How do devices work? ​

Devices can be found within the Rust code of this app. As an example, we'll be using the Capellix device. Teaching you Rust is beyond this tutorial's scope. I assume you already have some amount of Rust knowledge.

Devices have 2 base traits that let the app work with them - Device and DeviceCreator. The latter handles creating the device object and setting it up to connect to the device, the former handles the day-to-day operations of the device.

The devices themselves are stored in a Box<dyn Device> that dynamically dispatches calls to the appropriate connected device.

Table of Contents ​

The DeviceCreator trait. ​

To successfully create and connect to a device, the app must know how to bootstrap everything required for it to function. This may be various API handles, counters, or other related items.

pub trait DeviceCreator {
    fn new() -> Result<Self, &'static str>
    where
        Self: Sized;
    fn device_info() -> DeviceInfo
    where
        Self: Sized;
}

The Device trait. ​

Devices must implement 4 key functions:

pub trait Device {
    fn init(&mut self) -> Result<(), &'static str>;
    fn close(&mut self) -> Result<(), &'static str>;
    fn reopen(&mut self) -> Result<(), &'static str>;
    fn send_image(&mut self, img: &[u8]) -> Result<(), &'static str>;
}