Feature Request: Add a better way to create a Joystick Report.

[aspizu]

Add a better way to create a Joystick Report.

[aspizu]

This is how you can create a Joystick Report with two analog sticks and 8 buttons.

/// JoystickReport describes a report and its companion descriptor that can be
/// used to send joystick movements and button presses to a host.
#[gen_hid_descriptor(
    (collection = APPLICATION, usage_page = GENERIC_DESKTOP, usage = JOYSTICK) = {
        (collection = APPLICATION, usage = POINTER) = {
            (usage = X,) = {
                #[item_settings data,variable,absolute] x=input;
            };
            (usage = Y,) = {
                #[item_settings data,variable,absolute] y=input;
            };
            (usage = 0x33,) = {
                #[item_settings data,variable,absolute] rx=input;
            };
            (usage = 0x34,) = {
                #[item_settings data,variable,absolute] ry=input;
            };
        };
        (usage_page = BUTTON, usage_min = BUTTON_1, usage_max = BUTTON_8) = {
            #[packed_bits 8] #[item_settings data,variable,absolute] buttons=input;
        }
    }
)]
#[allow(dead_code)]
pub struct JoystickReport {
    pub x: i8,
    pub y: i8,
    pub rx: i8,
    pub ry: i8,
    pub buttons: u8,
}

usage:

let report = JoystickReport {
    x: X,
    y: Y,
    rx: RX,
    ry: RY,
    buttons: BUTTON_1
        | BUTTON_2 << 1
        | BUTTON_3 << 2
        | BUTTON_4 << 3
        | BUTTON_5 << 4
        | BUTTON_6 << 5),
};
hid_writer.write_serialize(&report).await.unwrap();

[twitchyliquid64]

We already have KeyboardReport, but if you want to send a PR with the above to add in JoystickReport, im down for that!

I dont think it gets much simpler I'm afraid

[vic1707]

Pretty new to this world, sorry if its a stupid question.

Is there a way to compose reports from other reports or using substructs?

Having the final report struct looking like this is really appealing

pub struct GamepadReport {
    pub left_joystick: Joystick,
    pub right_joystick: Joystick,
    /// (A, B, X, Y, L, R), one bit per button
    pub buttons: u8,
}

pub struct Joystick {
    /// Horizontal axis
    pub x: i8,
    /// Vertical axis
    pub y: i8,
}

[twitchyliquid64]

No worries at all Victor!

Talking in vague generalities: with HID you are usually talking to a computer that expects exactly some format for the HID data coming in. Unfortunately that means we usually have to follow what the spec suggested for things like joysticks. OS code implementing HID is trash, so its common that even stuff that should work doesn't on something like (cough) windows.

As for composing the report struct using usbd-hid: unfortunately the code does not support nested structs - you need to unravel all the fields into one struct.

[vic1707]

Thanks for the explanation! no composition it is 👍
I would have never thought that windows could be problematic, Microsoft would never do that xD