wayland: Handle axis_value120 scroll events

[ids1024]

This can be tested with the application example, looking at the events shown for mouse wheel movement.

wl_pointer::axis_discrete isn't sent in version 8 or higher of wl_pointer. And sctk doesn't convert the value120 events, so on compositors advertising version 8, only pixel scroll events were being sent.

This sends MouseScrollDelta::LineDelta with a fractional value, without doing any accumulation. Given LineDelta contains f32 values, this presumably is expected?

Though it might be good to change the definition of MouseScrollDelta to include both discrete and pixel values, when the compositor sends both. I'm not familiar with how this works on non-Wayland backends though.

• Tested on all platforms changed
• Added an entry to the changelog module if knowledge of this change could be valuable to users
• Updated documentation to reflect any user-facing changes, including notes of platform-specific behavior
• Created or updated an example program if it would help users understand this functionality

[kchibisov]

This sends MouseScrollDelta::LineDelta with a fractional value, without doing any accumulation. Given LineDelta contains f32 values, this presumably is expected?

I think so. We can address it later on, it's not a big deal to add accumulation if it's actually expected, since from what I can read, it should be ok from the API stand point, since nothing stops from reporting e.g. half a line.