Invalid DPI reported with screen spanning several displays
Submitted by Yaroslav
Assigned to Xorg Project Team
Description
Long story short: while using several displays as single screen, xrandr report wrong (very small or very large) DPI, e.g. for it becomes something like 130 DPI for 3 23" LCD displays 1920x1080 set in vertical array.it looks like xrand calculates pixel diagonal for entire screen - sqrt(1920^2 + 3240^2) = 3766 and divides by diagonal in inches of single LCD (got it from EDID?) In some cases DPI is very small - 30-20 DPI and I didn't figured what causes that, but I experienced it while using same display setup with "Nvidia" driver. Result is huge or very small font or spacing between lines in most of application that use font relying on DPI, in first place Qt-based GUI , text editors, etc. Only workaround for that which I found is to set DPI manually equal to native DPI of panel in display section of configuration file (may be there is also xrandr command which can do that?), but I wonder if such behavior is known and acceptable.
Version: 7.7 (2012.06)