[OpenLayers-Users] mark a selected area as negative/positive

[Christian.Sell.ext at atis-systems.com]

Hello all,

I have a requirement thath the user be able to select a rectangular area of a map (via box selection) such that thereafter, the selection can be visualized either positively or negatively, meaning "only the selected area" or "everything except the selected area". To visualize the first case, I would like to have the map covered with a semi-opaque color (or some pattern), with the exception of the selected rectangle, where the map should be displayed normally. Vice-versa for the second case.

Can somebody give me a pointer how to implement this? It is of course easy to draw a box with fillOpacity=0.5 (covering case 2), but I am unclear how to cover the other case.

TIA,
Christian

 ////////////////////////////////////////////////////////////////////

ATIS systems GmbH
Sitz: Bad Homburg
Registergericht: Bad Homburg HRB 1514
Geschaeftsfuehrer: Helmut Huschka

________________________________________________________________________________________________

This message is confidential. It may also be privileged or otherwise protected by work product immunity or other legal rules. If you have received this message by mistake please let us know by reply and then delete it from your system; you should not copy it or disclose its contents to anyone. All messages sent to and from ATIS systems GmbH may be monitored to ensure compliance with internal policies and to protect our business. E-Mails are not secure and cannot be guaranteed to be error free as they can be intercepted, amended, lost or destroyed. Anyone who communicates with us by e-mail is taken to accept these risks.





-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/openlayers-users/attachments/20121205/19bc0937/attachment-0001.html>