Re: [udig-devel] Wiki page created for new map, map layer and rendering

[Jesse Eichar <jeichar@xxxxxxxxxxxxxxx>]

Nice job on the wiki page.

There were a few questions you had that I will try to clarify:

1. In udig the map is more than just a representation of a map.  It is
also the central location for plugin collaboration, hence the
blackboard.  It also contains many convenience methods for developers.
The starting place for the udig map model is the OGC context document
and was, during design, a superset of the WMS context document (That was
all we had available to use at the time).  
2. Layers can have more than 1 resource and there is a preferred one.
This is because a Web Map Service and a Web Feature Service could all
refer to the same data.  One scenario exists where we would like the WMS
to create maps for us but the WFS can be used to edit the features
automatically.  
3. I'd say the most important features of the UDIG model are if you
would like to take from udig the important parts are certainly the Map,
Layers, ViewportModel, Renderer and maybe the RenderExecutor (This
allows multiple threads to render layers and also allows for
incrementally updating the image).
4. The RenderManager has a component that matches Renderers to layers
which is also important in a system where there are multiple renderers.
This is mostly likely an implementation detail.
5.  Both ReferencedEnvelopes and Envelopes are used because
ReferencedEnvelopes were introduced part way through the developement
and we haven't yet put them through the entire system.  GEOAPI has a
Envelope object as well but it is unwieldly so we didn't use that.
6.  I don't think the blackboard needs to be part of the main interface
but it is really useful for collaboration between plugins and it sees a
lot of use, though not by us (udig developers) but rather plugin
developers.  If it is not part of the main interfaces then we can add it
to out extended interfaces.
7. Each layer does have a CRS that you can explicitly set.  If it is not
explicitly set then it is the CRS defined by the IGeoResource.getInfo()
object.  Typically if the layer is a feature layer then the CRS defined
in the feature type is the layer's CRS.
8. I agree completely with being able to group layers.  I believe
GEOAPI's layer has that concept.


Comments on proposal(I'm running out of time so I have to hurry now):

1. +1 for maps with have events.  A renderer will be need to be notified
if the style changes or if the something happens to the layer's resource
object.
2. I like # 3 for map/layer interfaces. Is a layer group also a layer?


Jesse


On Tue, 2005-08-09 at 18:47 +0200, Matthias Basler wrote:
> Hi developers,
> 
> I have added a new wiki page to the RnD section, describing my thoughts about
> the future map, map layer and rendering architecture within GeoTools:
> 
> http://docs.codehaus.org/display/GEOTOOLS/Map%2C+Layer%2C+Data+and+Rendering+Architecture
> 
> The text is quite lenghty, but you can print it out and read it while being
> stuck in a traffic jam or so. ;-)
> It covers
> - what's there (as far as I understand it - those that developed the classes may
> want to correct errors of mine and add their reasons why they did things the way
> the did them.)
> - where we want to go
> - lots of questions to decide on, our options and my opinion
> - more technical design aspects and some ideas of mine to this
> 
> I have already included some of your opinions/ideas from former emails and would
> like to advance now towards more specific technical suggestions and decisions.
> 
> Since this topic will likely affect many people, I encourage you all to have a
> look and comment on it (either directly in/on the wiki or give me feedback via
> email). This document is in progress, so certain aspects are missing. If you
> find an issue that also needs discussion, add it or tell me.
> 
> I'm looking forward to your ideas and opinions on the questions picked up there.
> 
> Matthias Basler
> c9bama@xxxxxxxxxxx
> 
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