[OpenLayers-Dev] Topology proposal

[Eric Lemoine]

On Saturday, June 6, 2009, Björn Harrtell <bjorn.harrtell at gmail.com> wrote:
> Not yet, but I was informed by Tim Schaub about the registerPriority
> method on the Event class

for some reason I dont know this method is marked "3.0 remove" IIRC.

>  I suspect that snapping needs the priority
> though, but that's a bit of a guess right now.
>
> I made an effort towards the Control-implementation in sandbox which
> I'm reasonably happy with and the code now tries to follow the coding
> standards of OL, so I guess the only thing missing now from the
> implementation is testcases. That might take a while for me so I'll
> probably create an initial patch for review and discussion against
> post 2.8 trunk when 2.8 is released.

This is great work Björn!

I haven't looked at your code, so I'd just have one unimportant
comment: do you envision other stuff than Rule under the
OpenLayers.Topology namespace? If not I'd rather go with
OpenLayers.TopologyRule to keep namespace depth minimal. What do you
think?



>
> /Björn
>
> On Fri, Jun 5, 2009 at 17:20, Evan James Bowling<evan.bowling at gmail.com> wrote:
>> I think it makes perfect sense to separate the Topology component into its
>> own Control. Were you able to alter the priority of the Snapping vs.
>> Topology controls?
>>
>> -Evan
>>
>> 2009/6/4 Björn Harrtell <bjorn.harrtell at gmail.com>
>>>
>>> I've rewritten the implementation so that topology isn't calculated on
>>> the fly, which I think might solve the problem discussed below and
>>> also improves performance.
>>>
>>> In doing this I got to think about the initial proposal. A redesign
>>> that popped up in my head is to remove the idea that rules are applied
>>> to a Vector layer and instead add a new Control called Topology that
>>> controls the enforcement and renderIntent-stuff for the supplied layer
>>> (or layer)
>>>
>>> The basic idea with the above is to be able to leave the Vector Layer
>>> completely unmodified (it's large as it is :) and also put all user
>>> configurable interaction with the functionality in the control instead
>>> of manipulating the rule. Any opinions?
>>>
>>> /Björn
>>>
>>> 2009/6/4 Björn Harrtell <bjorn.harrtell at gmail.com>:
>>> > The issue you describe is probably caused by conflicts between
>>> > snapping and topology enforcement, more specifically both snapping and
>>> > topology enforcement listen on vertexmodified-events and the order of
>>> > this combined logic is significant. I haven't investigated if I can
>>> > control priority of my event listener, but if that's possible I think
>>> > it would solve the problems.
>>> >
>>> > On another note, the sandbox and example is now updated with an
>>> > initial implementation of the renderIntent-idea which means that at
>>> > each completed feature modification the state of topology will be
>>> > calculated and polygon that does not satisfy the rule will be set into
>>> > the renderIntent state "error" and will be colored in red.
>>> >
>>> > /Björn
>>> >
>>> > On Wed, Jun 3, 2009 at 00:21, Roald de Wit <roald.dewit at lisasoft.com>
>>> > wrote:
>>> >> Hi Björn,
>>> >>
>>> >> Great initiative! Topology preserving editing functionality would be a
>>> >> very
>>> >> valuably contribution to OL (IMHO).
>>> >> I did notice that when you edit one feature, then uncheck 'enforce
>>> >> topology', edit a bit more (by moving vertices) and then check 'enforce
>>> >> topology' again, the enforcing does not work anymore when you move more
>>> >> than
>>> >> the snapping threshold. I know this is work in progress, so you might
>>> >> be
>>> >> aware of it already.
>>> >>
>>> >> I'm sure that more than 1 person (2 now, including me) will be
>>> >> interested in
>>> >> your work!
>>> >>
>>> >> Regards, Roald
>>> >>
>>> >>
>>> >> Björn Harrtell wrote:
>>> >>>
>>> >>> Since I got at least one (and hopefully more :) interested person(s)
>>> >>> in the details I'm posting this information about my initial
>>> >>> implementation of the below proposal using using events in this
>>> >>> sandbox:
>>> >>>
>>> >>> http://dev.openlayers.org/sandbox/bjornharrtell/eventbasedtopology
>>> >>>
>>> >>> Check out the example at
>>> >>>
>>> >>>
>>> >>> http://dev.openlayers.org/sandbox/bjornharrtell/eventbasedtopology/examples/topology.html
>>> >>> to see the implementation in effect.
>>> >>>
>>> >>> The only change from the initial proposal is t

-- 
Eric Lemoine

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