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musicmouse/slint-frontend/ui/theme.slint
Martin Bauer 6ccb3e458f Add a native Slint front-end for the music player
The React UI is sluggish on the kiosk and the reasons are browser-shaped: a compositor
deciding what gets its own layer, a requestAnimationFrame loop repainting the viewport,
and a JPEG decode per album card per cold start. The last three commits chased that
through the service worker and the cover pipeline. This is the other direction - the
same backend, the same layout, the same German copy, without a browser.

Browse and play only. The typing game, the room-lights page, parent mode and the
IR-remote assignment stay web-only, and nothing here touches python-backend.

Four things carry the performance claim, in rough order of how much they should matter:

Covers are downscaled once, ever. The backend serves one size - 640px on the long edge,
no ?size= - and a grid card is 180. src/covers.rs fetches each cover once on a worker
thread, resizes it, and writes a JPEG thumbnail to ~/.cache/musicmouse-slint/covers/.
Two tiers and only two, which is what makes the cache worth keeping: a per-widget pixel
size would give each album a dozen near-identical files and a fresh decode for each. The
cache is dropped when the websocket announces a rescan, because that is the one moment
the backend rewrites the art behind an unchanged cover URL - the trap sw.js had to learn
about the hard way.

The grid is virtualized. Rust hands the UI the album list pre-chunked into rows and the
view puts those in a ListView, which instantiates only what is on screen. A flat list of
660 cards gives it no rows to skip, hence the chunking. Same purpose as
content-visibility: auto on .grid > .card.

The progress bar animates between the 2 Hz pushes rather than running a clock, so
interpolation costs a property evaluation per frame on the render side and there is no
equivalent of usePlaybackClock. It is suppressed for the frame a track changes on, so a
new track jumps instead of sliding across two unrelated positions.

Nothing on screen animates by itself. The ambient canvas is not ported, for the reason
lib/lowPower.ts already gives: a loop repainting the viewport is a floor you cannot get
under while it runs at all.

The device must not use FemtoVG. On Mesa V3D it draws every runtime-loaded Image as
solid black (slint-ui/slint#11785, open), which here means every album cover; Skia and
the software renderer are unaffected. So `kiosk` is linuxkms + Skia and FemtoVG stays
the default only for desktop development. Both profiles are verified to build; the kiosk
binary links libinput/libgbm/libdrm and no X11 or Wayland at all.

lib/search.ts, lib/keyboard.ts and lib/format.ts were already pure functions with their
own tests, so they port across as pure Rust with theirs: 43 tests, no window required.
The .slint files are layout only - nothing in them formats a number or picks a word.

Verified against the real 660-album library rather than a fixture. tools/headless-shots.sh
renders the UI inside a nested headless compositor and grabs a frame per screen, which
is how that was checked on a machine whose session was locked; a Slint window needs a
real compositor, and under bare Xvfb nothing maps at all.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
2026-09-20 22:26:09 +02:00

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// The palette, converted once from the web front-end's oklch tokens
// (`web/src/styles/app.css`) into the sRGB hex Slint speaks. The oklch source value is
// kept beside each one, because that is the form the design is actually maintained in -
// if a colour needs adjusting, adjust the oklch and re-convert (`src/oklch.rs`), rather
// than nudging the hex and letting the two drift.
export global Theme {
// ------------------------------------------------------------------ colours --
out property <color> ink: #113339; // oklch(30% 0.04 210)
out property <color> paper: #eef7f9; // oklch(97% 0.01 210)
out property <color> accent: #de73bd; // oklch(70% 0.16 340)
out property <color> accent-dim: #f292d3; // oklch(78% 0.14 340)
out property <color> sea-deep: #001b21; // oklch(20% 0.045 210)
out property <color> shadow: #001017; // oklch(15% 0.05 210)
// The stage gradient, which in the web app sits under an animated canvas. There is
// no canvas here: a full-viewport repaint loop is the one cost a Pi cannot absorb,
// and `?pi=1` already removes it on the device this replaces.
out property <color> stage-top: #397d88; // oklch(55% 0.07 210)
out property <color> stage-mid: #0e4b54; // oklch(38% 0.06 210)
out property <color> text-dim: #c9dbdf; // oklch(88% 0.02 210)
out property <color> text-sub: #c0d2d5; // oklch(85% 0.02 210)
out property <color> count-pink: #7d0563; // oklch(40% 0.17 340)
out property <color> card-music: #e4f1f4; // oklch(95% 0.015 210)
out property <color> card-book: #ffd5ab; // oklch(92% 0.09 55)
out property <color> book-edge-1: #ffc298; // oklch(86% 0.09 55)
out property <color> book-edge-2: #e5a880; // oklch(78% 0.09 55)
out property <color> bar-bg: #00171e; // oklch(18% 0.05 210)
out property <color> sheet-bg: #e9f4f6; // oklch(96% 0.012 210)
out property <color> backdrop: #000e12; // oklch(15% 0.03 210)
// Two track colours, not one with an alpha: the seek bar sits on the pale stage in
// the play view and on the near-black player bar in the browse view, and a single
// translucent fill that reads correctly on one is invisible on the other.
out property <color> progress-track: #1b3236; // oklch(30% 0.03 210)
out property <color> progress-track-dark: #2e4f57;
out property <color> vol-empty: #c9dbdf; // oklch(88% 0.02 210)
// Glass, without the glass. `backdrop-filter` has no counterpart here, so these are
// exactly the web app's own `data-blur="off"` fallback: a flat translucent fill.
// That is a real loss of depth and the honest substitute for it - faking a blur by
// compositing a pre-blurred copy would reintroduce the per-frame cost the blur was
// dropped to avoid.
out property <brush> glass: @linear-gradient(160deg, #eef7f924 0%, #eef7f90d 100%);
out property <color> glass-border: #eef7f929;
out property <color> row-idle: #f7fcfd1a;
out property <color> row-active: #f7fcfd38;
// ------------------------------------------------------------------- metrics --
out property <length> radius-panel: 22px;
out property <length> radius-card: 16px;
out property <length> radius-row: 12px;
out property <length> radius-sheet: 26px;
out property <length> pill: 999px;
// The album grid's track width. The web grid is `minmax(180px, 1fr)`; keeping the
// same number keeps the same number of columns at 1920, which is what the shelf
// rows and the measured card height below were both tuned against.
out property <length> card-width: 180px;
out property <length> grid-gap: 24px;
out property <length> shelf-tile: 148px;
// How much of the right edge the page must leave clear for nothing to render
// underneath the corner controls.
out property <length> rail-clearance: 88px;
// ---------------------------------------------------------------- typography --
// Heavy throughout: 700/800/900. Durations and counters use the monospace family so
// a ticking clock does not reflow the row it sits in.
out property <string> font: "Nunito";
out property <string> mono: "monospace";
out property <length> text-hero: 44px;
out property <length> text-title: 26px;
out property <length> text-heading: 20px;
out property <length> text-body: 16px;
out property <length> text-small: 13px;
out property <length> text-tiny: 12px;
}