Tauri Events

Some widgets need to react to system changes (e.g., media playback, system audio samples). For this, Delta Widgets exposes Tauri events that you can subscribe to.

media_updated

To listen for changes in the currently playing system media, first invoke start_media_listener_cmd. Once the listener is active, the application emits the media_updated event whenever media metadata or playback status changes.

The media_updated event acts as a notification trigger. To retrieve the latest media information, call get_media inside the event listener.

Example: Listening to media_updated

import { invoke, listen } from "@tauri-apps/api/core";

async function setup() {
  // Start media listener
  await invoke("start_media_listener_cmd");

  // Get initial media metadata
  console.log(await invoke("get_media"));

  // Listen for subsequent media updates
  await listen("media_updated", async () => {
    console.log(await invoke("get_media"));
  });
}

setup();

This ensures your widget updates whenever the media session changes.

audio-samples

After starting system audio capture with start_audio_capture, the application begins emitting the audio-samples event at roughly 33 ms intervals.

Each audio-samples event returns an array of approximately 256 numeric sample values representing the current system audio waveform.

Example: Listening to audio-samples

import { invoke, listen } from "@tauri-apps/api/core";

async function setup() {
  // Start capturing system audio
  await invoke("start_audio_capture");

  // Receive waveform samples continuously
  await listen<number[]>("audio-samples", (event) => {
    console.log(event.payload);
  });
}

setup();