On-screen keyboard has no Backspace key

[blueflaivore]

Summary

The built-in on-screen keyboard has no Backspace key, so text can be typed into Flash content but not corrected.

Details

The tags currently defined in app/src/main/res/layout/keyboard.xml are:

1–0, Q–M, CTRL, ALT, SPACE, LEFT, UP, DOWN, RIGHT, plus kb and cm.

key_tag_to_key_descriptor() in src/keycodes.rs accepts exactly the same set, so there is currently no tag that could map to Backspace.

The hardware keyboard path already handles it, though — android_key_event_to_ruffle_key_descriptor() maps Keycode::Del to NamedKey::Backspace. So a Bluetooth keyboard works fine; only the on-screen keyboard is missing the key. (Enter and Shift appear to be absent as well.)

Question before opening a PR

The change looks small: one more match arm in keycodes.rs plus a button in the layout. Before spending time on it, I'd like to check the intended direction, because the README TODO lists:

[ ] Ability to show the built-in virtual keyboard (softinput), for text input

If the system soft keyboard is the planned route for text input, adding keys to the custom overlay may not be what you want, and I'd rather not send a PR that pulls the other way.

Happy to prepare the change if it's welcome — just let me know which approach you'd prefer.

Observed on 0.260720 (F-Droid).

[torokati44]

Even if popping up the system's own soft keyboard is implemented for entry into text fields, the existing handmade keyboard should still be kept, as that's the only way to have individual press/release events for each key, even in an interleaved fashion, as many flash games require it. So adding the missing backspace key is definitely useful, regardless of when/if that's done, as that could also be another key for which some content expects said events! Thank you for considering a PR!