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.
#

import io

from . import FontFile, Image
from ._binary import i8, i16be as b16, i16le as l16, i32be as b32, 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 = [
    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, o): return s[o : s.index(b"\0", o)]
## # Font file plugin for the X11 PCF format.
[docs]class PcfFontFile(FontFile.FontFile): name = "name" def __init__(self, fp): magic = l32(fp.read(4)) if magic != PCF_MAGIC: raise SyntaxError("not a PCF file") 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 in range(256): ix = encoding[ch] if ix is not None: x, y, l, r, w, a, d, f = metrics[ix] glyph = (w, 0), (l, d - y, x + l, d), (0, 0, x, y), bitmaps[ix] self.glyph[ch] = glyph def _getformat(self, tag): 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): # # font properties properties = {} fp, format, i16, i32 = self._getformat(PCF_PROPERTIES) nprops = i32(fp.read(4)) # read property description p = [] for i in range(nprops): p.append((i32(fp.read(4)), i8(fp.read(1)), i32(fp.read(4)))) 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: k = sz(data, k) if s: v = sz(data, v) properties[k] = v return properties def _load_metrics(self): # # font metrics metrics = [] 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): # # bitmap data bitmaps = [] fp, format, i16, i32 = self._getformat(PCF_BITMAPS) nbitmaps = i32(fp.read(4)) if nbitmaps != len(metrics): raise OSError("Wrong number of bitmaps") offsets = [] for i in range(nbitmaps): offsets.append(i32(fp.read(4))) bitmapSizes = [] for i in range(4): bitmapSizes.append(i32(fp.read(4))) # byteorder = format & 4 # non-zero => MSB bitorder = format & 8 # non-zero => MSB padindex = format & 3 bitmapsize = bitmapSizes[padindex] offsets.append(bitmapsize) data = fp.read(bitmapsize) pad = BYTES_PER_ROW[padindex] mode = "1;R" if bitorder: mode = "1" for i in range(nbitmaps): x, y, l, r, w, a, d, f = metrics[i] b, e = offsets[i], offsets[i + 1] bitmaps.append(Image.frombytes("1", (x, y), data[b:e], "raw", mode, pad(x))) return bitmaps def _load_encoding(self): # map character code to bitmap index encoding = [None] * 256 fp, format, i16, i32 = self._getformat(PCF_BDF_ENCODINGS) firstCol, lastCol = i16(fp.read(2)), i16(fp.read(2)) firstRow, lastRow = i16(fp.read(2)), i16(fp.read(2)) i16(fp.read(2)) # default nencoding = (lastCol - firstCol + 1) * (lastRow - firstRow + 1) for i in range(nencoding): encodingOffset = i16(fp.read(2)) if encodingOffset != 0xFFFF: try: encoding[i + firstCol] = encodingOffset except IndexError: break # only load ISO-8859-1 glyphs return encoding