Receiver 4.1 – the wrinkle gets smoothed (at least a little)

Posted: March 17, 2014 in Citrix

I haven’t had any time to work on this yet, but I still have the call open with Citrix.  However, my coworker who found the issue also found a way to get the full resolution he was looking for.  He went into the Display Settings and set the slider for “Change the size of all items” down to Smaller.  Obviously, this peaked my interest..  (And for reference, here is a link that discusses these settings http://www.eightforums.com/tutorials/28310-dpi-scaling-size-change-displays-windows-8-1-a.html.)  I immediately started thinking that it might be tinkering with the dots per inch (DPI) settings (http://en.wikipedia.org/wiki/Dpi).   As most long term Citrix admins will know, by default the ICA sessions are going to run at 96 DPI; this has been the standard display setting for years.  However, many of today’s high resolution monitors run at higher DPI settings to keep the fonts etc. from becoming microscopic.

So, on to some testing.  I booted up my Win 8.1 system I’m testing with and connected in.  As before, i got my 1536×864 resolution.  I jumped back to the local machine and checked that “Change the size…” setting, and it was set to the middle of the slider.  So, I logged out of my Citrix session, set the slider to the smallest setting, and logged back into my desktop.  Eureka.. full resolution. I sent an email to my engineer at Citrix with what I had found, and used some numbers that sounded good in my head.  (As it turns out, it was a fantastic guess.. the numbers were exactly correct).  What I found was this —

Normal View 96 DPI Scaled View 120 DPI Ratio (96/120)*100 = 80
1920 1536 80%
1080 864 80%

There’s the resolution I was getting.. So, I jumped in and went through the whole sequence again to test the next level. And came up with similar results.

Normal View 96 DPI Scaled View 144 DPI Ratio (96/144)*100 = 67
1920 1280 80%
1080 720 80%

It came out exactly as I had guessed it would based on 2 seconds of math.  I have since sent these results to Citrix, and it is completely reproducible.

So my working theory is that when the Receiver connects from a high DPI system, it cannot properly negotiate the resolution if the scaling is turned on.  I also believe that Windows 8.1 starts with the scaling enabled, whereas Windows 8.0 does not.  And when 8.0 is upgraded to 8.1, the DPI settings are left alone as a user preference.  It’s a good theory, and all the evidence bears it out.

David F.

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Comments
  1. Glad to help Bill!

    David F.

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