Unable to use QML QtGamepad under Linux - qt

Question

I am unable to use QGamepad in QML under Linux.
By "unable" I mean no gamepad signal is emitted (button pressed...)
Configuration:
Ubuntu 20.04
Qt 5.15
Logitech Gamepad F310
Gamepad is well recognized by Ubuntu:
dmesg gives:
usb 1-1.6: Product: Gamepad F310
input: Logitech Gamepad F310 as /devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.6/1-1.6:1.0/input/input26
jstest-gtk recognizes gamepad well:
Logitech Gamepad F310
Device: /dev/input/js0
and is responsive when pressing buttons
Sample QML code:
import QtQuick 2.15
import QtGamepad 1.15
Rectangle {
width: 320
height: 240
Gamepad {
onButtonAChanged: {
console.log("ButtonA")
}
onButtonBChanged: {
console.log("ButtonB")
}
}
}
I tried to define QT_GAMEPAD and QT_GAMEPAD_DEVICE env variables, but without any improvment.
export QT_GAMEPAD=evdev
export QT_GAMEPAD_DEVICE=/dev/input/js0
Note: the same QML code is working well under MS Windows 10 (same Qt version).

Answer 1

Thanks to Jack White this is the solution:
Property deviceId of Gamepad module shall be initialized, using GamepadManager.
import QtQuick 2.15
import QtGamepad 1.15
Rectangle {
width: 320
height: 240
Gamepad {
deviceId: GamepadManager.connectedGamepads.length > 0 ? GamepadManager.connectedGamepads[0] : -1
onButtonAChanged: {
console.log("ButtonA");
}
onButtonBChanged: {
console.log("ButtonB");
}
}
}