[winswitch] neither --dpi switch or dpi setting in xpra.conf allows me to set the DPI to fixed value

[Antoine Martin]

On 04/10/16 03:18, Thomas Esposito via shifter-users wrote:
> I'm not sure if this is related to my issue,
Probably is.

> but I have reason to doubt
> that the shared libraries that I extracted from the rpm files are actually
> being loaded.
This may severely impact your experience: missing picture codecs, wrong
DPI, etc..

> In a prior thread, I mentioned that since I don't have admin privileges, I
> manually extracted the following rpms
> https://www.xpra.org/dists/CentOS/6.6/x86_64/ :
(snip)
BTW, you don't need all of those RPMs installed, only the ones that are
required for installing the main "xpra" package. See:
rpm -qpR xpra*rpm

> Specifically, I created a directory named on a shared disk
> (i.e. <my_xpra_extract_directory>) and extracted the files in each package
> in such a way that this directory was effectively the root directory. For
> example, the *.so files were extracted to
> '<my_xpra_extract_directory>/usr/lib64' directory tree.
> 
> I found all of the directories to which I had extracted *.so files and
> added those directories to LD_LIBRARY_PATH.
> 
> When running certain X applications, I get the following error message,
> although the application appears to run fine:
> 
> ERROR: ld.so: object
> '/projects/avenger_de1/thomase/xpra/usr/lib64/libfakeXinerama.so.1' from
> LD_PRELOAD cannot be preloaded: ignored.
See:
http://xpra.org/trac/wiki/FakeXinerama
Things should work reasonably well without it.

> Also, despite my LD_LIBRARY_PATH setting, my Xorg.:100.log file (I'm using
> display :100) reports that it is loading the standard
> /usr/lib64/xorg/modules/drivers/dummy_drv.so, rather than the patched
> driver in
> <my_xpra_extract_directory>/usr/lib64/xorg/modules/drivers/dummy_drv.so..
This will be the source of your DPI problems: you won't be using a
patched dummy driver.

> How can I be sure that any of the libraries that I have downloaded are
> actually being loaded?
That depends on how the application loads its shared objects.
In the case of Xorg, this is probably a hard-coded path you can do
nothing about. (and you probably won't be able to LD_PRELOAD it either)

> On Mon, Oct 3, 2016 at 3:07 PM, Thomas Esposito <thomase00 at yahoo.com> wrote:
> 
>> The fonts rendered by Xorg are very small, and I suspect the reason is
>> because the DPI is being set to an unreasonably low value (i.e. 42x28 now,
>> but varies depending on the monitor setup). Rather than deal with the
>> patched dummy driver, I'm assuming that I should be able to simply fix the
>> X DPI to a reasonable value (i.e. 96x96), since that is what I'm accustomed
>> to anyway, being a Windows user primarily. I know there are quasi-religious
>> arguments about a fixed DPI of 96, particularly with all the high-res
>> monitors available now, but I'd rather not get into that.
The issue you're hitting is that the applications you use do not honour
any of your DPI settings but they try to calculate their own "hardware
DPI" based on the monitor dimensions and screen resolution.
This never works well, which is why we have use a patched dummy driver
to simulate the "correct" values.

If you want to fix this without using the patched dummy driver, your
only option is to edit your etc/xpra/xorg.conf and change the
DisplaySize of the monitor to get the desired DPI value:
https://wiki.archlinux.org/index.php/xorg#Display_size_and_DPI
This will not adapt when you connect clients with different resolutions.

You may also want to try to switch to Xvfb instead of Xdummy by changing
the "xvfb=" line in your xpra config file.

>> Anyway, I've attempted to fix the Xorg DPI by using the '--dpi=96' switch
>> on the xpra command line AND by uncommenting the 'dpi = 96' line from the
>> default xpra.conf file included with the install (which I have copied to
>> ~/.xpra/xpra.conf). In both cases, this does not seem to have any effect,
>> and my fonts and DPI remain unreasonably small.
>>
>> What am I missing?
>>
>> Also interesting, although most likely unrelated,
It is related and very relevant, but sadly it is also ignored by many
applications.

>>is the output I get when
>> running 'xrdb -q':
>>
>> gnome.Xft/DPI: 98304
>> Xft.hinting: 1
>> Xft.antialias: 1
>> Xft.dpi: 96
>> Xft.rgba: none
>> Xcursor.size: 21
>> Xft/DPI: 98304
>> Xft.hintstyle: hintmedium
>>
>> I know the DPI here is for client-side/fontconfig fonts and is unrelated
>> to Xorg-rendered fonts, but I find the value of 98304 to be strange here.
That's the DPI value multiplied by 1024, see:
https://wiki.debian.org/MonitorDPI

Cheers
Antoine


>>
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