Glasses

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session.glasses reports on the glasses hardware: battery level plus charging state, and whether the glasses are connected. Both are subscriptions, so you get a callback whenever the value changes.

src/background/index.ts

session.glasses.onBattery(({ level, charging }) => {
  if (level <= 15 && !charging) {
    session.display.render([{type: "text", id: "msg", box: {x: 0, y: 0, w: 576, h: 288}, text: "Glasses battery low"}]);
  }
});

There’s no synchronous getter for the current value. You learn the state by subscribing and waiting for the first event.

Battery

onBattery fires when the glasses report a new battery reading.

session.glasses.onBattery((data) => {
  console.log(`${data.level}%`, data.charging ? "charging" : "on battery");
});

Each BatteryData has:

Field	Type	Notes
`level`	`number`	Battery percentage, 0 to 100.
`charging`	`boolean`	Whether the glasses are charging.

Connection

onConnection fires when the glasses connect or disconnect.

session.glasses.onConnection((data) => {
  if (!data.connected) {
    // The glasses dropped. Display calls won't reach the HUD until they return.
  }
});

Each ConnectionData has:

Field	Type	Notes
`connected`	`boolean`	Whether the glasses are currently connected.
`modelName`	`string?`	Glasses model name, when reported. May be absent.

modelName is optional, so guard for it before reading:

session.glasses.onConnection(({ connected, modelName }) => {
  if (connected && modelName) {
    console.log(`Connected to ${modelName}`);
  }
});

Cleaning up

Both methods return an unsubscribe function:

const off = session.glasses.onBattery(handler);
off(); // stop listening

session.glasses covers the glasses hardware. The phone has its own battery and connection events on session.phone. For what the connected glasses can do (display, camera, sensors), read session.capabilities once the session is ready.

Getting Started

Core Concepts

UI Layer

Display

Audio & Speech

Sensors & Input

Camera

Phone & System

Data

Reference

Battery

Connection

Cleaning up

​Battery

​Connection

​Cleaning up

Battery

Connection

Cleaning up