255 lines
7.0 KiB
Python
255 lines
7.0 KiB
Python
#
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# THIS IS WORK IN PROGRESS
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#
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# The Python Imaging Library
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# $Id$
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#
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# portable compiled font file parser
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#
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# history:
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# 1997-08-19 fl created
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# 2003-09-13 fl fixed loading of unicode fonts
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#
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# Copyright (c) 1997-2003 by Secret Labs AB.
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# Copyright (c) 1997-2003 by Fredrik Lundh.
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#
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# See the README file for information on usage and redistribution.
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#
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from __future__ import annotations
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import io
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from typing import BinaryIO, Callable
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from . import FontFile, Image
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from ._binary import i8
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from ._binary import i16be as b16
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from ._binary import i16le as l16
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from ._binary import i32be as b32
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from ._binary import i32le as l32
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# --------------------------------------------------------------------
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# declarations
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PCF_MAGIC = 0x70636601 # "\x01fcp"
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PCF_PROPERTIES = 1 << 0
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PCF_ACCELERATORS = 1 << 1
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PCF_METRICS = 1 << 2
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PCF_BITMAPS = 1 << 3
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PCF_INK_METRICS = 1 << 4
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PCF_BDF_ENCODINGS = 1 << 5
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PCF_SWIDTHS = 1 << 6
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PCF_GLYPH_NAMES = 1 << 7
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PCF_BDF_ACCELERATORS = 1 << 8
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BYTES_PER_ROW: list[Callable[[int], int]] = [
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lambda bits: ((bits + 7) >> 3),
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lambda bits: ((bits + 15) >> 3) & ~1,
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lambda bits: ((bits + 31) >> 3) & ~3,
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lambda bits: ((bits + 63) >> 3) & ~7,
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]
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def sz(s: bytes, o: int) -> bytes:
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return s[o : s.index(b"\0", o)]
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class PcfFontFile(FontFile.FontFile):
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"""Font file plugin for the X11 PCF format."""
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name = "name"
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def __init__(self, fp: BinaryIO, charset_encoding: str = "iso8859-1"):
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self.charset_encoding = charset_encoding
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magic = l32(fp.read(4))
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if magic != PCF_MAGIC:
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msg = "not a PCF file"
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raise SyntaxError(msg)
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super().__init__()
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count = l32(fp.read(4))
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self.toc = {}
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for i in range(count):
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type = l32(fp.read(4))
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self.toc[type] = l32(fp.read(4)), l32(fp.read(4)), l32(fp.read(4))
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self.fp = fp
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self.info = self._load_properties()
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metrics = self._load_metrics()
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bitmaps = self._load_bitmaps(metrics)
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encoding = self._load_encoding()
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#
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# create glyph structure
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for ch, ix in enumerate(encoding):
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if ix is not None:
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(
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xsize,
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ysize,
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left,
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right,
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width,
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ascent,
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descent,
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attributes,
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) = metrics[ix]
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self.glyph[ch] = (
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(width, 0),
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(left, descent - ysize, xsize + left, descent),
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(0, 0, xsize, ysize),
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bitmaps[ix],
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)
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def _getformat(
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self, tag: int
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) -> tuple[BinaryIO, int, Callable[[bytes], int], Callable[[bytes], int]]:
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format, size, offset = self.toc[tag]
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fp = self.fp
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fp.seek(offset)
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format = l32(fp.read(4))
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if format & 4:
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i16, i32 = b16, b32
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else:
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i16, i32 = l16, l32
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return fp, format, i16, i32
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def _load_properties(self) -> dict[bytes, bytes | int]:
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#
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# font properties
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properties = {}
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fp, format, i16, i32 = self._getformat(PCF_PROPERTIES)
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nprops = i32(fp.read(4))
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# read property description
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p = [(i32(fp.read(4)), i8(fp.read(1)), i32(fp.read(4))) for _ in range(nprops)]
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if nprops & 3:
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fp.seek(4 - (nprops & 3), io.SEEK_CUR) # pad
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data = fp.read(i32(fp.read(4)))
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for k, s, v in p:
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property_value: bytes | int = sz(data, v) if s else v
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properties[sz(data, k)] = property_value
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return properties
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def _load_metrics(self) -> list[tuple[int, int, int, int, int, int, int, int]]:
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#
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# font metrics
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metrics: list[tuple[int, int, int, int, int, int, int, int]] = []
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fp, format, i16, i32 = self._getformat(PCF_METRICS)
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append = metrics.append
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if (format & 0xFF00) == 0x100:
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# "compressed" metrics
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for i in range(i16(fp.read(2))):
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left = i8(fp.read(1)) - 128
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right = i8(fp.read(1)) - 128
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width = i8(fp.read(1)) - 128
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ascent = i8(fp.read(1)) - 128
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descent = i8(fp.read(1)) - 128
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xsize = right - left
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ysize = ascent + descent
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append((xsize, ysize, left, right, width, ascent, descent, 0))
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else:
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# "jumbo" metrics
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for i in range(i32(fp.read(4))):
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left = i16(fp.read(2))
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right = i16(fp.read(2))
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width = i16(fp.read(2))
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ascent = i16(fp.read(2))
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descent = i16(fp.read(2))
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attributes = i16(fp.read(2))
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xsize = right - left
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ysize = ascent + descent
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append((xsize, ysize, left, right, width, ascent, descent, attributes))
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return metrics
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def _load_bitmaps(
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self, metrics: list[tuple[int, int, int, int, int, int, int, int]]
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) -> list[Image.Image]:
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#
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# bitmap data
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fp, format, i16, i32 = self._getformat(PCF_BITMAPS)
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nbitmaps = i32(fp.read(4))
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if nbitmaps != len(metrics):
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msg = "Wrong number of bitmaps"
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raise OSError(msg)
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offsets = [i32(fp.read(4)) for _ in range(nbitmaps)]
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bitmap_sizes = [i32(fp.read(4)) for _ in range(4)]
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# byteorder = format & 4 # non-zero => MSB
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bitorder = format & 8 # non-zero => MSB
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padindex = format & 3
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bitmapsize = bitmap_sizes[padindex]
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offsets.append(bitmapsize)
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data = fp.read(bitmapsize)
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pad = BYTES_PER_ROW[padindex]
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mode = "1;R"
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if bitorder:
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mode = "1"
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bitmaps = []
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for i in range(nbitmaps):
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xsize, ysize = metrics[i][:2]
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b, e = offsets[i : i + 2]
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bitmaps.append(
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Image.frombytes("1", (xsize, ysize), data[b:e], "raw", mode, pad(xsize))
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)
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return bitmaps
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def _load_encoding(self) -> list[int | None]:
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fp, format, i16, i32 = self._getformat(PCF_BDF_ENCODINGS)
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first_col, last_col = i16(fp.read(2)), i16(fp.read(2))
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first_row, last_row = i16(fp.read(2)), i16(fp.read(2))
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i16(fp.read(2)) # default
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nencoding = (last_col - first_col + 1) * (last_row - first_row + 1)
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# map character code to bitmap index
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encoding: list[int | None] = [None] * min(256, nencoding)
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encoding_offsets = [i16(fp.read(2)) for _ in range(nencoding)]
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for i in range(first_col, len(encoding)):
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try:
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encoding_offset = encoding_offsets[
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ord(bytearray([i]).decode(self.charset_encoding))
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]
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if encoding_offset != 0xFFFF:
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encoding[i] = encoding_offset
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except UnicodeDecodeError:
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# character is not supported in selected encoding
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pass
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return encoding
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