SDL_system/wiiu: add preprocessor define for swkbd API version

[mrpapersonic]

Description

This adds a preprocessor define that describes the swkbd API. The rationale being that there are programs that desire only USB keyboard support, but also wish to retain source-level compatibility with pre-swkbd WiiU SDL versions. For example, Schism Tracker completely breaks when a software keyboard is pulled up.

[GaryOderNichts]

There is no stable API when building SDL from source from the Wii U branches.

The current plan is to release the swkbd feature together with SDL2 2.32 to the pacman repos. To check if swkbd support is present #if SDL_VERSION_ATLEAST(2, 32, 0) can then be used.

For example, Schism Tracker completely breaks when a software keyboard is pulled up.

This shouldn't happen. Do have any further details about this?

[mrpapersonic]

For example, Schism Tracker completely breaks when a software keyboard is pulled up.

This shouldn't happen. Do have any further details about this?

I should've worded that better: Schism's input system is incompatible with software keyboards (in particular the greedy ones that take over the entire screen), hence why we don't want them. It could be possible to circumvent by turning on/off text input depending on whether the current widget accepts text, but we do not do that currently, and it's not entirely guaranteed to solve every case (and will probably break some things too).

[dkosmari]

Should we perhaps leave the swkbd disabled by default then?

[GaryOderNichts]

Applications implementing their own screen keyboard should use the SDL_HINT_ENABLE_SCREEN_KEYBOARD hint to disable the screen keyboard instead.

[mrpapersonic]

Applications implementing their own screen keyboard should use the SDL_HINT_ENABLE_SCREEN_KEYBOARD hint to disable the screen keyboard instead.

No idea this existed, thanks!!

[dkosmari]

A quick note about using the SDL_HINT_ENABLE_SCREEN_KEYBOARD hint:

It does not produce the same result as if on-screen keyboard wasn't implemented. This is true for all ports that have an on-screen keyboard.

The culprit is SDL_VideoInit(), which checks if the video driver has on-screen keyboard support. It does not check for the hint. If on-screen keyboard is not supported by the backend, it will keep text input active by default:

    if (!SDL_HasScreenKeyboardSupport()) {
        SDL_StartTextInput();
    }

To keep the same behavior as if no on-screen keyboard exists at all, you have to do:

SDL_SetHint("SDL_HINT_ENABLE_SCREEN_KEYBOARD", "0");

SDL_Init(SDL_INIT_VIDEO);

SDL_StartTextInput();