> On 26 Sep 2019, at 04:48, Thiago Macieira <thiago.macie...@intel.com> wrote: > > On Wednesday, 25 September 2019 05:54:20 PDT Morten Sørvig wrote: >> I see two differences between setting the DPI vs a factor: >> >> - You set one value per screen (DPI) instead of two (DPI & factor) >> >> - Qt can compute the factor, according to policy set by the application (as >> mentioned above) > > Assume no one will ever call that function. What's the outcome?
We use the default policy: RoundPreferFloor in Qt 5, PassThrough in Qt 6 (if/when https://codereview.qt-project.org/c/qt/qtbase/+/273956 lands) > > Also, DPIs are a physical property of the monitor, but they don't account for > my distance to it. Previously, I only needed one parameter to toggle, which > was either 1 or 2. Now, in order to properly configure, I need to find out > what the current DPI is and then update it. Some displays like projectors don’t have well-defined physical DPI though. In some cases like macOS configured for “more/less space” the relationship between frame buffer pixels and display pixels is not 1:1, which makes physical DPI less useful. The DPI we are using in Qt is the logical DPI; it need not correspond to any physical measurement of the monitor. 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. > > 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). > >>> Anyway, what's the correct way to specify now that one of my external >>> monitors is highdpi but the other isn’t? >> >> >> The correct way would be to configure the windowing system. Qt would then >> pick up the configuration via the platform plugin. > > Agreed, but for those of us still on X11, that's not na option. > >> In practice, the environment variables you are currently using may be your >> best option on X11. > > Ok, thanks. This becomes the recommendation for KDE Plasma Shell > configuration > for X11 then: continue using the variables as they are. > >> If possible, I’d like us to move away from relying on setting environment >> variables, and/or switch to specifying per-screen DPI instead of a scale >> factor. > > Sure, but where, on X11? I don’t know. That’s the $1M question. Morten _______________________________________________ Development mailing list Development@qt-project.org https://lists.qt-project.org/listinfo/development