Viewing file:  PcfFontFile.py (6.2 KB) -rw-r--r--
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#
# 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
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 = [
lambda bits: ((bits + 7) >> 3),
lambda bits: ((bits + 15) >> 3) & ~1,
lambda bits: ((bits + 31) >> 3) & ~3,
lambda bits: ((bits + 63) >> 3) & ~7,
]
def sz(s, o):
return s[o : s.index(b"\0", o)]
class PcfFontFile(FontFile.FontFile):
"""Font file plugin for the X11 PCF format."""
name = "name"
def __init__(self, fp, charset_encoding="iso8859-1"):
self.charset_encoding = charset_encoding
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)
encodingOffsets = [i16(fp.read(2)) for _ in range(nencoding)]
for i in range(firstCol, len(encoding)):
try:
encodingOffset = encodingOffsets[
ord(bytearray([i]).decode(self.charset_encoding))
]
if encodingOffset != 0xFFFF:
encoding[i] = encodingOffset
except UnicodeDecodeError:
# character is not supported in selected encoding
pass
return encoding
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