On 13 Mar 2003, Ben Guthro wrote: > I am in the process of writing hardware / software monitor color > calibration software for linux under Qt. In doing so, determining the > monitor hardware that is currently running is quite paramount. The DDC > seems to probe the monitors, then store this EDID data in an atom called > XFree86_DDC_EDID1_RAWDATA > > While this method seems to work great in a single monitor environment, a > Xinerama environment seems to be different. > > Since there seems to be a shared Screen between the Xinerama displays - > is this EDID data still stored somewhere? > > Though the full EDID data would be nice, ultimately, I merely need a way > off accociating specific screen coordinates to a monitor Vendor / Model > / serial number triplet > > Any insight into this matter would be greatly apprecated
Xcms is an existing industry standard color management scheme for X servers. It also uses atoms (such as XDCCC_LINEAR_RGB_MATRICES) to maintain state and make it available to applications/libraries. See "man xcmsdb" for the way one implementation handles these atoms. I haven't looked at the Xcms code for creating these atoms, so I don't know whether it copes with Xinerama. (I do have a program which can be used with xcmsdb to read XFree86_DDC_EDID1_RAWDATA and create the XDCCC_ atoms, but conventional wisdom is that the color data in many monitor EDIDs is worse than using established defaults - and I've seen figures to prove that). Xinerama didn't exist when I wrote the code for the atoms XFree86_DDC_EDID1_RAWDATA and XFree86_DDC_EDID2_RAWDATA, and I've never got around to looking at what to do. As you say, Xinerama presents a single screen, and thus properties on a single root window, but there are multiple sets of EDID data to present. I've heard talk of ways of refering to the separate heads for use in commands which take a display as argument, but I haven't seen anything working. With Xinerama, since a window may be moved between screens at any time (or appear on more than one at the same time) it isn't really appropriate for a client to ask about the monitor it is displayed on, but I can see that it may be sensible for "configuration" type applications to have access to both sets of monitor information at the same time. The X log file contains most of the EDID data (and I have a program which can parse most of it) so that might be the easiest way to get what you need. I haven't tried very hard, but I can't remember ever seeing correct EDID data for two monitors into the XFree86_DDC_EDID1_RAWDATA atoms of a dual head setup, and I would definitely not like to rely on it for a dual-head card. Sorry I can't be very positive. -- Dr. Andrew C. Aitchison Computer Officer, DPMMS, Cambridge [EMAIL PROTECTED] http://www.dpmms.cam.ac.uk/~werdna _______________________________________________ Devel mailing list [EMAIL PROTECTED] http://XFree86.Org/mailman/listinfo/devel
