There are some catalog/factory create methods, but the only place I can find LegendInfo really being used is in LayerInfo. The GetCapabilities actually uses the LayerInfo.getLegend() for the defaultStyle. But I couldn’t find anywhere that sets it, so it always falls through as null anyway. The existing LegendInfo class looks like what we need. It has onlineResource, format, width, and height properties; all stuff for the GetCapabilities LegendURL. It kind of looks like someone started down this path, but didn’t go all the way.
The XStreamPersister was the right spot. I added two lines of code and got it working (needed to set an alias and define a default implementation).
Right now I’m working on adding it to the Style web UI.
If you’re curious I’m committing it to my GitHub account:
https://github.com/geocent-yancy/geoserver/commit/6362b5bd8f0625907a0e4c6443aac4a74286231b
I appreciate all your help.
Thanks,
Yancy Matherne
Software Developer
Geocent, LLC
111 Veterans Blvd., Suite 1600
Metairie, LA 70005
O: (504) 831-1900
E: yancy.matherne@anonymised.com
http://www.geocent.com
From: David Winslow [dwinslow@anonymised.com]
Sent: Wednesday, October 03, 2012 8:03 AM
To: Yancy Matherne
Cc: Geoserver-devel
Subject: Re: [Geoserver-devel] GetLegendGraphic Enhancements
Hm, I didn’t realize we already had a LegendInfo. Is it used elsewhere? We might be writing ourselves into a corner if we start reusing the same class for unrelated tasks.
The serialization is accomplished using XStream: http://xstream.codehaus.org/ They have a two-minute tutorial that covers the basics, I’d recommend going through it.
The error message you’re getting says:
Caused by: java.lang.InstantiationError: org.geoserver.catalog.LegendInfo
at sun.reflect.GeneratedSerializationConstructorAccessor4.newInstance(Unknown Source)
That is, org.geoserver.catalog.LegendInfo doesn’t have a default constructor (in fact it has no constructors at all - it’s an interface and so inherently abstract.) So the problem seems to be that XStream is configured to serialize legends without any information about which implementation class to use when deserializing. I believe org.geoserver.config.util.XStreamPersister will need to be modified to account for this, but even if it’s not that’s probably a good place to start digging around.
–
David Winslow
OpenGeo - http://opengeo.org/
On Tue, Oct 2, 2012 at 7:24 PM, Yancy Matherne <Yancy.Matherne@anonymised.com> wrote:
David,
Thank you for your quick reply. I agree with your comments, but have run into a snag.
There already exists LegendInfo and LegendInfoImpl classes, so I figured I would just use those. I added the LegendInfo as a property to the StyleInfo and modified my test style.xml file.
StyleInfoImpl--570ae188:124761b8d78:-7fe2
raster
raster.sld
LegendInfoImpl--570ae188:124761b8d78:-7fe1
50
75
image/png
[http://www.google.com/images/srpr/logo3w.png](http://www.google.com/images/srpr/logo3w.png)
Unfortunately, it is unable to construct the LegendInfo object when it is loading the catalog.
Excerpt from log [see attached tomcat.log]:
…
Caused by: java.lang.InstantiationError: org.geoserver.catalog.LegendInfo
at sun.reflect.GeneratedSerializationConstructorAccessor4.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
at com.thoughtworks.xstream.converters.reflection.Sun14ReflectionProvider.newInstance(Sun14ReflectionProvider.java:74)
…
At this point, I’m not really sure how the XML parsing works, so I’m not sure what the error means. I tried adding constructors with different arguments to the LegendInfoImpl, but I get the same error. Do you have any ideas?
I was able to add the LegendInfo properties directly to the StyleInfo and just create the LegendInfo object on the fly when StyleInfo.getLegend() is called. Of course this isn’t the way to do it, but I was at least able to prove that the GetCapabilities will work as expected.
Thanks,
Yancy Matherne
Software Developer
Geocent, LLC
111 Veterans Blvd., Suite 1600
Metairie, LA 70005
O: (504) 831-1900
E: yancy.matherne@anonymised.com
http://www.geocent.com
From: David Winslow [dwinslow@anonymised.com]
Sent: Tuesday, October 02, 2012 8:40 AM
To: Yancy Matherne
Cc: Geoserver-devel
Subject: Re: [Geoserver-devel] GetLegendGraphic Enhancements
LegendInfo could be embedded in the StyleInfo, and in fact this would happen automatically if you simply make a LegendInfo class and add one as a property of StyleInfo objects. Justin might disagree but I don’t see any potential drawbacks with this approach (unless it’s useful to share legends between styles - but it shouldn’t be, right?)
As for having ShapePainter paint external legends, I think that I would use a separate method rather than trying to wrap Legends as Styles somehow.
–
David Winslow
OpenGeo - http://opengeo.org/
On Mon, Oct 1, 2012 at 7:10 PM, Yancy Matherne <Yancy.Matherne@anonymised.com> wrote:
Hi all,
We have a few weather observation layers that include many attributes, and we use several TextSymbolizers with custom fonts, rotations, anchor points, etc. to generate a complex icon that graphically represents several attributes’ values at the same time [see attached GetMap]. Unfortunately, the GetLegendGraphic service does not generate a useful legend out of the box for these styles [see attached GetLegendGraphic]. The icons for these layers are so complex that a legend like [http://visual.merriam-webster.com/images/earth/meteorology/station-model.jpg] would be more useful than a vertical listing of the rules.
We are looking to patch GeoServer to do two things:
- Point the LegendURL in the GetCapabilities to an ExternalGraphic.
- Implement the LegendGraphic for Rules in SLD.
I have already started looking into each patch, and I think I have a general approach to each.
-
Capabilities_1_3_0_Transformer.handleLegendURL() already takes a LegendInfo parameter, but Capabilities_1_3_0_Transformer.handleStyles() always passes in null. I was thinking we could add a LegendInfo to StyleInfo to persist the ExternalGraphic information. But I’m not sure on the details of this. Would I be able to put the LegendInfo directly into the StyleInfo XML file or would there need to a separate file with references between them?
-
The LegendGraphic element in Rules is part of the SLD spec, but it does not appear (to me) to be implemented in GeoServer. While using the debugger, in BufferedImageLegendGraphicBuilder.buildLegendGraphic(), a LegendGraphic that is included in your SLD is accessible by calling applicableRules[i].getLegend(). But that never happens in the actual code so it never gets used. I was looking to just paint the GraphicLegend there, but the shapePainter.paint() method that is used there takes a Style2D object and I haven’t been able to figure out how to convert a GraphicLegend to a Style2D object or perhaps use a different paint method?
I think these would be useful additions for the whole community and I appreciate any feedback or recommendations on this. Part of the tasking is to commit this back to GeoServer source.
Thanks,
Yancy Matherne
Software Developer
Geocent, LLC
111 Veterans Blvd., Suite 1600
Metairie, LA 70005
O: (504) 831-1900
E: yancy.matherne@anonymised.com
http://www.geocent.com
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