Joypad and joystick support

[bjorndm]

I am not sure but for portable game engines we will also need joystick and joypad support. Please consider it.

[kanryu]

@bjorndm Yes, glfw is known to have pretty strong joystick support.

I just checked the source code, and it seems that gioui does not include joystick support. Therefore, it is necessary to port all glfw joystick implementations.

However, the original purpose of mado is window control and support for rendering engines including OpenGL. Joystick support will come later.

I'll be happy to check it out if you send me a PullRequest.

[bjorndm]

I can probably help with a joystick driver for Linux/Android in pure Go. On that platform it boils down to reading a device file.

[kanryu]

The purpose of mado is to have the same behavior as glfw, and some code is already implemented in glfw/input.go and glfw/joystick.go.

Joystick support in glfw is a highly independent feature, and you can easily identify the implementation location by searching the source code for '_glfwInputJoystick'.
On Linux, it seems to simply read the device file at /dev/event[0-9].
If you can read the C language source code, I think porting is quite possible.

I look forward to your activities. :)