[OpenLayers-Users] MapTips

[Matthew Atkins]

OpenLayers Users,

 

I am currently replacing an ArcIMS HTML Viewer application with a new
OpenLayers interface which will be a great leap from what they have in
general navigation usability. I think that I won't have much trouble
replacing almost all of the other functionality (Identify, Measure,
Select, etc.) provided by the ArcIMS application but there is one that I
am not sure of the best way to handle in order to port over the same
effect and response... and that is a feature we call MapTips.

 

If you are not familiar with the term "MapTips" then here is a brief
description - in the ArcIMS application only one layer can be
selected/active at a time. We have a button that toggles MapTips on or
off for the selected layer. When it is turned on the user can just mouse
over any feature from that layer on the map and a pop up (DIV) shows
attribute data for the specific item they are hovering over. It's
basically a quick identify on a feature but the information has been
preloaded so it is very quick and easy to use.

 

If you are not familiar with ArcIMS web sites then here is some
information on how they accomplish this - by default, at least for older
(pre 9.2) versions of ArcIMS, only a single image is returned at any
given time to draw the entire map. So, to create MapTips, a spatial
query is done for the current extent and selected layer ... from the
results of this query an image map is created for the current map image
thus making the "hot spots" that will capture the mouse over event a
trigger the showing of the attribute info in the DIV.

 

So, using OpenLayers instead of the generic ArcIMS HTML Viewer poses a
challenge with the tiles/grid of the map images. At least it means that
we can't use exactly the same methodology as before, but maybe I could
take the same idea and make an image map for each tile that comes in
from my WMS service. Or, maybe I could have markers appear on all the
features of the selected layer when MapTips are toggled on so they can
handle the mouse over events. But, how will that be handled dynamically?
When the user navigates outside of the current view and new features
come into view they need to have a marker appear on them. Are the more
alternatives that might be a better way to handle this scenario?

 

I was just curious to see if anyone has attempted something like this
with OpenLayers already or if anyone has thoughts on the best areas of
OpenLayers to utilize or hook into to make this functionality work in a
graceful manner.

 

Thanks in advance for any and all comments,

 

Wally Atkins

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