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subwave-nowplaying/README.md
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# subwave-nowplaying
Tronbyt/Tidbyt app showing the current track on a [SUB/WAVE](https://github.com/perminder-klair/subwave)
internet radio station: album art, and four scrolling lines — track
title/artist, a thin separator, the current show and host, and local
time/temperature — plus a track progress bar pinned to the bottom of the
32px-wide text column. Color scheme (cyan title/artist, white show name,
magenta host/progress bar) is loosely modeled on SUB/WAVE's own web
now-playing display.
Not tied to any specific station — set your own station's base URL in the
app's config when adding it to a device.
## Configuration
- **Station URL** — the base URL of your SUB/WAVE instance, e.g.
`https://radio.example.com`. No trailing slash needed (stripped
automatically). No auth required — SUB/WAVE's now-playing and cover-art
endpoints are public.
## How it works
- `GET {station_url}/api/now-playing` — track title, artist, `subsonic_id`,
DJ/station name, and stream online status. Cached 20s.
- `GET {station_url}/api/cover/{subsonic_id}` — album art JPEG, proxied by
SUB/WAVE itself (no Navidrome credentials needed). Cached 300s.
- If the station reports `streamOnline: false`, shows "<station> offline"
instead of stale track info.
- If a track has no `subsonic_id`, or the cover fetch fails, falls back to a
full-width layout with no art rather than a broken image.
- Shows the current show name (`context.activeShow.name`) and host name
(`dj.name`) below the artist, separated by a thin divider line, and the
local time/temperature (`context.clock`/`context.weather`) below that —
all as independently scrolling Marquee lines, confined to the 32px-wide
text column next to the album art (no overlay/overlap with the art).
**Known quirk — occasional Marquee glitch:** pixlet's `render.Marquee` runs
its own internal scroll-cycle animation, and stacking several Marquees of
different text lengths in one Root can occasionally desync them — a line
may briefly blank or show a garbled frame while another Marquee is
mid-cycle. This is a real, currently-unfixed pixlet bug (there's an
open `FIXME: Behaviour when children themselves are animated is a bit
weird` in pixlet's own widget docs), not something introduced by this app.
It's also not unique to this app: `tronbyt/apps/apps/goosefm/goose_fm.star`
(an accepted official community app) stacks 3 Marquees for the same kind of
now-playing info and exhibits the identical occasional glitch on close
frame-by-frame inspection. In practice it's subtle enough to be easy to
miss on a real, continuously-scrolling display. A custom hand-rolled scroll
(via `animation.Transformation` + `Translate`, avoiding `Marquee` entirely)
was prototyped and could fully eliminate this, but only by consolidating
down to 2 scrolling lines total (title alone, everything else combined into
one line) — full independent lines for every field was preferred instead,
accepting the same minor quirk real Tidbyt/Tronbyt apps already ship with.
**Progress bar caveat:** the now-playing API reports track `duration` but
not elapsed/remaining time, so the app tracks playback position itself —
the first time it sees a given `subsonic_id`, it stamps the current
wall-clock time in pixlet's cache, then diffs against that stamp on later
renders to compute elapsed seconds. This only works correctly on a
long-lived server process with a persistent cache (true for
`tronbyt/server`'s in-memory cache) — a one-shot `pixlet render` CLI
invocation always starts a fresh process with an empty cache, so the bar
will always show 0% when testing locally. This is expected, not a bug.
**Note on unreachable hosts:** if the station URL is wrong or the host is
completely unreachable (DNS failure, connection refused), `http.get` raises
a hard error and the render fails for that cycle — this is normal pixlet/
Starlark behavior (no try/except in the language), not a bug. Only
HTTP-level errors (404, 500, etc.) are something the app can catch and
display a message for, which it does.
## Dev/test
```
pixlet render subwave_nowplaying.star station_url=https://your-station.example.com
pixlet serve subwave_nowplaying.star
```
## Deploy
Upload `subwave_nowplaying.star` directly through your Tronbyt server's
"Upload app" button on a device's Add App page (single file, no bundled
assets — no need to zip). Configure the Station URL field when adding it to
your device's schedule.