use Qt virtual keyboard for Android QML

[accumulator]

EDIT(ghost43): see #8256

[SomberNight]

kivy has some code for Android:

electrum/electrum/gui/kivy/util.py

Line 26 in 7834f6c

def get_default_language() -> str:

[accumulator]

Thanks. I was aware we can do it through jnius, but importing jnius is a bit slow, so I wanted to check if the PyQt QtAndroidExtras module could be used, and if it's faster :)

Edit: seems that the bindings for QtAndroidExtras are very minimal, currently not worth the effort.

[accumulator]

As the virtual keyboard will probably be a source of contention, as its behaviour and style is a personal preference, we could opt to make its use a configuration setting. Just like the UI language, we would need to show a message that the app needs to be restarted for the setting to take effect.

thoughts? @ecdsa @SomberNight

[ecdsa]

no, it should not be optional. we really do not want users to type their seed in a custom keyboard app.
why do you think it will be source of contention?

[SomberNight]

It's quite non-standard for an app to force-replace the system keyboard with its own. I don't recall seeing it before. So some users are bound to complain.
(EDIT: for example, imagine someone having customised their keyboard app to use a dvorak layout and make Doom sounds on every keypress. They are sure to complain to have to make do without what they are used to.)

However, using it for seed entry is a matter of security. I concur that we should not let the user enter their seed using the system keyboard (as it might be any custom app).

[SomberNight]

This broke running on desktop for me.

 ./run_electrum --testnet -g qml
  1.01 | E | gui.qml.qeapp.QEAppController | unable to bind intent: ModuleNotFoundError("No module named 'android'")
  1.10 | W | gui.qml.qeapp | QQmlApplicationEngine failed to load component
  1.10 | W | gui.qml.qeapp | file:///home/user/wspace/electrum/electrum/gui/qml/components/main.qml:273:5: Type InputPanel unavailable
  1.10 | W | gui.qml.qeapp | qrc:/QtQuick/VirtualKeyboard/content/InputPanel.qml:127:5: Type Keyboard unavailable
  1.10 | W | gui.qml.qeapp | qrc:/QtQuick/VirtualKeyboard/content/components/Keyboard.qml:38:1: module "QtQuick.VirtualKeyboard.Plugins" is not installed

Do I need to install something? qml-module-qtquick-virtualkeyboard from apt (ubuntu) is apparently already installed.

[SomberNight]

Apparently the qtvirtualkeyboard-plugin package is needed.