xous-core/services/content-plugin-api/src/lib.rs

#![cfg_attr(target_os = "none", no_std)]

use xous::{send_message, Message, ScalarMessage, CID};

#[derive(Debug)]
pub enum Opcode {
    /// request a redraw of our canvas
    Redraw,
}

impl core::convert::TryFrom<&Message> for Opcode {
    type Error = &'static str;
    fn try_from(message: &Message) -> Result<Self, Self::Error> {
        match message {
            Message::Scalar(m) => match m.id {
                0 => Ok(Opcode::Redraw),
                _ => Err("SHCH api: unknown Scalar ID"),
            },
            _ => Err("SHCH api: unhandled message type"),
        }
    }
}

impl From<Opcode> for Message {
    fn from(opcode: Opcode) -> Message {
        match opcode {
            Opcode::Redraw => Message::Scalar(ScalarMessage {
                id: 0,
                arg1: 0,
                arg2: 0,
                arg3: 0,
                arg4: 0,
            }),
            // _ => panic!("SHCH api: Opcode type not handled by From<Opcode>, refer to helper method"),
        }
    }
}

pub trait ContentCanvasApi {
    fn redraw_canvas(&self) -> Result<(), xous::Error>;
}

pub struct ContentCanvasConnection {
    pub connection: Option<CID>,
    pub redraw_id: Option<usize>,
}

impl ContentCanvasApi for ContentCanvasConnection {
    fn redraw_canvas(&self) -> Result<(), xous::Error> {
        if let Some(id) = self.redraw_id {
            match self.connection {
                Some(cid) => send_message(cid, Message::new_scalar(id, 0, 0, 0, 0)).map(|_| ()),
                _ => Err(xous::Error::UseBeforeInit),
            }
        } else {
            Err(xous::Error::UseBeforeInit)
        }
    }
}