mouse-over "map tips"

[imap at chesapeake.net]

This "mouse-over" thing was something I spoke with Steve about just
the other day...  

If the data required for the "mouse-over" were derived from a 
Shapefile/DBF or a database, and the polygonal/line/point data 
were stored in the map coordinates, the map engine would have 
to *return* the data required to construct the client-side imagemap.  
Perhaps there could be an argument that could be passed to mapserv to
generate this type of output which can be passed to the front-end java
or CGI.  This task is best handled by mapserv because the front-end needs
the x/y values which would be difficult to derive externally.

For the java front-end
----------------------

The thought for the java version of mapimage.class (or whatever you
might call your java front-end) is to handle the appropriate modal
functions of: ZOOM-IN, ZOOM-OUT, RECENTER, QUERY and the various Mouse 
events in conjunction with the state of a radio button or checkboxes and 
ALSO have that same applet handle the MOUSEOVER of the output of the
client-side imagemap output.  I will need to look at the java book
to see what is available to handle this.  Maybe someone has already
done this??

For the CGI front-end
---------------------

I am not completely sure about this... but can you use a <INPUT TYPE=IMAGE
...>
tag in conjunction with a client-side imagemap?  I think the answer is no, and
someone set me straight if I am wrong about that.   But anyway, you would want
to be able to handle the navigational modes ZOOM-IN, ZOOM-OUT, RECENTER, QUERY
and at the same time...  handle a client-side imagemap to do the mouseover
link.  I am at a loss as to how you do this with a CGI only setup.  If there
are any ideas, I'd like to hear about it.


IMHO, This is a feature that very much needed and mapserv should be enhanced
to
perform this task in the form of a "client-side imagemap" at a minimum. 
Perhaps
solving the client aspect is out of scope.

There are 3 pieces of mapserv output I would like to see.  (1) a map image 
(2)
a client side imagemap if specified  (3) label cache information  

Somehow we WILL get the client-side imagemap part work on the front-end.   
The label cache would be invaluable for post-processing the images, so that
you could programmatically enforce the collision avoidance of the mapserv
execution for subsequent image manipulation.  Follow me?  If it is possible
to get that information in some machine readable format, that would be
wonderful!

Regards,

Chris Stuber (mapsurfer)
Silicon Mapping Solutions, Inc.


> Brent Fraser wrote:
> 
> Steve,  (and all)
> 
>   I ran across http://www.imapper.com/ and saw that they were showing a
> GIF with "map tips" when the mouse passes over road features.
> 
> Looking at the HTML source, I see that they are using client-side image maps
> with
> "area" tags with polygons and mouse-over text (in the "alt" portion of the
> tag?):
> 
> <area alt="Calle Burgos" title="Calle Burgos"
> href="imsql.asp?Layer=Eje_de_vía&Label=Calle_Burgos" shape="poly"
> coords="-41,74,2,77,46,88,46,92,2,81,-41,78">
> Might be an interesting enhancement to MapServer (version 4.0?)
> Of course since most of us are using Steve's spiffy Java mapimage.class to
> interact with the image, it might not be that useful.
> 
> Brent Fraser
> GeoAnalytic Inc.
> 1150 , 633 - 6th Avenue SW Calgary, AB T2P 2Y5
> Tel:  (403)213-2700 Fax:  (403)213-2707
> bfraser at geoanalytic.com
> www.geoanalytic.com