Source code for PIL.PcfFontFile

#
# THIS IS WORK IN PROGRESS
#
# The Python Imaging Library
# $Id$
#
# portable compiled font file parser
#
# history:
# 1997-08-19 fl   created
# 2003-09-13 fl   fixed loading of unicode fonts
#
# Copyright (c) 1997-2003 by Secret Labs AB.
# Copyright (c) 1997-2003 by Fredrik Lundh.
#
# See the README file for information on usage and redistribution.
#
from __future__ import annotations

import io
from typing import BinaryIO, Callable

from . import FontFile, Image
from ._binary import i8
from ._binary import i16be as b16
from ._binary import i16le as l16
from ._binary import i32be as b32
from ._binary import i32le as l32

# --------------------------------------------------------------------
# declarations

PCF_MAGIC = 0x70636601  # "\x01fcp"

PCF_PROPERTIES = 1 << 0
PCF_ACCELERATORS = 1 << 1
PCF_METRICS = 1 << 2
PCF_BITMAPS = 1 << 3
PCF_INK_METRICS = 1 << 4
PCF_BDF_ENCODINGS = 1 << 5
PCF_SWIDTHS = 1 << 6
PCF_GLYPH_NAMES = 1 << 7
PCF_BDF_ACCELERATORS = 1 << 8

BYTES_PER_ROW: list[Callable[[int], int]] = [
    lambda bits: ((bits + 7) >> 3),
    lambda bits: ((bits + 15) >> 3) & ~1,
    lambda bits: ((bits + 31) >> 3) & ~3,
    lambda bits: ((bits + 63) >> 3) & ~7,
]


[docs] def sz(s: bytes, o: int) -> bytes: return s[o : s.index(b"\0", o)]
[docs] class PcfFontFile(FontFile.FontFile): """Font file plugin for the X11 PCF format.""" name = "name" def __init__(self, fp: BinaryIO, charset_encoding: str = "iso8859-1"): self.charset_encoding = charset_encoding magic = l32(fp.read(4)) if magic != PCF_MAGIC: msg = "not a PCF file" raise SyntaxError(msg) super().__init__() count = l32(fp.read(4)) self.toc = {} for i in range(count): type = l32(fp.read(4)) self.toc[type] = l32(fp.read(4)), l32(fp.read(4)), l32(fp.read(4)) self.fp = fp self.info = self._load_properties() metrics = self._load_metrics() bitmaps = self._load_bitmaps(metrics) encoding = self._load_encoding() # # create glyph structure for ch, ix in enumerate(encoding): if ix is not None: ( xsize, ysize, left, right, width, ascent, descent, attributes, ) = metrics[ix] self.glyph[ch] = ( (width, 0), (left, descent - ysize, xsize + left, descent), (0, 0, xsize, ysize), bitmaps[ix], ) def _getformat( self, tag: int ) -> tuple[BinaryIO, int, Callable[[bytes], int], Callable[[bytes], int]]: format, size, offset = self.toc[tag] fp = self.fp fp.seek(offset) format = l32(fp.read(4)) if format & 4: i16, i32 = b16, b32 else: i16, i32 = l16, l32 return fp, format, i16, i32 def _load_properties(self) -> dict[bytes, bytes | int]: # # font properties properties = {} fp, format, i16, i32 = self._getformat(PCF_PROPERTIES) nprops = i32(fp.read(4)) # read property description p = [(i32(fp.read(4)), i8(fp.read(1)), i32(fp.read(4))) for _ in range(nprops)] if nprops & 3: fp.seek(4 - (nprops & 3), io.SEEK_CUR) # pad data = fp.read(i32(fp.read(4))) for k, s, v in p: property_value: bytes | int = sz(data, v) if s else v properties[sz(data, k)] = property_value return properties def _load_metrics(self) -> list[tuple[int, int, int, int, int, int, int, int]]: # # font metrics metrics: list[tuple[int, int, int, int, int, int, int, int]] = [] fp, format, i16, i32 = self._getformat(PCF_METRICS) append = metrics.append if (format & 0xFF00) == 0x100: # "compressed" metrics for i in range(i16(fp.read(2))): left = i8(fp.read(1)) - 128 right = i8(fp.read(1)) - 128 width = i8(fp.read(1)) - 128 ascent = i8(fp.read(1)) - 128 descent = i8(fp.read(1)) - 128 xsize = right - left ysize = ascent + descent append((xsize, ysize, left, right, width, ascent, descent, 0)) else: # "jumbo" metrics for i in range(i32(fp.read(4))): left = i16(fp.read(2)) right = i16(fp.read(2)) width = i16(fp.read(2)) ascent = i16(fp.read(2)) descent = i16(fp.read(2)) attributes = i16(fp.read(2)) xsize = right - left ysize = ascent + descent append((xsize, ysize, left, right, width, ascent, descent, attributes)) return metrics def _load_bitmaps( self, metrics: list[tuple[int, int, int, int, int, int, int, int]] ) -> list[Image.Image]: # # bitmap data fp, format, i16, i32 = self._getformat(PCF_BITMAPS) nbitmaps = i32(fp.read(4)) if nbitmaps != len(metrics): msg = "Wrong number of bitmaps" raise OSError(msg) offsets = [i32(fp.read(4)) for _ in range(nbitmaps)] bitmap_sizes = [i32(fp.read(4)) for _ in range(4)] # byteorder = format & 4 # non-zero => MSB bitorder = format & 8 # non-zero => MSB padindex = format & 3 bitmapsize = bitmap_sizes[padindex] offsets.append(bitmapsize) data = fp.read(bitmapsize) pad = BYTES_PER_ROW[padindex] mode = "1;R" if bitorder: mode = "1" bitmaps = [] for i in range(nbitmaps): xsize, ysize = metrics[i][:2] b, e = offsets[i : i + 2] bitmaps.append( Image.frombytes("1", (xsize, ysize), data[b:e], "raw", mode, pad(xsize)) ) return bitmaps def _load_encoding(self) -> list[int | None]: fp, format, i16, i32 = self._getformat(PCF_BDF_ENCODINGS) first_col, last_col = i16(fp.read(2)), i16(fp.read(2)) first_row, last_row = i16(fp.read(2)), i16(fp.read(2)) i16(fp.read(2)) # default nencoding = (last_col - first_col + 1) * (last_row - first_row + 1) # map character code to bitmap index encoding: list[int | None] = [None] * min(256, nencoding) encoding_offsets = [i16(fp.read(2)) for _ in range(nencoding)] for i in range(first_col, len(encoding)): try: encoding_offset = encoding_offsets[ ord(bytearray([i]).decode(self.charset_encoding)) ] if encoding_offset != 0xFFFF: encoding[i] = encoding_offset except UnicodeDecodeError: # character is not supported in selected encoding pass return encoding