[Development] Qt 5.13 & 5.14 add device-independent pixels to device-dependent

[Thiago Macieira]

On Thursday, 30 January 2020 06:34:02 PST Morten Sørvig wrote:
> macOS works this way, Windows doesn’t. I think the linux desktop
> environments could work this way when using Wayland, but I’m not sure what
> actually do. (The test is; does a 2x screen show up as a very large screen,
> or not)
> 
> If this holds then solving the problem completely is out-of-scope for Qt,
> and we can settle on choosing the least-worst workaround.

I think on Wayland, since the scaling is performed by the compositor, another 
option becomes available, which is to completely change the geometry.

Instead of:

 +---+---+
 | A | B |
 +---+---+
 | C |
 +---+
 
It will look like

 +---+---+
 | A | B |
 +---+---+
 |       |
 |   C   |
 +-------+

The important difference is how the mouse moves across the screen and how 
windows overlapping screens are displayed.

Solving this problem is outside Qt's scope. But the case of linear arrangement 
of screens can be solved. The only questions are whether it's necessary to 
solve it to get the currently-broken applications fixed and if it is, how to 
detect the cases where we can and when to give up.
-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel System Software Products