Initial commit: Paperwall, a standalone e-ink dashboard

Navidrome now-playing, clock, and weather for a Waveshare epd4in0e panel,
with a local web UI and install/uninstall scripts for the Pi.

display/epd4in0e_driver.py

@@ -0,0 +1,54 @@
+"""Driver for the Waveshare epd4in0e (4", 6-color Spectra) panel.
+
+Thin wrapper around the vendored `waveshare_epd.epd4in0e` module -- the exact
+driver already proven working under the InkyPi install on this Pi. That
+driver only exposes `Clear()` and `display()`, both of which do a full
+`TurnOnDisplay()` flash cycle; there is no partial-refresh path for this
+panel at the hardware/SDK level, confirmed by reading the driver itself.
+"""
+
+import logging
+
+from display import Display
+
+logger = logging.getLogger(__name__)
+
+RESOLUTION = (400, 600)
+
+
+class EPD4in0eDisplay(Display):
+    def __init__(self):
+        self.resolution = RESOLUTION
+        self._epd = None
+
+    def init(self) -> None:
+        from waveshare_epd import epd4in0e
+
+        self._epd = epd4in0e.EPD()
+        self._epd.init()
+        logger.info("epd4in0e initialized")
+
+    def show(self, image) -> None:
+        if self._epd is None:
+            self.init()
+
+        width, height = self.resolution
+        if image.size != (width, height):
+            raise ValueError(
+                f"Image size {image.size} does not match panel resolution {self.resolution}"
+            )
+
+        # Re-init: the panel goes to sleep after every show(), and needs a
+        # fresh init() before it will accept commands again.
+        self._epd.init()
+
+        # Clear first to avoid ghosting from the previous image -- also a
+        # full flash, there's no way around it on this panel.
+        self._epd.Clear()
+
+        self._epd.display(self._epd.getbuffer(image.convert("RGB")))
+
+    def sleep(self) -> None:
+        if self._epd is not None:
+            self._epd.sleep()
+        logger.info("epd4in0e put to sleep")