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.

screens/render_utils.py

@@ -0,0 +1,79 @@
+"""Shared PIL rendering helpers: font loading and text layout.
+
+The panel driver dithers whatever RGB image we hand it down to its 6-color
+palette (see epd4in0e.getbuffer, which quantizes with Floyd-Steinberg
+dithering by default) -- so screens can draw with normal anti-aliased RGB
+text and full-color cover art without worrying about the palette themselves.
+"""
+
+from pathlib import Path
+
+from PIL import ImageFont
+
+FONTS_DIR = Path(__file__).resolve().parent.parent / "fonts"
+
+_font_cache: dict[tuple[str, int], ImageFont.FreeTypeFont] = {}
+
+
+def load_font(size: int, bold: bool = False) -> ImageFont.FreeTypeFont:
+    key = ("bold" if bold else "regular", size)
+    if key not in _font_cache:
+        filename = "DejaVuSans-Bold.ttf" if bold else "DejaVuSans.ttf"
+        _font_cache[key] = ImageFont.truetype(str(FONTS_DIR / filename), size)
+    return _font_cache[key]
+
+
+def text_width(draw, text: str, font: ImageFont.FreeTypeFont) -> int:
+    left, _, right, _ = draw.textbbox((0, 0), text, font=font)
+    return right - left
+
+
+def truncate_to_width(draw, text: str, font: ImageFont.FreeTypeFont, max_width: int) -> str:
+    """Single-line ellipsis truncation, mirroring the CSS text-overflow: ellipsis look."""
+    if text_width(draw, text, font) <= max_width:
+        return text
+
+    ellipsis = "…"
+    lo, hi = 0, len(text)
+    while lo < hi:
+        mid = (lo + hi + 1) // 2
+        candidate = text[:mid].rstrip() + ellipsis
+        if text_width(draw, candidate, font) <= max_width:
+            lo = mid
+        else:
+            hi = mid - 1
+    return text[:lo].rstrip() + ellipsis if lo else ellipsis
+
+
+def wrap_to_lines(draw, text: str, font: ImageFont.FreeTypeFont, max_width: int, max_lines: int) -> list[str]:
+    """Word-wrap up to `max_lines`, ellipsis-truncating the last line if it still
+    overflows -- mirrors the CSS -webkit-line-clamp behavior used in the old design."""
+    words = text.split()
+    if not words:
+        return []
+
+    lines: list[str] = []
+    current = words[0]
+    next_index = 1
+    while next_index < len(words):
+        word = words[next_index]
+        candidate = f"{current} {word}"
+        if text_width(draw, candidate, font) <= max_width:
+            current = candidate
+            next_index += 1
+            continue
+
+        lines.append(current)
+        current = word
+        next_index += 1
+        if len(lines) == max_lines - 1:
+            break
+
+    if next_index < len(words):
+        # Ran out of lines with words still remaining -- fold the rest into
+        # the last line and ellipsis-truncate it.
+        current = current + " " + " ".join(words[next_index:])
+        current = truncate_to_width(draw, current, font, max_width)
+
+    lines.append(current)
+    return lines[:max_lines]