Hi Mike,

There is a flaw in your advice :) or to be more precise the way you
are suggesting is:

1. create overlay
2. let user click randomly on the map
3. analyse that click server side and return response

If I got your advice right.

The way Google is doing it is as you describe it, they get the image
and than make a call to get the hotspots. From what I can gather they
get the hotspots on mouse move over a region.

This is the call for hotspots:

http://mlt0.google.com/mapslt/ft?lyrs=lmq:0:coffee%7Cs:115968771510351694523%7Ch:2d%7Ccc:US&las=tuvuwttwtwttt&z=12&hl=en&callback=_xdc_._ffun141bq

Here is the source snippet:

_xdc_._ffun141bq && _xdc_._ffun141bq([{id:"tuvuwttwtwttt",base:
[346060800,748922880],zrange:[12,12],layer
:"lmq:0:coffee|s:115968771510351694523|h:2d|cc:US",features:
[{id:"171662889802079419",a:[0,0],bb:[-4
,-4,4,4]},{id:"2213700196724359499",a:[2048,10240],bb:[-4,-4,4,4]},
{id:"9099123815756351988",a:[2048
,10240],bb:[-4,-4,4,4]},{id:"10895832145966586989",a:[6144,-135168],bb:
[-4,-4,4,4]},{id:"6935616885735586915"
,a:[4096,-118784],bb:[-4,-4,4,4]},{id:"6570805103605300637",a:
[131072,-114688],bb:[-4,-4,4,4]},{id:"4923754615869659171"
,a:[6144,-133120],bb:[-4,-4,4,4]}]}])

>From what I'm able to get from this we have JSONp with:

id : probably has something to do with the region that we want the
hotspots
base: ???
zrange: zoom level range (always current zoom , current zoom from my
experience)
layer: reference to query
features: actual data

Feature item:
id: used to get bubble data (example
http://maps.google.com/maps/iw?ftid=10895832145966586989&lyr=lmq%3A0%3Acoffee&callback=_xdc_._rfun1hppo
)
a: no clue what, best guess it is reference to some from some point
bb: bounding box size (icon size)

so once they get the hotspots they can listen to mouse move and change
the cursor once the hot spot is hovered. Also they are able to get the
id and create the JSONp call for the bubble data.

Closet to what is describe here can be found at this page:

http://www.usnaviguide.com/ws-2008-02/demotilecookies.htm

But still for the future it would be nice to know how its officially
done so we don't have to reinvent the wheel. Maybe some day we will be
able to add our overlays to Google maps as first class citizens :)

If anybody has better insight in this data please help.

BTW I'm new around here and I'm not sure if reverse engineering Google
data/js is legal at all.

utvara



On May 12, 7:31 pm, Mike Williams <[email protected]> wrote:
> Wasn't it utvara who wrote:
>
>
>
> >Hi,
>
> >I know I'm repeating the question, but does anybody have any idea how
> >the hot spots are handled?
>
> Yes, but I still advise:
>
> >> If you want that, then add it later after you get the primary
> >> functionality working.
>
> --http://econym.org.uk/gmap
> The Blackpool Community Church Javascript Team
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