[OSM-dev] Openlayers cyclemap permalinks

Andy Allan gravitystorm at gmail.com
Mon May 19 10:17:00 BST 2008


On Sat, May 17, 2008 at 11:51 PM, Thomas Wood
<grand.edgemaster at gmail.com> wrote:
> On Sat, 2008-05-17 at 21:47 +0100, OJ W wrote:
>> The cycle map seems to have the openlayers permalink bug [1] - is it
>> possible to apply the latest openlayers corrections so that it uses
>> lat/long in permalinks?
>>
>> Can someone from OL also reply to this, saying how to do the correction?
>>
>>
>>
>> [1] http://www.gravitystorm.co.uk/osm/?zoom=13&lat=6781599.86453&lon=-126905.18782&layers=B00
>>
>> 6781599 degrees north is not the usual way of representing positions
>>
>> _______________________________________________
>> dev mailing list
>> dev at openstreetmap.org
>> http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/dev
>
> As noted on IRC, this is not a bug, but a raw expression of the way we
> make our tiles, the numbers represent the distance in meters from the
> origin. I guess they're not strictly lats and lons, but its just OL's
> terms for the permalink.
>
> Attached is a modified copy of the map.js used on gravitystorm.co.uk
> which uses the projection features in OpenLayers 2.6, it sets
> displayProjection to fix the bug, and changes the existing reprojection
> functions to be wrappers around the OL code.
>
> It should just slot in, but is untested. It should also handle the
> existing permalinks semi-intelligently, assuming they're the old format
> if:
> a) The OL permalink control puts the position outside of the map's
> maxExtent (ie: sets centre to 0,0)
> b) lat, lon, zoom params are numbers (checked to be outside the expected
> range for lat lons)

Wow, cheers for this.

As for the other replies - it wasn't something I'd ever thought of
when setting it up originally, but the next version of the map had
this "fixed" (using the new openlayers). What I'd be very interested
in is a little php script which takes the old style URLs and throws a
301 to a different URL with new-style urls after having done some
maths.

Cheers,
Andy




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