1# llimphi-widget-waveform
2
3**Live waveform** viewer.
4
5The pattern is analogous to `llimphi-widget-timeline`: the widget keeps **no
6audio state** (no cpal, no `AudioProbe`, no ring buffer). The caller passes a
7`Fn(&mut Vec<f32>) -> u16` closure that fills a buffer with the latest samples
8and returns how many **interleaved channels** it carries; the widget folds to
9mono and draws a **min/max envelope per column** (a closed polygon with a faint
10fill plus a stroke above and below) over a **centre line** always present as the
11viewer's "ground". No mouse handlers — paint only.
12
13```text
14  ┌─────────────────────────────────────────────────┐
15  │   ▄▄▄    ▄  ▄▄▄  ▄▄    ▄▄  ▄                    │
16  │  ▄███▄  ▄█▄▄███▄▄██▄▄▄▄██▄▄█▄                   │
17  │──█████──███████████████████████─── centre ──────│
18  │  ▀███▀  ▀█▀▀███▀▀██▀▀▀▀██▀▀█▀                   │
19  │   ▀▀▀    ▀  ▀▀▀  ▀▀    ▀▀  ▀                    │
20  └─────────────────────────────────────────────────┘
21```
22
23Typical use (a player with an audio probe):
24
25```ignore
26use std::sync::Arc;
27let probe = audio_probe();        // the app's own Arc<AudioProbe>
28let palette = WaveformPalette::default();
29waveform_view(
30    move |out| {
31        let (_sr, ch) = probe.snapshot(out);
32        ch                         // interleaved channels
33    },
34    &palette,
35)
36```
37
38If the closure returns `0` channels (or does not fill the buffer), the widget
39paints only the centre line — useful to show "viewer alive, no signal" while the
40capture device has not come up yet.
41
42---
43
44Part of **llimphi** — see [llimphi](../../README.md).