API reference

Glasses functions are imported from the mira WebAssembly module; phone methods live on miraCompanion. Arguments and return values are 32-bit integers unless noted.

Exports

Your module exports memory and these functions. None of them return a value.

app_init()

Called once when the app opens.

app_render(elapsed_ms)

Called repeatedly while the app runs, with the milliseconds since the previous call.

app_event(event)

Called with an input event. See Input.

app_stop()

Called right before the app closes.

Frames

begin()

Starts a new frame.

present()

Shows the frame. Only changed areas repaint.

frame_checkpoint() → i32

Saves everything drawn so far in this frame.

frame_restore() → i32

Restores the last checkpoint. Returns 0 when there’s nothing to restore.

Shapes

Coordinates are pixels on the 640 × 480 canvas. gray is 0 to 15.

line(x0, y0, x1, y1, width, gray)

A line.

fill_rect(x, y, w, h, gray)

A filled rectangle.

stroke_rect(x, y, w, h, line, gray)

A rectangle outline.

fill_round_rect(x, y, w, h, radius, gray)

A filled rounded rectangle.

stroke_round_rect(x, y, w, h, radius, line, gray)

A rounded rectangle outline.

fill_circle(cx, cy, radius, gray)

A filled circle.

stroke_circle(cx, cy, radius, line, gray)

A circle outline.

fill_triangle(x0, y0, x1, y1, x2, y2, gray)

A filled triangle.

Text and images

text(x, y, w, h, gray, font, align, line_spacing, utf8, len)

UTF-8 text clipped to its box. Fonts 0 to 3 are 24, 18, 32 and 40 px; align 0 left, 1 center, 2 right.

bitmap4(x, y, w, h, pixels, len)

A 4-bit grayscale image. Rows are ceil(w / 2) bytes, left pixel in the high nibble. Gray 15 is transparent.

bitmap4_rotated(x, y, w, h, pixels, len, degrees)

The same image rotated around its center.

bitmap1(x, y, w, h, mask, len, gray)

A one-color mask up to 32 × 32. Rows are ceil(w / 8) bytes, most significant bit first.

Device

now_ms() → i32

A millisecond clock for timing.

device_status(out, capacity) → i32

Writes 10 bytes: battery, charging, audio link, phone link, clock set, hour, minute, month, day, weekday. See Device and media.

display_brightness_get() → i32

Brightness in percent.

display_brightness_set(percent) → i32

Sets brightness from 0 to 100 and returns the value applied.

display_power_get() → i32

1 while the display is awake, 0 while it’s asleep.

display_power_set(on)

1 wakes the display or resets its idle timer; 0 sleeps it.

media_state(out, capacity) → i32

Available and playing bytes, then null-terminated title and artist. Use a 164-byte buffer.

media_command(command) → i32

0 previous, 1 play or pause, 2 next, 3 volume up, 4 volume down.

audio_level(channel) → i32

Loudness from 0 to 255. Channel 0 is the microphone, 1 is MIRA’s spoken replies.

Head tracking

Angles are centidegrees. Reading orientation or raw motion pauses the look-up dashboard until imu_stop().

imu_yaw_cdeg() → i32

Heading. Positive turns right.

imu_pitch_cdeg() → i32

Tilt. Positive looks up.

imu_roll_cdeg() → i32

Roll.

imu_ready() → i32

1 once calibrated data has arrived. Call a getter first.

imu_threshold(above_cdeg, below_cdeg) → i32

1 above, 0 below, -1 not ready, -2 full tracking active elsewhere. Leaves the dashboard working.

imu_raw_read(out) → i32

Nine 32-bit floats: accelerometer, gyroscope, magnetometer. Returns 1 when fresh.

imu_stop()

Releases head tracking.

Phone requests

ble_request asks the MIRA app on the phone to do work the glasses can’t, such as live transcription. It returns a request ID right away; poll for the answer on later frames.

ble_request(method, payload, len) → i32

Sends a request and returns its ID. Up to 8 can be in flight, with payloads up to 384 bytes.

ble_response_len(id) → i32

The response size once it’s ready. -1 pending, -2 unknown ID, -3 timed out after 8 seconds. Phone-side errors come back as -100 - status.

ble_response_read(id, out, capacity) → i32

Copies the response, which can be read once. -4 means the buffer is too small.

Rust helpers

The guide includes shared Rust modules. These are the ones most apps use.

content::cursor(x, y, visible)

Points the shared cursor at your focused control.

content::double_tap_local(claim)

Delivers double tap to your app instead of opening the sidebar.

content::holds_local(claim)

Delivers long press, hold start and hold end to your app.

content::sidebar_open() → bool

True while the sidebar covers your app.

content::overlay_visible() → bool

True while a notification or the dashboard covers your app.

content::context_changed() → bool

True when either of the above changed since you last asked.

content::imu::stop()

Same as imu_stop().

companion::Companion::new(name)

The ordered message bridge to your phone companion. tick(elapsed) returns the next message once; send(json) returns false while busy.

companion::Realtime::new(name)

The latest-value channel paired with setLatestForApp. Call tick every frame.

retained_frame::start(changed) / checkpoint()

Keeps static drawing between frames.

app_icon!(…)

Defines the 32 × 32 sidebar icon.

Phone companion

Methods on miraCompanion. Unless noted, each returns a promise.

sendToApp(value)

Sends an ordered JSON message to the glasses, up to 3,500 bytes.

setSnapshotForApp(value)

Replaces pending state the glasses page through, up to 3,500 bytes.

setLatestForApp(value)

Sets small realtime state, up to 380 bytes. Only the newest value is kept.

onFromApp(handler) → unsubscribe

Calls handler(message) for each message from the glasses. Not a promise.

storeGet(key) / storeSet(key, value) / storeRemove(key)

Small string storage on the phone.

getMediaState() / mediaCommand(code)

What’s playing, and playback controls.

getIMU() / stopIMU()

Motion readings from the glasses, and releasing them.

startCapture() / stopCapture()

Starts and stops glasses microphone audio.

onCapture(handler) → unsubscribe

Receives audio frames. Not a promise.

bindPasteButton(button, onPaste)

Shows the iOS Paste control over a button. Returns {ready, dispose()}.

fetch(input, init) / WebSocket

Standard networking, made from the phone.