scaling - My WPF app is per-monitor dpi-aware out of the box. I was not expecting that?

Question

I am a bit confused about per-monitor dpi-aware in WPF. I thought you need to do some work to make your windows scale properly on different monitors (as described in Developing a Per-Monitor DPI-Aware WPF Application).

But I've just ran my app on pc with two monitors (2560x1440 and 2160x1440) and the dialogue would automatically scale itself when I move it between monitors. That's on the latest fast ring Windows 10. Am I missing something?

Answer 1

What you see is an example of System scaling when one app window moves to a different monitor with a different DPI. That is because WPF apps are by-default System DPI Aware. As a result, if you notice carefully, you'll see WPF visuals/text gets blurred when the target DPI is higher or they look fuzzy when the target DPI is lower. Also, note that monitor resolution does not matter for WPF apps, since WPF is device resolution agnostic (it's measurement unit is Device independent Pixels).

Good news : .NET 4.6.2 preview just got released and it hasPer Monitor DPI Awareness out of the box. Check out the developer guide and samples here :

https://github.com/Microsoft/WPF-Samples/tree/master/PerMonitorDPI