KeyCode not sent for modified keys?

[icefoxen]

Basically this is a question about "is this behavior intended?"

Using SDL2, when I press / then SDL sends a Slash keycode. Winit does the same. But if you press shift-/ (aka ?), SDL sends you the Slash keycode and Winit gives you the scancode but None for the keycode. Not sure what the "correct" approach is, so, is this intentional?

[francesca64]

Which platforms?

[icefoxen]

Only looked at Linux+X11. Let me check Windows.

[icefoxen]

Ok, on Windows, it uses SDL2's behavior; shift-/ produces a Slash keycode.

It didn't occur to me that there would be platform-specific differences/bugs. XD Linux is using xorg 1.19.6 on Debian Buster. Unfortunately I can't check Wayland or MacOS.

[francesca64]

Looks like macOS has the same behavior as SDL too. Wayland just uses libxkbcommon, so it probably works too, though I can check with Weston I think.

It didn't occur to me that there would be platform-specific differences/bugs. XD

Much of winit's development history was pretty disjointed (since most people only contribute to one platform) so things like this are still pretty common, despite my best efforts.

[icefoxen]

Well, I'll see if I can submit a PR then. Likely culprits appear to be around https://github.com/tomaka/winit/blob/master/src/platform/linux/x11/mod.rs#L579 or https://github.com/tomaka/winit/blob/master/src/platform/linux/x11/mod.rs#L1031 . keysym_to_element() seems to mostly just do what it should be doing, I need to dig through X docs (start at man xkeyevent?) to figure out the details of what's going on.

[francesca64]

Well XLookupString is objectively terrible, or something like that (very deprecated). Since that's how we get the keysym, and we use the keysym to get the virtual keycode, that's an easy hole for problems.

The XI_Raw* stuff is for DeviceEvent, which use XInput2. If you want to know what that entails, well, I can tell you that too... XKeycodeToKeysym is probably deprecated too.