[OpenLayers-Users] Layer.Vector with multiple data sources
Alexandre Dube
adube at mapgears.com
Thu Jan 8 12:42:57 EST 2009
Andreas Hocevar wrote:
> Alexandre Dube wrote:
>
>> Hi devs,
>>
>> I want to discuss about a new feature on Layer.Vector : multiple data
>> sources depending on the zoom level.
>>
>> I already developped something very similar :
>> http://dev4.mapgears.com/bdga/bdgaWFS-T.html At zoom level 0 to 3, you
>> will see vector polygons ( regions ). Each level comes from a different
>> source that has been normalized to improve the rendering speed. So,
>> each zoom level has its own vector layer and they are all hidden from
>> the layer switcher. They are controlled by a dummy layer.
>>
>> At first, I thought this was cool, but now that I think about it, a
>> single type of data, the Quebec regions on my example, should be
>> displayed on a single layer. If I want to interact with my data the way
>> it is now, I need to look at 4 different layers and keep track of a
>> dummy layer also. A single vector layer with the possibility to give it
>> multiple data sources depending on the zoom level would be much better.
>> What do you think ? It could be a nice upgrade.
>>
>>
>
> It should be easy to customize the strategy you are using (I assume
> Fixed or BBOX) to change the url and/or params of the protocol on the
> zoomend event (similar to the moveend event handler in the BBOX
> strategy). This strategy would then have to know the urls/params for
> each zoom level, and you would just interact with one vector layer.
>
> Regards,
> Andreas.
>
>
Exactly. It's a common practice on the web to have data normalized by
scales, so it would be quite useful to have such an upgrade.
So, you would modify both BBOX and Fixed ? Do others have opinions
about it ?
--
Alexandre Dubé
Mapgears
www.mapgears.com
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