Module now_playing 

The now-playing banner: a core-owned, transient announcement of the current track (ADR-0110, Plan 0097).

A shell pushes in a UTF-8 string and nothing else — SMTC on the standalone, foobar’s titleformat through the C ABI — and everything downstream of that string is decided here: the fade envelope, the artist/title split, the placement, and the truncation rule. That is the whole point of the ADR: two frontends whose metadata sources have nothing in common cannot drift on what a track change looks like, because neither of them draws it.

The envelope is a pure function of accumulated dt (Plan 0014’s injected real seconds), so it runs for the same wall-clock duration on a 60 Hz and a 165 Hz display and is testable without a GPU. Nothing here reads a clock.

This module is not behind the text feature. A build without it keeps the state and simply never asks for a layout, which is what lets the plugin build turn the feature on without touching any of this.

Structs

BannerLine

One positioned line of the banner, ready to become a TextRun. The Cow borrows the stored string whenever the line fits and owns only the truncated copy, so a steady banner frame allocates nothing.

NowPlaying

The banner’s whole state: what to announce, and how long ago it was set.

Constants

FADE_IN_SECS

Seconds the banner takes to reach full opacity.

FADE_OUT_SECS

Seconds the banner takes to fade back out.

HOLD_SECS

Seconds the banner holds at full opacity.

SEPARATOR

The separator a shell puts between artist and title. Both sources agree on it: the plugin renders %artist% - %title% (ADR-0110) and the standalone joins its SMTC fields the same way, so this one rule splits both.

TOTAL_SECS

Total lifetime of one announcement, after which nothing is drawn.

Functions

alpha_at

The envelope: ramp in, hold, ramp out, then nothing. A pure function of elapsed seconds, which is what makes it identical at any refresh rate and testable without a device.