"""

A module for reading dvi files output by TeX. Several limitations make

this not (currently) useful as a general-purpose dvi preprocessor, but

it is currently used by the pdf backend for processing usetex text.

Interface::

with Dvi(filename, 72) as dvi:

# iterate over pages:

for page in dvi:

w, h, d = page.width, page.height, page.descent

for x, y, font, glyph, width in page.text:

fontname = font.texname

pointsize = font.size

...

for x, y, height, width in page.boxes:

...

"""

import dataclasses

import enum

import logging

import os

import re

import struct

import subprocess

import sys

from collections import namedtuple

from functools import cache, cached_property, lru_cache, partial, wraps

from pathlib import Path

import fontTools.agl

import numpy as np

import matplotlib as mpl

from matplotlib import _api, cbook, font_manager

from matplotlib.ft2font import LoadFlags

_log = logging.getLogger(__name__)

# Many dvi related files are looked for by external processes, require

# additional parsing, and are used many times per rendering, which is why they

# are cached using lru_cache().

# Dvi is a bytecode format documented in

# https://ctan.org/pkg/dvitype

# https://texdoc.org/serve/dvitype.pdf/0

#

# The file consists of a preamble, some number of pages, a postamble,

# and a finale. Different opcodes are allowed in different contexts,

# so the Dvi object has a parser state:

#

# pre: expecting the preamble

# outer: between pages (followed by a page or the postamble,

# also e.g. font definitions are allowed)

# page: processing a page

# post_post: state after the postamble (our current implementation

# just stops reading)

# finale: the finale (unimplemented in our current implementation)

_dvistate = enum.Enum('DviState', 'pre outer inpage post_post finale')

# The marks on a page consist of text and boxes. A page also has dimensions.

Page = namedtuple('Page', 'text boxes height width descent')

Box = namedtuple('Box', 'x y height width')

# Also a namedtuple, for backcompat.

class Text(namedtuple('Text', 'x y font glyph width')):

"""

A glyph in the dvi file.

In order to render the glyph, load the glyph at index ``text.index``

from the font at ``text.font.resolve_path()`` with size ``text.font.size``,

warped with ``text.font.effects``, then draw it at position

``(text.x, text.y)``.

``text.glyph`` is the glyph number actually stored in the dvi file (whose

interpretation depends on the font). ``text.width`` is the glyph width in

dvi units.

"""

@property

def index(self):

"""

The FreeType index of this glyph (that can be passed to FT_Load_Glyph).

"""

# See DviFont._index_dvi_to_freetype for details on the index mapping.

return self.font._index_dvi_to_freetype(self.glyph)

font_path = property(lambda self: self.font.resolve_path())

font_size = property(lambda self: self.font.size)

font_effects = property(lambda self: self.font.effects)

@property # To be deprecated together with font_path, font_size, font_effects.

def glyph_name_or_index(self):

"""

The glyph name, the native charmap glyph index, or the raw glyph index.

If the font is a TrueType file (which can currently only happen for

DVI files generated by xetex or luatex), then this number is the raw

index of the glyph, which can be passed to FT_Load_Glyph/load_glyph.

Otherwise, the font is a PostScript font. For such fonts, if

:file:`pdftex.map` specifies an encoding for this glyph's font,

that is a mapping of glyph indices to Adobe glyph names; which

is used by this property to convert dvi numbers to glyph names.

Callers can then convert glyph names to glyph indices (with

FT_Get_Name_Index/get_name_index), and load the glyph using

FT_Load_Glyph/load_glyph.

If :file:`pdftex.map` specifies no encoding for a PostScript font,

this number is an index to the font's "native" charmap; glyphs should

directly load using FT_Load_Char/load_char after selecting the native

charmap.

"""

# The last section is only true on luatex since luaotfload 3.23; this

# must be checked by the code generated by texmanager. (luaotfload's

# docs states "No one should rely on the mapping between DVI character

# codes and font glyphs [prior to v3.15] unless they tightly

# control all involved versions and are deeply familiar with the

# implementation", but a further mapping bug was fixed in luaotfload

# commit 8f2dca4, first included in v3.23).

entry = self._get_pdftexmap_entry()

return (_parse_enc(entry.encoding)[self.glyph]

if entry.encoding is not None else self.glyph)

def _as_unicode_or_name(self):

if self.font.subfont:

raise NotImplementedError("Indexing TTC fonts is not supported yet")

path = self.font.resolve_path()

if path.name.lower().endswith("pk"):

# PK fonts have no encoding information; report glyphs as ASCII but

# with a "?" to indicate that this is just a guess.

return (f"{chr(self.glyph)}?" if chr(self.glyph).isprintable() else

f"pk{self.glyph:#02x}")

face = font_manager.get_font(path)

glyph_name = face.get_glyph_name(self.index)

glyph_str = fontTools.agl.toUnicode(glyph_name)

return glyph_str or glyph_name

# Opcode argument parsing

#

# Each of the following functions takes a Dvi object and delta, which is the

# difference between the opcode and the minimum opcode with the same meaning.

# Dvi opcodes often encode the number of argument bytes in this delta.

_arg_mapping = dict(

# raw: Return delta as is.

raw=lambda dvi, delta: delta,

# u1: Read 1 byte as an unsigned number.

u1=lambda dvi, delta: dvi._read_arg(1, signed=False),

# u4: Read 4 bytes as an unsigned number.

u4=lambda dvi, delta: dvi._read_arg(4, signed=False),

# s4: Read 4 bytes as a signed number.

s4=lambda dvi, delta: dvi._read_arg(4, signed=True),

# slen: Read delta bytes as a signed number, or None if delta is None.

slen=lambda dvi, delta: dvi._read_arg(delta, signed=True) if delta else None,

# slen1: Read (delta + 1) bytes as a signed number.

slen1=lambda dvi, delta: dvi._read_arg(delta + 1, signed=True),

# ulen1: Read (delta + 1) bytes as an unsigned number.

ulen1=lambda dvi, delta: dvi._read_arg(delta + 1, signed=False),

# olen1: Read (delta + 1) bytes as an unsigned number if less than 4 bytes,

# as a signed number if 4 bytes.

olen1=lambda dvi, delta: dvi._read_arg(delta + 1, signed=(delta == 3)),

)

def _dispatch(table, min, max=None, state=None, args=('raw',)):

"""

Decorator for dispatch by opcode. Sets the values in *table*

from *min* to *max* to this method, adds a check that the Dvi state

matches *state* if not None, reads arguments from the file according

to *args*.

Parameters

----------

table : dict[int, callable]

The dispatch table to be filled in.

min, max : int

Range of opcodes that calls the registered function; *max* defaults to

*min*.

state : _dvistate, optional

State of the Dvi object in which these opcodes are allowed.

args : list[str], default: ['raw']

Sequence of argument specifications:

- 'raw': opcode minus minimum

- 'u1': read one unsigned byte

- 'u4': read four bytes, treat as an unsigned number

- 's4': read four bytes, treat as a signed number

- 'slen': read (opcode - minimum) bytes, treat as signed

- 'slen1': read (opcode - minimum + 1) bytes, treat as signed

- 'ulen1': read (opcode - minimum + 1) bytes, treat as unsigned

- 'olen1': read (opcode - minimum + 1) bytes, treat as unsigned

if under four bytes, signed if four bytes

"""

def decorate(method):

get_args = [_arg_mapping[x] for x in args]

@wraps(method)

def wrapper(self, byte):

if state is not None and self.state != state:

raise ValueError("state precondition failed")

return method(self, *[f(self, byte-min) for f in get_args])

if max is None:

table[min] = wrapper

else:

for i in range(min, max+1):

assert table[i] is None

table[i] = wrapper

return wrapper

return decorate

class Dvi:

"""

A reader for a dvi ("device-independent") file, as produced by TeX.

The current implementation can only iterate through pages in order,

and does not even attempt to verify the postamble.

This class can be used as a context manager to close the underlying

file upon exit. Pages can be read via iteration. Here is an overly

simple way to extract text without trying to detect whitespace::

>>> with matplotlib.dviread.Dvi('input.dvi', 72) as dvi:

... for page in dvi:

... print(''.join(chr(t.glyph) for t in page.text))

"""

# dispatch table

_dtable = [None] * 256

_dispatch = partial(_dispatch, _dtable)

def __init__(self, filename, dpi):

"""

Read the data from the file named *filename* and convert

TeX's internal units to units of *dpi* per inch.

*dpi* only sets the units and does not limit the resolution.

Use None to return TeX's internal units.

"""

_log.debug('Dvi: %s', filename)

self.file = open(filename, 'rb')

self.dpi = dpi

self.fonts = {}

self.state = _dvistate.pre

self._missing_font = None

def __enter__(self):

"""Context manager enter method, does nothing."""

return self

def __exit__(self, etype, evalue, etrace):

"""

Context manager exit method, closes the underlying file if it is open.

"""

self.close()

def __iter__(self):

"""

Iterate through the pages of the file.

Yields

------

Page

Details of all the text and box objects on the page.

The Page tuple contains lists of Text and Box tuples and

the page dimensions, and the Text and Box tuples contain

coordinates transformed into a standard Cartesian

coordinate system at the dpi value given when initializing.

The coordinates are floating point numbers, but otherwise

precision is not lost and coordinate values are not clipped to

integers.

"""

while self._read():

yield self._output()

def close(self):

"""Close the underlying file if it is open."""

if not self.file.closed:

self.file.close()

def _output(self):

"""

Output the text and boxes belonging to the most recent page.

page = dvi._output()

"""

minx = miny = np.inf

maxx = maxy = -np.inf

maxy_pure = -np.inf

for elt in self.text + self.boxes:

if isinstance(elt, Box):

x, y, h, w = elt

e = 0 # zero depth

else: # glyph

x, y, font, g, w = elt

h, e = font._height_depth_of(g)

minx = min(minx, x)

miny = min(miny, y - h)

maxx = max(maxx, x + w)

maxy = max(maxy, y + e)

maxy_pure = max(maxy_pure, y)

if self._baseline_v is not None:

maxy_pure = self._baseline_v # This should normally be the case.

self._baseline_v = None

if not self.text and not self.boxes: # Avoid infs/nans from inf+/-inf.

return Page(text=[], boxes=[], width=0, height=0, descent=0)

if self.dpi is None:

# special case for ease of debugging: output raw dvi coordinates

return Page(text=self.text, boxes=self.boxes,

width=maxx-minx, height=maxy_pure-miny,

descent=maxy-maxy_pure)

# convert from TeX's "scaled points" to dpi units

d = self.dpi / (72.27 * 2**16)

descent = (maxy - maxy_pure) * d

text = [Text((x-minx)*d, (maxy-y)*d - descent, f, g, w*d)

for (x, y, f, g, w) in self.text]

boxes = [Box((x-minx)*d, (maxy-y)*d - descent, h*d, w*d)

for (x, y, h, w) in self.boxes]

return Page(text=text, boxes=boxes, width=(maxx-minx)*d,

height=(maxy_pure-miny)*d, descent=descent)

def _read(self):

"""

Read one page from the file. Return True if successful,

False if there were no more pages.

"""

# Pages appear to start with the sequence

# bop (begin of page)

# xxx comment

# <push, ..., pop> # if using chemformula

# down

# push

# down

# <push, push, xxx, right, xxx, pop, pop> # if using xcolor

# down

# push

# down (possibly multiple)

# push <= here, v is the baseline position.

# etc.

# (dviasm is useful to explore this structure.)

# Thus, we use the vertical position at the first time the stack depth

# reaches 3, while at least three "downs" have been executed (excluding

# those popped out (corresponding to the chemformula preamble)), as the

# baseline (the "down" count is necessary to handle xcolor).

down_stack = [0]

self._baseline_v = None

while True:

byte = self.file.read(1)[0]

self._dtable[byte](self, byte)

if self._missing_font:

raise self._missing_font.to_exception()

name = self._dtable[byte].__name__

if name == "_push":

down_stack.append(down_stack[-1])

elif name == "_pop":

down_stack.pop()

elif name == "_down":

down_stack[-1] += 1

if (self._baseline_v is None

and len(getattr(self, "stack", [])) == 3

and down_stack[-1] >= 4):

self._baseline_v = self.v

if byte == 140: # end of page

return True

if self.state is _dvistate.post_post: # end of file

self.close()

return False

def _read_arg(self, nbytes, signed=False):

"""

Read and return a big-endian integer *nbytes* long.

Signedness is determined by the *signed* keyword.

"""

return int.from_bytes(self.file.read(nbytes), "big", signed=signed)

@_dispatch(min=0, max=127, state=_dvistate.inpage)

def _set_char_immediate(self, char):

self._put_char_real(char)

if isinstance(self.fonts[self.f], cbook._ExceptionInfo):

return

self.h += self.fonts[self.f]._width_of(char)

@_dispatch(min=128, max=131, state=_dvistate.inpage, args=('olen1',))

def _set_char(self, char):

self._put_char_real(char)

if isinstance(self.fonts[self.f], cbook._ExceptionInfo):

return

self.h += self.fonts[self.f]._width_of(char)

@_dispatch(132, state=_dvistate.inpage, args=('s4', 's4'))

def _set_rule(self, a, b):

self._put_rule_real(a, b)

self.h += b

@_dispatch(min=133, max=136, state=_dvistate.inpage, args=('olen1',))

def _put_char(self, char):

self._put_char_real(char)

def _put_char_real(self, char):

font = self.fonts[self.f]

if isinstance(font, cbook._ExceptionInfo):

self._missing_font = font

elif font._vf is None:

self.text.append(Text(self.h, self.v, font, char,

font._width_of(char)))

else:

scale = font._scale

for x, y, f, g, w in font._vf[char].text:

newf = DviFont(scale=_mul1220(scale, f._scale),

metrics=f._metrics, texname=f.texname, vf=f._vf)

self.text.append(Text(self.h + _mul1220(x, scale),

self.v + _mul1220(y, scale),

newf, g, newf._width_of(g)))

self.boxes.extend([Box(self.h + _mul1220(x, scale),

self.v + _mul1220(y, scale),

_mul1220(a, scale), _mul1220(b, scale))

for x, y, a, b in font._vf[char].boxes])

@_dispatch(137, state=_dvistate.inpage, args=('s4', 's4'))

def _put_rule(self, a, b):

self._put_rule_real(a, b)

def _put_rule_real(self, a, b):

if a > 0 and b > 0:

self.boxes.append(Box(self.h, self.v, a, b))

@_dispatch(138)

def _nop(self, _):

pass

@_dispatch(139, state=_dvistate.outer, args=('s4',)*11)

def _bop(self, c0, c1, c2, c3, c4, c5, c6, c7, c8, c9, p):

self.state = _dvistate.inpage

self.h = self.v = self.w = self.x = self.y = self.z = 0

self.stack = []

self.text = [] # list of Text objects

self.boxes = [] # list of Box objects

@_dispatch(140, state=_dvistate.inpage)

def _eop(self, _):

self.state = _dvistate.outer

del self.h, self.v, self.w, self.x, self.y, self.z, self.stack

@_dispatch(141, state=_dvistate.inpage)

def _push(self, _):

self.stack.append((self.h, self.v, self.w, self.x, self.y, self.z))

@_dispatch(142, state=_dvistate.inpage)

def _pop(self, _):

self.h, self.v, self.w, self.x, self.y, self.z = self.stack.pop()

@_dispatch(min=143, max=146, state=_dvistate.inpage, args=('slen1',))

def _right(self, b):

self.h += b

@_dispatch(min=147, max=151, state=_dvistate.inpage, args=('slen',))

def _right_w(self, new_w):

if new_w is not None:

self.w = new_w

self.h += self.w

@_dispatch(min=152, max=156, state=_dvistate.inpage, args=('slen',))

def _right_x(self, new_x):

if new_x is not None:

self.x = new_x

self.h += self.x

@_dispatch(min=157, max=160, state=_dvistate.inpage, args=('slen1',))

def _down(self, a):

self.v += a

@_dispatch(min=161, max=165, state=_dvistate.inpage, args=('slen',))

def _down_y(self, new_y):

if new_y is not None:

self.y = new_y

self.v += self.y

@_dispatch(min=166, max=170, state=_dvistate.inpage, args=('slen',))

def _down_z(self, new_z):

if new_z is not None:

self.z = new_z

self.v += self.z

@_dispatch(min=171, max=234, state=_dvistate.inpage)

def _fnt_num_immediate(self, k):

self.f = k

@_dispatch(min=235, max=238, state=_dvistate.inpage, args=('olen1',))

def _fnt_num(self, new_f):

self.f = new_f

@_dispatch(min=239, max=242, args=('ulen1',))

def _xxx(self, datalen):

special = self.file.read(datalen)

_log.debug(

'Dvi._xxx: encountered special: %s',

''.join([chr(ch) if 32 <= ch < 127 else '<%02x>' % ch

for ch in special]))

@_dispatch(min=243, max=246, args=('olen1', 'u4', 'u4', 'u4', 'u1', 'u1'))

def _fnt_def(self, k, c, s, d, a, l):

self._fnt_def_real(k, c, s, d, a, l)

def _fnt_def_real(self, k, c, s, d, a, l):

n = self.file.read(a + l)

fontname = n[-l:]

if fontname.startswith(b"[") and c == 0x4c756146: # c == "LuaF"

# See https://chat.stackexchange.com/rooms/106428 (and also

# https://tug.org/pipermail/dvipdfmx/2021-January/000168.html).

# AFAICT luatex's dvi drops info re: OpenType variation-axis values.

self.fonts[k] = DviFont.from_luatex(s, n)

return

fontname = fontname.decode("ascii")

try:

tfm = _tfmfile(fontname)

except FileNotFoundError as exc:

if fontname.startswith("[") and fontname.endswith(";") and c == 0:

exc.add_note(

"This dvi file was likely generated with a too-old "

"version of luaotfload; luaotfload 3.23 is required.")

# Explicitly allow defining missing fonts for Vf support; we only

# register an error when trying to load a glyph from a missing font

# and throw that error in Dvi._read. For Vf, _finalize_packet

# checks whether a missing glyph has been used, and in that case

# skips the glyph definition.

self.fonts[k] = cbook._ExceptionInfo.from_exception(exc)

return

if c != 0 and tfm.checksum != 0 and c != tfm.checksum:

raise ValueError(f'tfm checksum mismatch: {n}')

try:

vf = _vffile(fontname)

except FileNotFoundError:

vf = None

self.fonts[k] = DviFont(scale=s, metrics=tfm, texname=n, vf=vf)

@_dispatch(247, state=_dvistate.pre, args=('u1', 'u4', 'u4', 'u4', 'u1'))

def _pre(self, i, num, den, mag, k):

self.file.read(k) # comment in the dvi file

if i not in [2, 7]: # 2: pdftex, luatex; 7: xetex

raise ValueError(f"Unknown dvi format {i}")

if num != 25400000 or den != 7227 * 2**16:

raise ValueError("Nonstandard units in dvi file")

# meaning: TeX always uses those exact values, so it

# should be enough for us to support those

# (There are 72.27 pt to an inch so 7227 pt =

# 7227 * 2**16 sp to 100 in. The numerator is multiplied

# by 10^5 to get units of 10**-7 meters.)

if mag != 1000:

raise ValueError("Nonstandard magnification in dvi file")

# meaning: LaTeX seems to frown on setting \mag, so

# I think we can assume this is constant

self.state = _dvistate.outer

@_dispatch(248, state=_dvistate.outer)

def _post(self, _):

self.state = _dvistate.post_post

# TODO: actually read the postamble and finale?

# currently post_post just triggers closing the file

@_dispatch(249, args=())

def _post_post(self):

raise NotImplementedError

@_dispatch(250, args=())

def _begin_reflect(self):

raise NotImplementedError

@_dispatch(251, args=())

def _end_reflect(self):

raise NotImplementedError

@_dispatch(252, args=())

def _define_native_font(self):

k = self._read_arg(4, signed=False)

s = self._read_arg(4, signed=False)

flags = self._read_arg(2, signed=False)

l = self._read_arg(1, signed=False)

n = self.file.read(l)

i = self._read_arg(4, signed=False)

effects = {}

if flags & 0x0200:

effects["rgba"] = [self._read_arg(1, signed=False) for _ in range(4)]

if flags & 0x1000:

effects["extend"] = self._read_arg(4, signed=True) / 65536

if flags & 0x2000:

effects["slant"] = self._read_arg(4, signed=True) / 65536

if flags & 0x4000:

effects["embolden"] = self._read_arg(4, signed=True) / 65536

self.fonts[k] = DviFont.from_xetex(s, n, i, effects)

@_dispatch(253, args=())

def _set_glyphs(self):

w = self._read_arg(4, signed=False)

k = self._read_arg(2, signed=False)

xy = [self._read_arg(4, signed=True) for _ in range(2 * k)]

g = [self._read_arg(2, signed=False) for _ in range(k)]

font = self.fonts[self.f]

for i in range(k):

self.text.append(Text(self.h + xy[2 * i], self.v + xy[2 * i + 1],

font, g[i], font._width_of(g[i])))

self.h += w

@_dispatch(254, args=())

def _set_text_and_glyphs(self):

l = self._read_arg(2, signed=False)

t = self.file.read(2 * l) # utf16

w = self._read_arg(4, signed=False)

k = self._read_arg(2, signed=False)

xy = [self._read_arg(4, signed=True) for _ in range(2 * k)]

g = [self._read_arg(2, signed=False) for _ in range(k)]

font = self.fonts[self.f]

for i in range(k):

self.text.append(Text(self.h + xy[2 * i], self.v + xy[2 * i + 1],

font, g[i], font._width_of(g[i])))

self.h += w

@_dispatch(255)

def _malformed(self, raw):

raise ValueError("unknown command: byte 255")

class DviFont:

"""

Encapsulation of a font that a DVI file can refer to.

This class holds a font's texname and size, supports comparison,

and knows the widths of glyphs in the same units as the AFM file.

There are also internal attributes (for use by dviread.py) that

are *not* used for comparison.

The size is in Adobe points (converted from TeX points).

Parameters

----------

scale : float

Factor by which the font is scaled from its natural size.

metrics : Tfm | TtfMetrics

TeX font metrics for this font

texname : bytes

Name of the font as used internally in the DVI file, as an ASCII

bytestring. This is usually very different from any external font

names; `PsfontsMap` can be used to find the external name of the font.

vf : Vf

A TeX "virtual font" file, or None if this font is not virtual.

Attributes

----------

texname : bytes

fname : str

Compatibility shim so that DviFont can be used with

``_backend_pdf_ps.CharacterTracker``; not a real filename.

size : float

Size of the font in Adobe points, converted from the slightly

smaller TeX points.

"""

def __init__(self, scale, metrics, texname, vf):

_api.check_isinstance(bytes, texname=texname)

self._scale = scale

self._metrics = metrics

self.texname = texname

self._vf = vf

self._path = None

self._encoding = None

@classmethod

def from_luatex(cls, scale, texname):

path_b, sep, rest = texname[1:].rpartition(b"]")

if not (texname.startswith(b"[") and sep and rest[:1] in [b"", b":"]):

raise ValueError(f"Invalid modern font name: {texname}")

# utf8 on Windows, not utf16!

path = path_b.decode("utf8") if os.name == "nt" else os.fsdecode(path_b)

subfont = 0

effects = {}

if rest[1:]:

for kv in rest[1:].decode("ascii").split(";"):

key, val = kv.split("=", 1)

if key == "index":

subfont = val

elif key in ["embolden", "slant", "extend"]:

effects[key] = int(val) / 65536

else:

_log.warning("Ignoring invalid key-value pair: %r", kv)

metrics = TtfMetrics(path)

font = cls(scale, metrics, texname, vf=None)

font._path = Path(path)

font.subfont = subfont

font.effects = effects

return font

@classmethod

def from_xetex(cls, scale, texname, subfont, effects):

# utf8 on Windows, not utf16!

path = texname.decode("utf8") if os.name == "nt" else os.fsdecode(texname)

metrics = TtfMetrics(path)

font = cls(scale, metrics, b"[" + texname + b"]", vf=None)

font._path = Path(path)

font.subfont = subfont

font.effects = effects

return font

size = property(lambda self: self._scale * (72.0 / (72.27 * 2**16)))

widths = _api.deprecated("3.11")(property(lambda self: [

(1000 * self._tfm.width.get(char, 0)) >> 20

for char in range(max(self._tfm.width, default=-1) + 1)]))

@property

def fname(self):

"""A fake filename"""

return self.texname.decode('latin-1')

@property

def face_index(self): # For compatibility with FT2Font.

return 0

def _get_fontmap(self, string):

"""Get the mapping from characters to the font that includes them.

Each value maps to self; there is no fallback mechanism for DviFont.

"""

return {char: self for char in string}

def __eq__(self, other):

return (type(self) is type(other)

and self.texname == other.texname and self.size == other.size)

def __ne__(self, other):

return not self.__eq__(other)

def __repr__(self):

return f"<{type(self).__name__}: {self.texname}>"

def _width_of(self, char):

"""Width of char in dvi units."""

metrics = self._metrics.get_metrics(char)

if metrics is None:

_log.debug('No width for char %d in font %s.', char, self.texname)

return 0

return _mul1220(metrics.tex_width, self._scale)

def _height_depth_of(self, char):

"""Height and depth of char in dvi units."""

metrics = self._metrics.get_metrics(char)

if metrics is None:

_log.debug('No metrics for char %d in font %s', char, self.texname)

return [0, 0]

hd = [

_mul1220(metrics.tex_height, self._scale),

_mul1220(metrics.tex_depth, self._scale),

]

# cmsyXX (symbols font) glyph 0 ("minus") has a nonzero descent

# so that TeX aligns equations properly

# (https://tex.stackexchange.com/q/526103/)

# but we actually care about the rasterization depth to align

# the dvipng-generated images.

if re.match(br'^cmsy\d+$', self.texname) and char == 0:

hd[-1] = 0

return hd

def resolve_path(self):

if self._path is None:

fontmap = PsfontsMap(find_tex_file("pdftex.map"))

try:

psfont = fontmap[self.texname]

except LookupError as exc:

try:

find_tex_file(f"{self.texname.decode('ascii')}.mf")

except FileNotFoundError:

raise exc from None

else:

self._path = Path(find_tex_file(

f"{self.texname.decode('ascii')}.600pk"))

else:

if psfont.filename is None:

raise ValueError("No usable font file found for {} ({}); "

"the font may lack a Type-1 version"

.format(psfont.psname.decode("ascii"),

psfont.texname.decode("ascii")))

self._path = Path(psfont.filename)

return self._path

@cached_property

def subfont(self):

return 0

@cached_property

def effects(self):

if self.resolve_path().match("*.600pk"):

return {}

return PsfontsMap(find_tex_file("pdftex.map"))[self.texname].effects

def _index_dvi_to_freetype(self, idx):

"""Convert dvi glyph indices to FreeType ones."""

# Glyphs indices stored in the dvi file map to FreeType glyph indices

# (i.e., which can be passed to FT_Load_Glyph) in various ways:

# - for xetex & luatex "native fonts", dvi indices are directly equal

# to FreeType indices.

# - if pdftex.map specifies an ".enc" file for the font, that file maps

# dvi indices to Adobe glyph names, which can then be converted to

# FreeType glyph indices with FT_Get_Name_Index.

# - if no ".enc" file is specified, then the font must be a Type 1

# font, and dvi indices directly index into the font's CharStrings

# vector.

if self.texname.startswith(b"["):

return idx

if self._encoding is None:

face = font_manager.get_font(self.resolve_path())

psfont = PsfontsMap(find_tex_file("pdftex.map"))[self.texname]

if psfont.encoding:

self._encoding = [face.get_name_index(name)

for name in _parse_enc(psfont.encoding)]

else:

self._encoding = face._get_type1_encoding_vector()

return self._encoding[idx]

class Vf(Dvi):

r"""

A virtual font (\*.vf file) containing subroutines for dvi files.

Parameters

----------

filename : str or path-like

Notes

-----

The virtual font format is a derivative of dvi:

http://mirrors.ctan.org/info/knuth/virtual-fonts

This class reuses some of the machinery of `Dvi`

but replaces the `!_read` loop and dispatch mechanism.

Examples

--------

::

vf = Vf(filename)

glyph = vf[code]

glyph.text, glyph.boxes, glyph.width

"""

def __init__(self, filename):

super().__init__(filename, 0)

try:

self._first_font = None

self._chars = {}

self._read()

finally:

self.close()

def __getitem__(self, code):

return self._chars[code]

def _read(self):

"""

Read one page from the file. Return True if successful,

False if there were no more pages.

"""

packet_char = packet_ends = None

packet_len = packet_width = None

while True:

byte = self.file.read(1)[0]

# If we are in a packet, execute the dvi instructions

if self.state is _dvistate.inpage:

byte_at = self.file.tell()-1

if byte_at == packet_ends:

self._finalize_packet(packet_char, packet_width)

packet_len = packet_char = packet_width = None

# fall through to out-of-packet code

elif byte_at > packet_ends:

raise ValueError("Packet length mismatch in vf file")

else:

if byte in (139, 140) or byte >= 243:

raise ValueError(f"Inappropriate opcode {byte} in vf file")

Dvi._dtable[byte](self, byte)

continue

# We are outside a packet

if byte < 242: # a short packet (length given by byte)

packet_len = byte

packet_char = self._read_arg(1)

packet_width = self._read_arg(3)

packet_ends = self._init_packet(byte)

self.state = _dvistate.inpage

elif byte == 242: # a long packet

packet_len = self._read_arg(4)

packet_char = self._read_arg(4)

packet_width = self._read_arg(4)

self._init_packet(packet_len)

elif 243 <= byte <= 246:

k = self._read_arg(byte - 242, byte == 246)

c = self._read_arg(4)

s = self._read_arg(4)

d = self._read_arg(4)

a = self._read_arg(1)

l = self._read_arg(1)

self._fnt_def_real(k, c, s, d, a, l)

if self._first_font is None:

self._first_font = k

elif byte == 247: # preamble

i = self._read_arg(1)

k = self._read_arg(1)

x = self.file.read(k)

cs = self._read_arg(4)

ds = self._read_arg(4)

self._pre(i, x, cs, ds)

elif byte == 248: # postamble (just some number of 248s)

break

else:

raise ValueError(f"Unknown vf opcode {byte}")

def _init_packet(self, pl):

if self.state != _dvistate.outer:

raise ValueError("Misplaced packet in vf file")

self.h = self.v = self.w = self.x = self.y = self.z = 0

self.stack = []

self.text = []

self.boxes = []

self.f = self._first_font

self._missing_font = None

return self.file.tell() + pl

def _finalize_packet(self, packet_char, packet_width):

if not self._missing_font: # Otherwise we don't have full glyph definition.

self._chars[packet_char] = Page(

text=self.text, boxes=self.boxes, width=packet_width,

height=None, descent=None)

self.state = _dvistate.outer

def _pre(self, i, x, cs, ds):

if self.state is not _dvistate.pre:

raise ValueError("pre command in middle of vf file")

if i != 202:

raise ValueError(f"Unknown vf format {i}")

if len(x):

_log.debug('vf file comment: %s', x)

self.state = _dvistate.outer

# cs = checksum, ds = design size

def _mul1220(num1, num2):

"""Multiply two numbers in 12.20 fixed point format."""

# Separated into a function because >> has surprising precedence

return (num1*num2) >> 20

@dataclasses.dataclass(frozen=True, kw_only=True)

class TexMetrics:

"""

Metrics of a glyph, with TeX semantics.

TeX metrics have different semantics from FreeType metrics: tex_width

corresponds to FreeType's ``advance`` (i.e., including whitespace padding);

tex_height to ``bearingY`` (how much the glyph extends over the baseline);

tex_depth to ``height - bearingY`` (how much the glyph extends under the

baseline, as a positive number).

"""

tex_width: int

tex_height: int

tex_depth: int

class Tfm:

"""

A TeX Font Metric file.

This implementation covers only the bare minimum needed by the Dvi class.

Parameters

----------

filename : str or path-like

Attributes

----------

checksum : int

Used for verifying against the dvi file.

design_size : int

Design size of the font (in 12.20 TeX points); unused because it is

overridden by the scale factor specified in the dvi file.

"""

def __init__(self, filename):

_log.debug('opening tfm file %s', filename)

with open(filename, 'rb') as file:

header1 = file.read(24)

lh, bc, ec, nw, nh, nd = struct.unpack('!6H', header1[2:14])

_log.debug('lh=%d, bc=%d, ec=%d, nw=%d, nh=%d, nd=%d',

lh, bc, ec, nw, nh, nd)

header2 = file.read(4*lh)

self.checksum, self.design_size = struct.unpack('!2I', header2[:8])

# there is also encoding information etc.