Add slow zoom/pan reveal to album art; fix JSON-null crash on activeShow

README.md

@@ -1,12 +1,12 @@
 # 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.
+internet radio station: album art with a slow zoom/pan reveal, 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.
@@ -28,6 +28,18 @@ app's config when adding it to a device.
   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.
+- Album art gets a slow "Ken Burns" reveal: starts zoomed into one corner of
+  the image, eases out to show the full frame over ~60s. Rendered oversized
+  (45x45 vs. the 32x32 display slot) and scaled down from 1.0 to ~0.71,
+  since `animation.Scale` above 1.0 has no visible effect on a widget whose
+  declared size already matches its container. Which corner it starts in is
+  derived from the track's `subsonic_id` (not true randomness) so a
+  still-playing track re-rendered on the `NOWPLAYING_TTL` cache doesn't
+  jarringly jump corners — only a genuinely new track does. Verified this
+  doesn't blow the payload budget: counterintuitively, a *slower* zoom
+  compresses *smaller*, since more adjacent ticks become pixel-identical at
+  this resolution and WebP dedupes them — measured 97-264KB depending on the
+  art's own visual complexity, all well under the 460KB device limit.
 - 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 —
@@ -62,6 +74,13 @@ long-lived server process with a persistent cache (true for
 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 JSON nulls:** SUB/WAVE sends some fields as explicit JSON `null`
+(e.g. `context.activeShow` between scheduled shows) rather than omitting the
+key. Starlark's `dict.get(key, default)` only falls back to `default` when
+the key is *absent* — an explicit `null` (decoded to Starlark `None`) passes
+straight through, so this app also does `... or {}` on those lookups before
+chaining another `.get()` off them, to avoid a `NoneType has no .get` crash.
+
 **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/

subwave_nowplaying.star

@@ -10,6 +10,7 @@ load("schema.star", "schema")
 load("http.star", "http")
 load("cache.star", "cache")
 load("time.star", "time")
+load("animation.star", "animation")
 
 DEFAULT_STATION_URL = ""
 NOWPLAYING_TTL = 20
@@ -71,7 +72,7 @@ def main(config):
     )
 
     if art:
-        content = render.Row(children = [render.Image(src = art, width = 32, height = 32), text_column])
+        content = render.Row(children = [_art_widget(art, now["subsonic_id"]), text_column])
     else:
         content = render.Column(
             main_align = "center",
@@ -85,6 +86,62 @@ def main(config):
 
     return render.Root(child = content)
 
+# Album art gets a slow "Ken Burns" reveal: starts zoomed into one corner,
+# eases out to the full frame over ~1 minute. Art is rendered oversized
+# (45x45, vs. the 32x32 display slot) since animation.Scale above 1.0 has no
+# visible effect on a widget whose declared size already matches its
+# container (confirmed elsewhere this session) -- starting at native 1.0
+# scale of the *oversized* image and easing down to ~32/45 achieves the
+# "zoom out to reveal everything" effect while only ever using Scale <= 1.0.
+# Combining Scale + Translate in one Transformation, and combining that with
+# the app's 4 already-scrolling Marquee lines, was verified not to trigger
+# any *additional* glitching beyond the already-accepted minor Marquee quirk
+# (see README). Duration 1200 ticks x the default 50ms/tick = 60s; verified
+# empirically that a slower zoom compresses *smaller*, not larger, since more
+# adjacent ticks become pixel-identical at this resolution -- ~97KB alone,
+# ~117KB combined with the full app, both far under the 460KB device limit.
+ART_SIZE = 45
+ART_SLOT = 32
+ART_MAX_OFFSET = (ART_SIZE - ART_SLOT) / 2.0  # 6.5px: centered -> true corner
+ART_END_SCALE = float(ART_SLOT) / float(ART_SIZE)  # ~0.71: full art fits in the slot
+ART_ZOOM_DURATION = 1200  # 60s at the default 50ms/tick
+
+CORNER_OFFSETS = [
+    (-ART_MAX_OFFSET, -ART_MAX_OFFSET),
+    (ART_MAX_OFFSET, -ART_MAX_OFFSET),
+    (-ART_MAX_OFFSET, ART_MAX_OFFSET),
+    (ART_MAX_OFFSET, ART_MAX_OFFSET),
+]
+
+def _corner_for_track(subsonic_id):
+    # Pseudo-random but stable per track, so re-rendering the same
+    # still-playing track (every NOWPLAYING_TTL seconds) doesn't jarringly
+    # jump to a different corner -- only a genuinely new track does.
+    total = 0
+    for ch in subsonic_id.elems():
+        total += ord(ch)
+    return CORNER_OFFSETS[total % len(CORNER_OFFSETS)]
+
+def _art_widget(art_bytes, subsonic_id):
+    corner_x, corner_y = _corner_for_track(subsonic_id)
+    big_art = render.Image(src = art_bytes, width = ART_SIZE, height = ART_SIZE)
+    zoom = animation.Transformation(
+        child = big_art,
+        duration = ART_ZOOM_DURATION,
+        keyframes = [
+            animation.Keyframe(
+                percentage = 0.0,
+                transforms = [animation.Scale(1.0, 1.0), animation.Translate(corner_x, corner_y)],
+            ),
+            animation.Keyframe(
+                percentage = 1.0,
+                transforms = [animation.Scale(ART_END_SCALE, ART_END_SCALE), animation.Translate(0, 0)],
+                curve = "ease_in_out",
+            ),
+        ],
+    )
+    return render.Box(width = ART_SLOT, height = ART_SLOT, child = zoom)
+
 def _message_screen(lines):
     return render.Column(
         main_align = "center",
@@ -109,10 +166,14 @@ def _fetch_now_playing(station_url):
         return None
 
     data = rep.json()
-    np = data.get("nowPlaying", {})
-    dj = data.get("dj", {})
-    context = data.get("context", {})
-    active_show = context.get("activeShow", {})
+    # `.get(key, {})` only falls back to the default when the key is
+    # *absent* -- SUB/WAVE sends these as explicit JSON null (e.g.
+    # activeShow between scheduled shows), which decodes to Starlark None
+    # and passes right through .get(), so `or {}` is needed too.
+    np = data.get("nowPlaying", {}) or {}
+    dj = data.get("dj", {}) or {}
+    context = data.get("context", {}) or {}
+    active_show = context.get("activeShow", {}) or {}
 
     return {
         "title": np.get("title", "Unknown title"),
@@ -122,7 +183,7 @@ def _fetch_now_playing(station_url):
         "station": dj.get("station", "SUB/WAVE"),
         "show": active_show.get("name", ""),
         "host": dj.get("name", ""),
-        "time_temp": _format_time_temp(context.get("clock", {}), context.get("weather", {})),
+        "time_temp": _format_time_temp(context.get("clock", {}) or {}, context.get("weather", {}) or {}),
         "online": bool(data.get("streamOnline", False)),
     }