"""Decides what should be on screen right now, renders it, and only pushes to the panel when the rendered image actually changed. Design goals (in reaction to the InkyPi issues that motivated this rewrite): - One short tick (a few seconds), not a long sleep-until-interval -- config changes and manual actions take effect almost immediately, no signaling machinery needed. - Navidrome can preempt the rotation the instant something's playing, without needing to be "its turn" in a round-robin. - A screen is only ever fully re-rendered+pushed to hardware when its rendered image differs from what's currently displayed. """ import hashlib import logging import threading import time from datetime import date from pathlib import Path from PIL import Image logger = logging.getLogger(__name__) TICK_SECONDS = 5 PREVIEW_PATH = Path(__file__).resolve().parent / "web" / "static" / "preview.png" class ScreenCache: """Remembers a screen's last check() result so we don't re-poll faster than its own poll_interval, even if the rotation/tick cadence is tighter.""" def __init__(self): self.state = None self.checked_at: float = 0.0 self.checked_date: date | None = None def is_stale(self, poll_interval: int) -> bool: # Also stale across a local-midnight rollover, independent of # poll_interval -- otherwise a screen whose data is inherently # date-bound (weather's daily forecast labels, its "today" hourly # graph) keeps showing yesterday's data for up to poll_interval # after midnight, since the cached state was genuinely correct # when fetched, just not anymore now that the date has turned over. if self.checked_date != date.today(): return True return (time.time() - self.checked_at) >= poll_interval class Scheduler: def __init__(self, config, screens: dict, display): self.config = config self.screens = screens self.display = display self._caches = {screen_id: ScreenCache() for screen_id in screens} self._rotation_index = 0 self._rotation_switched_at = time.time() self._last_image_hash: str | None = None self._force_once = False self._wake = threading.Event() self._running = False self._thread: threading.Thread | None = None self._status_lock = threading.Lock() self._status = {"current_screen": None, "last_render_at": None, "last_display_write_at": None} # -------------------------------------------------------------- public def start(self): if self._thread and self._thread.is_alive(): return self._running = True self._thread = threading.Thread(target=self._run, daemon=True) self._thread.start() logger.info("Scheduler started") def stop(self): self._running = False self._wake.set() if self._thread: self._thread.join() def request_manual_refresh(self): self._force_once = True self._wake.set() def request_switch(self, screen_id: str): """Pin a screen indefinitely (persisted in config, turns rotation off). Navidrome priority can still preempt it if something starts playing -- that's the one thing this app promises to always show reliably -- but rotation won't, until it's explicitly re-enabled.""" self.config.pin_screen(screen_id) self._wake.set() def request_resume_rotation(self): self.config.resume_rotation() self._wake.set() def invalidate_screen(self, screen_id: str): """Force the next tick to re-check() this screen instead of reusing its cached state, however much of its poll_interval is left. Without this, a settings change (e.g. weather's forecast_days) sits in config.json immediately but the screen keeps rendering whatever it last fetched under the *old* settings until its own poll_interval happens to elapse -- up to 30 minutes for weather's default.""" cache = self._caches.get(screen_id) if cache is not None: cache.checked_at = 0.0 self._wake.set() def get_status(self) -> dict: with self._status_lock: status = dict(self._status) rotation = self.config.get_rotation() pinned = self.config.get_pinned_screen() status["pinned_screen"] = pinned if (pinned and not rotation.get("enabled", True)) else None return status # ------------------------------------------------------------- internal def _run(self): while self._running: try: self._tick() except Exception: logger.exception("Scheduler tick failed") self._wake.wait(timeout=TICK_SECONDS) self._wake.clear() def _tick(self): screen_id, state, did_check = self._select_screen() screen = self.screens[screen_id] settings = self.config.get_screen_settings(screen_id) resolution = self.display.resolution image = screen.render(state, settings, resolution) image_hash = hashlib.sha256(image.tobytes()).hexdigest() self._save_preview(image) with self._status_lock: self._status["current_screen"] = screen_id self._status["last_render_at"] = time.time() if image_hash != self._last_image_hash or self._force_once: logger.info("Content changed (or forced) -- writing to display. screen=%s", screen_id) self.display.show(image) self.display.sleep() self._last_image_hash = image_hash self._force_once = False with self._status_lock: self._status["last_display_write_at"] = time.time() else: logger.debug("No change for screen=%s, skipping display write", screen_id) if did_check: self.config.save() def _select_screen(self) -> tuple[str, object, bool]: """Returns (screen_id, state, did_check_happen). Priority order: Navidrome-when-playing (if enabled) always wins -- that's the one thing this app promises to show reliably. Then a manual "show this now" pin, if rotation is off because of one (set together in Config.pin_screen()). Then normal rotation. """ if self.config.get_navidrome_priority() and "navidrome" in self.screens: screen_id, state, checked = self._poll_screen("navidrome") if state is not None: return screen_id, state, checked rotation = self.config.get_rotation() if not rotation.get("enabled", True): pinned = self.config.get_pinned_screen() if pinned and pinned in self.screens: return self._poll_screen(pinned) return self._rotation_screen() def _rotation_screen(self) -> tuple[str, object, bool]: rotation = self.config.get_rotation() screen_ids = [s for s in rotation["screens"] if s in self.screens] if not screen_ids: # Nothing configured to rotate through -- fall back to whatever # exists so we're never stuck showing nothing. screen_ids = list(self.screens.keys()) now = time.time() # With rotation disabled, just pin to whatever's currently selected -- # never auto-advance. if rotation.get("enabled", True): interval_seconds = rotation["interval_minutes"] * 60 if now - self._rotation_switched_at >= interval_seconds: self._rotation_index = (self._rotation_index + 1) % len(screen_ids) self._rotation_switched_at = now screen_id = screen_ids[self._rotation_index % len(screen_ids)] return self._poll_screen(screen_id) def _poll_screen(self, screen_id: str) -> tuple[str, object, bool]: cache = self._caches[screen_id] screen = self.screens[screen_id] settings = self.config.get_screen_settings(screen_id) checked = False if cache.is_stale(screen.get_poll_interval(settings)): cache.state = self._check(screen_id) cache.checked_at = time.time() cache.checked_date = date.today() checked = True return screen_id, cache.state, checked def _check(self, screen_id: str): screen = self.screens[screen_id] settings = self.config.get_screen_settings(screen_id) try: return screen.check(settings) except Exception: logger.exception("check() failed for screen=%s", screen_id) return None def _save_preview(self, image: Image.Image): try: PREVIEW_PATH.parent.mkdir(parents=True, exist_ok=True) image.save(PREVIEW_PATH) except OSError: logger.exception("Could not write preview image")