[Input] Get mapped joy events for joypad

[MJacred]

Get the buttons and axes mapped to the connected joypad w/o having to use them all.

Motivation behind this PR:

• I want the user to be able to change their mappings in-game. This requires knowledge about the capabilities of their connected joypad. It also allows me to fetch a different joypad image.
  • different joypads have different buttons/axes available: some joypads have JOY_BUTTON_PADDLE_*, some don't. Some don't have JOY_BUTTON_MISC1, or JOY_AXIS_RIGHT_*, etc.
• Using the joypad name is not reliable, as the same joypad can have different names on different platforms/APIs.
  • the guid is also not sensible

See attached test project:
joypad-event-test.zip

Output for my joypad using the test project:

Xbox 360 Controller
["a", "b", "x", "y", "back", "guide", "start", "leftstick", "rightstick", "leftshoulder", "rightshoulder", "dpup", "dpdown", "dpleft", "dpright"]
["leftx", "lefty", "rightx", "righty", "lefttrigger", "righttrigger"]

[MJacred]

@akien-mga: Could I get a review on this, please? :)

[AThousandShips]

People are just coming back from the holidays, most people were either still away or just coming back last week, people should be able to review this in the following week

[MJacred]

@AThousandShips as the feature freeze has been put in place, can we get this queued for 4.5, please…?
And a review, if possible.

[AThousandShips]

It'll be put on a specific milestone when reviewed, for example 4.5, but not before, the relevant teams have been notified but we're busy with 4.4 so will probably not be a priority until after releasing

[Calinou]

Tested locally on Linux, it works as expected.

Xbox One Elite 2 Controller
["a", "b", "x", "y", "back", "guide", "start", "leftstick", "rightstick", "leftshoulder", "rightshoulder", "dpup", "dpdown", "dpleft", "dpright"]
["leftx", "lefty", "rightx", "righty", "lefttrigger", "righttrigger"]

However, if your goal is to show correct button prompts or gamepad images, I think #89193 is more suited. There isn't a lot of variance in buttons across modern controllers nowadays. I think the only exception that really matters in games are the lack of analog triggers on Switch controllers (which #89193 can take into account).

Personally, I would prefer #89193 to be merged first, then wait and see if we really need to do something more before we go forward with this PR.

[MJacred]

Thanks, didn't know about that PR :)
I have a few busy weeks ahead, afterwards, I'll re-evaluate my PR

[MJacred]

@Calinou: after looking at that PR, I must say it does not satisfy my requirements.
I have a generic controller called "Wireless Gamepad F710" which follows the playstation layout, for which no name check would match, and no scheme would be returned. Therefore, I won't know about the joypad's abilities.
But let's take a more interesting case: say I had one xbox controller with paddles, and one xbox controller without. The other PR wouldn't help me learn which buttons the joypad actually has/supports (i.e. which has paddles?).

Moreover, relying on the device name is not reliable at all (depending on the OS/driver, you get different names for the same device), though I still see value in the other PR in the sense that it helps me localizing the button/axes names, provided all the constant strings are visibly documented outside the codebase.

In that sense, I'd say the two PRs actually harmonize with each other.

EDIT: Just to give a bit more context, I also want to provide several joypad button/axes to action default mappings, then auto-select the most fitting one on first connect (and more supporting features)

[MJacred]

Personally, I would prefer #89193 to be merged first, then wait and see if we really need to do something more before we go forward with this PR.

@Calinou: I hope I could convey my requirements better in my previous comment. Did it change how you feel about this PR?

[Calinou]

@Calinou: I hope I could convey my requirements better in my previous comment. Did it change how you feel about this PR?

I'm still undecided on this. I haven't seen much prior art of this in other engines/games where things like paddles are detected and bound automatically if present.

[MJacred]

Fair enough. Though I would also use this code to give warnings if their connected joypad does not have some mandatory/preferred buttons/axes, e.g. has only one (or none) joystick and 2 are required (or preferred) - I know most have them, but some people like using retro controllers whenever possible.

Until this PR's future is decided I can do a custom build, keeping this change compatible is easy enough.