Add volume management to AVR

static/app.js

@@ -151,7 +151,7 @@ els('.card[data-room]').forEach((node) => {
     const direction = Number(button.dataset.delta);
     holdable(button, () => nudge(key, direction));
   });
-  if (room.meter) draggable(room);
+  draggable(room);
   seekable(room);
 
   // A cover that will not load (gone, or plain http on an https page) is
@@ -165,10 +165,7 @@ els('.card[data-room]').forEach((node) => {
   if (room.next) room.next.addEventListener('click', () => skipTrack(key, 'next'));
 });
 
-/* The volume row, which the AVR's card has not got: its own level is not in
-   /api/state, so there is nothing to draw a meter from. */
 function paintVolume(room) {
-  if (!room.meter) return;
   const known = room.volume !== null && room.volume !== undefined;
   room.level.textContent = known ? room.volume : '—';
   // The fill and the knob riding it both size themselves off this.
@@ -191,9 +188,6 @@ function paintTransport(room) {
   if (room.next) room.next.disabled = !room.available;
 }
 
-/* The Spotify buttons and the host toggle, which the AVR's card has not got:
-   those resume an account in a room, or join it to the AVR, and neither is
-   something the AVR does to itself. */
 function paintSources(room) {
   if (!room.sources) return;
   // Grouped, the room plays whatever the AVR does, so resuming Spotify on it
@@ -787,6 +781,7 @@ function render(state) {
   // play state is that device's -- HEOS has none to give for an input.
   applyRoom(rooms[HOST], {
     available: avr.connected !== false,
+    volume: avr.volume,
     now_playing: avr.now_playing || null,
     play_state: (avr.now_playing || {}).play_state || null,
   });