One of the annoyances that people have faced with MapGuide Open Source is that the selection colour was hard-coded in one of the C++ rendering functions. There were a few ways of getting around this without recompiling, but they were all a lot of work. RFC 38 included some code changes that made it possible to modify this value on the fly, but it doesn’t look like this capability was taken advantage of by the AJAX viewer that was distributed with MGOS 2.0.x.

If you’re using MapGuide Open Source 2.0 (2.0.2 recommended) and are not happy with the default blue selection colour, you can easily change it on a per-install basis by modifying the mapviewerajax template file. This is located at:

(INSTALLDIR)\WebServerExtensions\www\viewerfiles\ajaxmappane.templ

You will need to find the function called RequestMapImage, which includes a line that looks like this:


url = webAgent +
"?OPERATION=GETDYNAMICMAPOVERLAYIMAGE&FORMAT=PNG&VERSION=1.0.0&SESSION="
+ sessionId + "&MAPNAME=" + encodeComponent(mapName)
+ "&SEQ=" + Math.random();


You will need to modify this to change the VERSION to 2.0.0, and add the BEHAVIOR and SELECTIONCOLOR parameters:


url = webAgent +
"?OPERATION=GETDYNAMICMAPOVERLAYIMAGE&FORMAT=PNG&VERSION=2.0.0&SESSION="
+ sessionId + "&MAPNAME=" + encodeComponent(mapName)
+ "&SEQ=" + Math.random() + "&BEHAVIOR=7&SELECTIONCOLOR=FF5300FF";


Before:

After:

The BEHAVIOR parameter is a bitmask that controls what is rendered, and is described in RFC 38. The SELECTIONCOLOR parameter is a hex string in RGBA format, or its integer equivalent. Note for geeks: the A (opacity) portion of the string is ignored; the server code masks this out of the passed value, and then adds 200 (C8) as the line opacity and 160 (A0) as the fill opacity.

Note, the mapagent call allows you the flexibility to add more complicated behaviour to your viewer, such as changing the selection colour dynamically based on the map name, but I’ll leave that as an exercise for the reader (mostly because I’m lazy and use Fusion anyway and wouldn’t benefit from the work).

-J