[barrkel]

A compositor can only do scrolling if the app is written with a retained mode API. The low-level APIs in Windows are immediate mode, whether GDI or Direct2D.

For most of time, ScrollWindow / ScrollWindowEx was how you scrolled. It doesn't know what to draw in the invalidated region because it's an immediate mode API.

In Direct2D you can use e.g. a translation to get the renderer to draw a bigger bitmap in a different section of the window, but you need to render the bigger bitmap (i.e. assemble your own retained mode). There's no free lunch.

[youdounderstand]

I'm talking about the UWP/XAML/DirectComposition world, which admittedly is not game-related.