[Development] Updated high-DPI support for Qt 5.14

Thiago Macieira thiago.macieira at intel.com
Fri Sep 27 17:04:36 CEST 2019

On Friday, 27 September 2019 03:56:44 PDT Morten Sørvig wrote:
> Configuring Windows is a good example here: you set the slider to one of
> 100% - 125% - 150% - 175% - 200% depending on monitor pixel density and
> viewing distance. There’s then a single value to configure.

Well, that's a good example: setting a factor, not the absolute value.

> > Moreover, I can have two different monitors connected to the same output
> > (at different times, of course). Since they have different DPI, the
> > multiplicative factor allows me to set it once for both, but if I set a
> > DPI setting, it'll likely be wrong for at least one of them.
> Yes, we need per-monitor settings (DPI or scale).

The problem on that one is that you're forcing me to keep a value per each 
individual monitor I connect to regularly. With the laptop's display panel, 
that's 4 or 5. Since they are different actual monitors, each has their own 
DPI value, which is obtained by Qt. And some monitors report wildly incorrect 
DPI values, like a 27" monitor saying it's 160x90mm in size. So what's the 
policy for a brand new monitor we connect to (say, a projector in a conference 
room)? Does it: 
 a) keep the physical one from the monitor? 
 b) use 96x96? 
 c) use one of the other monitor's settings? 
(hint: a, b and c are wrong)

Right now, I need exactly two values: the display panel's multiplicative 
factor of 2 and the external output's multiplicative factor of 2.

Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel System Software Products

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