ei: add support for libei

src/ei/ei_ifs/ei_button.rs

@@ -0,0 +1,72 @@
+use {
+    crate::{
+        backend::KeyState,
+        ei::{
+            ei_client::{EiClient, EiClientError},
+            ei_ifs::ei_device::{EiDevice, EiDeviceInterface},
+            ei_object::{EiObject, EiVersion},
+        },
+        leaks::Tracker,
+        wire_ei::{
+            ei_button::{ClientButton, EiButtonRequestHandler, Release, ServerButton},
+            EiButtonId,
+        },
+    },
+    std::rc::Rc,
+    thiserror::Error,
+};
+
+pub struct EiButton {
+    pub id: EiButtonId,
+    pub client: Rc<EiClient>,
+    pub tracker: Tracker<Self>,
+    pub version: EiVersion,
+    pub device: Rc<EiDevice>,
+}
+
+ei_device_interface!(EiButton, ei_button, button);
+
+impl EiButton {
+    pub fn send_button(&self, button: u32, state: KeyState) {
+        self.client.event(ServerButton {
+            self_id: self.id,
+            button,
+            state: state as _,
+        });
+    }
+}
+
+impl EiButtonRequestHandler for EiButton {
+    type Error = EiButtonError;
+
+    fn release(&self, _req: Release, _slf: &Rc<Self>) -> Result<(), Self::Error> {
+        self.destroy()?;
+        Ok(())
+    }
+
+    fn client_button(&self, req: ClientButton, _slf: &Rc<Self>) -> Result<(), Self::Error> {
+        let pressed = match req.state {
+            0 => KeyState::Released,
+            1 => KeyState::Pressed,
+            _ => return Err(EiButtonError::InvalidButtonState(req.state)),
+        };
+        self.device.button_changes.push((req.button, pressed));
+        Ok(())
+    }
+}
+
+ei_object_base! {
+    self = EiButton;
+    version = self.version;
+}
+
+impl EiObject for EiButton {}
+
+#[derive(Debug, Error)]
+pub enum EiButtonError {
+    #[error(transparent)]
+    EiClientError(Box<EiClientError>),
+    #[error("Invalid button state {0}")]
+    InvalidButtonState(u32),
+}
+efrom!(EiButtonError, EiClientError);