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Add native PPF pixel font rendering to simulator #92

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71 changes: 66 additions & 5 deletions simulator/badge_simulator.py
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@
import json
import math
import os
import struct
import sys
import traceback
from types import ModuleType
Expand Down Expand Up @@ -587,6 +588,64 @@ def xor(r, g=None, b=None, a=255) -> tuple:
return brushes.color(r, g, b, a)


class _PPFFont:
"""Native PPF pixel font renderer."""
def __init__(self, path):
with open(path, "rb") as f:
self._data = f.read()
self._glyph_count = struct.unpack_from(">I", self._data, 6)[0]
self._bbox_w = struct.unpack_from(">H", self._data, 10)[0]
self._bbox_h = struct.unpack_from(">H", self._data, 12)[0]
self._row_bytes = (self._bbox_w + 7) // 8
self._glyph_data_size = self._row_bytes * self._bbox_h
self._table_start = 46
self._bitmap_start = self._table_start + self._glyph_count * 6
self._glyphs = {}
for i in range(self._glyph_count):
off = self._table_start + i * 6
cp = struct.unpack_from(">I", self._data, off)[0]
w = struct.unpack_from(">H", self._data, off + 4)[0]
Comment on lines +596 to +607

Copilot AI Mar 31, 2026

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_PPFFont.init parses fixed offsets (glyph_count/bbox/table_start) without validating the file signature or ensuring the computed table/bitmap ranges are within the file length. If a .ppf is truncated/corrupted, it may initialize successfully but later crash in render() with IndexError. Consider validating the magic (e.g., b"ppf!") and bounds-checking (len(_data) >= bitmap_start + glyph_count * glyph_data_size) and raising a clear exception so PixelFont.load() can safely fall back.

Suggested change
self._glyph_count = struct.unpack_from(">I", self._data, 6)[0]
self._bbox_w = struct.unpack_from(">H", self._data, 10)[0]
self._bbox_h = struct.unpack_from(">H", self._data, 12)[0]
self._row_bytes = (self._bbox_w + 7) // 8
self._glyph_data_size = self._row_bytes * self._bbox_h
self._table_start = 46
self._bitmap_start = self._table_start + self._glyph_count * 6
self._glyphs = {}
for i in range(self._glyph_count):
off = self._table_start + i * 6
cp = struct.unpack_from(">I", self._data, off)[0]
w = struct.unpack_from(">H", self._data, off + 4)[0]
data = self._data
data_len = len(data)
# Basic sanity checks: header size and magic signature.
# The PPF format used here is expected to start with b"ppf!".
if data_len < 16:
raise ValueError("PPF font file too short: %r" % (path,))
if data[:4] != b"ppf!":
raise ValueError("Invalid PPF font signature in %r" % (path,))
# Parse header values from fixed offsets.
self._glyph_count = struct.unpack_from(">I", data, 6)[0]
self._bbox_w = struct.unpack_from(">H", data, 10)[0]
self._bbox_h = struct.unpack_from(">H", data, 12)[0]
# Sanity-check bounding box dimensions.
if self._bbox_w <= 0 or self._bbox_h <= 0:
raise ValueError("Invalid PPF font metrics in %r" % (path,))
self._row_bytes = (self._bbox_w + 7) // 8
self._glyph_data_size = self._row_bytes * self._bbox_h
self._table_start = 46
self._bitmap_start = self._table_start + self._glyph_count * 6
# Ensure glyph table and bitmap data both fit within the file.
glyph_table_end = self._table_start + self._glyph_count * 6
if glyph_table_end > data_len:
raise ValueError("Corrupt PPF font (truncated glyph table): %r" % (path,))
bitmap_end = self._bitmap_start + self._glyph_count * self._glyph_data_size
if bitmap_end > data_len:
raise ValueError("Corrupt PPF font (truncated bitmap data): %r" % (path,))
self._glyphs = {}
for i in range(self._glyph_count):
off = self._table_start + i * 6
cp = struct.unpack_from(">I", data, off)[0]
w = struct.unpack_from(">H", data, off + 4)[0]

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self._glyphs[cp] = (i, w)

def get_height(self):
return self._bbox_h

def size(self, text):
text = str(text)
w = 0
space_w = self._bbox_w // 3
for ch in text:
cp = ord(ch)
if cp == 32:
w += space_w + 1
elif cp in self._glyphs:
w += self._glyphs[cp][1] + 1
return (max(0, w - 1), self._bbox_h)
Comment on lines +615 to +623

Copilot AI Mar 31, 2026

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Space width is hard-coded as bbox_w // 3, even though PPF fonts commonly include an explicit glyph-table entry for U+0020 (space). This can make spacing differ from the actual font metrics. Prefer using the glyph-table width for codepoint 32 when present (and only fall back to bbox_w // 3 when it is not).

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def render(self, text, antialias, color, *args, **kwargs):
text = str(text)
tw, th = self.size(text)
surf = pygame.Surface((max(1, tw), th), pygame.SRCALPHA)

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render() guards against zero-width surfaces via max(1, tw) but not zero height; if bbox_h is ever 0 (bad/corrupt font) pygame.Surface((..., 0)) will raise. Consider using max(1, th) as well (and/or validating bbox_h > 0 during init).

Suggested change
surf = pygame.Surface((max(1, tw), th), pygame.SRCALPHA)
surf = pygame.Surface((max(1, tw), max(1, th)), pygame.SRCALPHA)

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space_w = self._bbox_w // 3
x = 0
for ch in text:
cp = ord(ch)
if cp == 32:
x += space_w + 1
continue
if cp not in self._glyphs:
continue
Comment on lines +617 to +637

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For characters not present in the glyph table, both size() and render() currently skip without advancing x/w. That causes subsequent glyphs to overlap and size() to under-report width for strings containing unknown codepoints. Consider advancing by a fallback width (e.g., space width or bbox_w) and/or rendering a replacement glyph (like '?') to preserve layout.

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idx, gw = self._glyphs[cp]
bmp_off = self._bitmap_start + idx * self._glyph_data_size
for row in range(self._bbox_h):
for col in range(gw):
byte_idx = bmp_off + row * self._row_bytes + (col >> 3)
if self._data[byte_idx] & (1 << (7 - (col & 7))):
surf.set_at((x + col, row), color)
x += gw + 1
Comment on lines +625 to +645

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_PPFFont.render() uses nested loops with surf.set_at() per pixel; in pygame this is very slow and can become a bottleneck when drawing lots of text each frame. At minimum, lock the surface during pixel writes (surf.lock()/unlock()), or switch to a faster bulk approach (PixelArray/surfarray) to keep simulator FPS stable.

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return surf


class PixelFont:
class _Wrapper:
__slots__ = ("_font", "name", "height")
Expand Down Expand Up @@ -615,15 +674,17 @@ def load(path: str, size: int = 14):
font = None
if os.path.exists(resolved):
ext = os.path.splitext(resolved)[1].lower()
if ext in {".ttf", ".otf", ".ttc"}:
if ext == ".ppf":
try:
font = _PPFFont(resolved)
except Exception as e:
print(f"PPF load failed for {resolved}: {e}")
font = None
elif ext in {".ttf", ".otf", ".ttc"}:
try:
font = pygame.font.Font(resolved, size)
except Exception:
font = None
else:
# Pico pixel fonts (`.ppf`) aren't true TTF files; using the
# default pygame font keeps the simulator stable.
font = None
if font is None:
font = pygame.font.Font(None, size)

Expand Down
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