[PATCH v2 app/xrandr] Document that --dpi and --fbmm options set DPI of whole X screen

[Giuseppe Bilotta]

On Wed, Nov 1, 2017 at 11:25 AM, Pali Rohár <pali.rohar at gmail.com> wrote:
> Hello, can somebody process this my patch?
>
> There are no objections for a long time and Walter already reviewed it.
>
> On Monday 07 August 2017 18:45:22 walter harms wrote:
>> Sorry, i had the idea you already got my ack.
>>
>> Reviewed-by: Walter Harms wharms at bfs.de
>>
>> Am 07.08.2017 12:56, schrieb Pali Rohár:
>> > walter, any other objections? I fixed problematic parts which you pointed.
>> >
>> > On Monday 24 July 2017 20:34:39 Pali Rohár wrote:
>> >> Explicitly document and make it clear that those options do not change
>> >> DPI of some monitor output. Also state that these options have no useful
>> >> meaning for multi-monitor configuration.

Personally, I disagree with the statement that the core DPI value has
no useful meaning in multi-monitor configuration.

The core DPI (which is what is controlled by these flags) is the
fallback value for Xft.dpi, and I routinely use it (as it's easier to
modify dynamically) when starting legacy applications to have them
scale according to the monitor I'm going to launch them on.

With Qt, by setting it to the DPI of your primary monitor and enabling
automatic screen scale factor computation, you can even get some
decent mixed DPI support from quite a few applications.

In fact, I would argue that it would be useful if all toolkits and
applications that care about mixed-DPI setups on X11 would use a
similar strategy: compute per monitor scale factors as Xft.dpi *
primary.dpi/monitor.dpi (where primary.dpi is the DPI of the RANDR
primary screen and monitor.dpi), and as usual with Xft.dpi falling
back to the core DPI if unspecified.

(Heck, I would even argue that the core DPI should be set to the
primary monitor DPI by default, regardless of whether the system has
one or more than one monitor.)


-- 
Giuseppe "Oblomov" Bilotta