested "show only the entries with at least
one item in the map",
but it lowers its implementation bar significantly, making it more likely
to get sponsored in the future.

The request would look like:

http://host/geoserver/wms?REQUEST=GetLegendGraphic&
VERSION=1.0.0&FORMAT=image/png&WIDTH=20&HEIGHT=20*&LAYER=topp:states* //
std legend graphics so far
*&SRS=EPSG%3A4326&SRCWIDTH=768&SRCHEIGHT=330&BBOX=-97.7783203125%2C37.078857421875%2C-89.3408203125%2C40.704345703125
// *identify area of interest
*&LEGEND_OPTIONS=countMatched:true // activate the counting mode*

In order:

   - A standard GetLegendGraphics request, but with a layer parameter
   (normally optional, but mandatory in this case)
   - The part of a GetMap that identifies the current area, using the
   same syntax as GetMap, minus the "src" prefix for width and height, as they
   would otherwise conflict with the legend icon size
   - A legend option to enable it (the implementation of the "return only
   the rules show in the map" would differ only in this bit)

The output would be something like this, with the count within
parenthesis: (graphics as text for the sake of expediency):

[greenSquare] Parks and green spaces (10)
[blueSquare] Water (3)
[graySquare] Urban (150)

Implementation wise, I'm still a bit torn between a CountVisitor call and
a StreamingRenderer pass, but I believe
I'll do the second. Rationale: the logic of a count would need to consider
symbols sizes and whether the output
actually contributes to the visible map, and with a thematic map would end
up having to issue multiple queries,
and would end up returning a count that does not always exactly match the
map on screen.
A StreamingRenderer call against a fake Graphics2D would do a single pass
instead (faster than the equivalent
GetMap for sure) and would end up counting what the user actually sees
instead (it would be in line with
the current GetFeatureInfo implementation, doing the same).

Feedback welcomed. If you think something *needs* to be changed I would
appreciate if you could mark
such comments clearly (I often get confused by comments that is not meant
to ask for a change, but could be
interpreted as such).

Cheers
Andrea

--

GeoServer Professional Services from the experts! Visit
http://goo.gl/it488V for more information.

Ing. Andrea Aime
@geowolf
Technical Lead

GeoSolutions S.A.S.
Via di Montramito 3/A
55054 Massarosa (LU)
phone: +39 0584 962313 <+39%200584%20962313>
fax: +39 0584 1660272 <+39%200584%20166%200272>
mob: +39 339 8844549 <+39%20339%20884%204549>

http://www.geo-solutions.it
http://twitter.com/geosolutions_it

*AVVERTENZE AI SENSI DEL D.Lgs. 196/2003*

Le informazioni contenute in questo messaggio di posta elettronica e/o
nel/i file/s allegato/i sono da considerarsi strettamente riservate. Il
loro utilizzo è consentito esclusivamente al destinatario del messaggio,
per le finalità indicate nel messaggio stesso. Qualora riceviate questo
messaggio senza esserne il destinatario, Vi preghiamo cortesemente di
darcene notizia via e-mail e di procedere alla distruzione del messaggio
stesso, cancellandolo dal Vostro sistema. Conservare il messaggio stesso,
divulgarlo anche in parte, distribuirlo ad altri soggetti, copiarlo, od
utilizzarlo per finalità diverse, costituisce comportamento contrario ai
principi dettati dal D.Lgs. 196/2003.

The information in this message and/or attachments, is intended solely for
the attention and use of the named addressee(s) and may be confidential or
proprietary in nature or covered by the provisions of privacy act
(Legislative Decree June, 30 2003, no.196 - Italy's New Data Protection
Code).Any use not in accord with its purpose, any disclosure, reproduction,
copying, distribution, or either dissemination, either whole or partial, is
strictly forbidden except previous formal approval of the named
addressee(s). If you are not the intended recipient, please contact
immediately the sender by telephone, fax or e-mail and delete the
information in this message that has been received in error. The sender
does not give any warranty or accept liability as the content, accuracy or
completeness of sent messages and accepts no responsibility for changes
made after they were sent or for other risks which arise as a result of
e-mail transmission, viruses, etc.

-------------------------------------------------------

------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot

_______________________________________________
Geoserver-devel mailing list
Geoserver-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/geoserver-devel

--
Ben Caradoc-Davies <ben@...4191...>
Director
Transient Software Limited <http://transient.nz/&gt;
New Zealand

------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
_______________________________________________
Geoserver-devel mailing list
Geoserver-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/geoserver-devel