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refactor: Improve PDF path rendering and graphic state handling
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- Enhance paint_path method in converter to handle complex PDF path operations
- Add graphic state management for path rendering
- Implement more robust path segment processing
- Introduce get_graphic_state method for consistent state management
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@awwaawwa
awwaawwa committed Feb 19, 2025
1 parent f758060 commit 7aaedfe
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Showing 4 changed files with 218 additions and 35 deletions.
137 changes: 137 additions & 0 deletions babeldoc/converter.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2,14 +2,18 @@
import logging
import re
import unicodedata
from collections.abc import Sequence
from typing import cast

import numpy as np
from pdfminer.converter import PDFConverter
from pdfminer.layout import LTChar
from pdfminer.layout import LTComponent
from pdfminer.layout import LTCurve
from pdfminer.layout import LTFigure
from pdfminer.layout import LTLine
from pdfminer.layout import LTPage
from pdfminer.layout import LTRect
from pdfminer.layout import LTText
from pdfminer.pdfcolor import PDFColorSpace
from pdfminer.pdffont import PDFCIDFont
Expand All @@ -18,6 +22,8 @@
from pdfminer.pdfinterp import PDFGraphicState
from pdfminer.pdfinterp import PDFResourceManager
from pdfminer.utils import Matrix
from pdfminer.utils import PathSegment
from pdfminer.utils import Point
from pdfminer.utils import apply_matrix_pt
from pdfminer.utils import bbox2str
from pdfminer.utils import matrix2str
Expand Down Expand Up @@ -120,6 +126,133 @@ def render_char(
item.font = font # hack 插入原字符字体
return item.adv

def paint_path(
self,
gstate: PDFGraphicState,
stroke: bool,
fill: bool,
evenodd: bool,
path: Sequence[PathSegment],
graphicstate: PDFGraphicState,
) -> None:
"""Paint paths described in section 4.4 of the PDF reference manual"""
shape = "".join(x[0] for x in path)

if shape[:1] != "m":
# Per PDF Reference Section 4.4.1, "path construction operators may
# be invoked in any sequence, but the first one invoked must be m
# or re to begin a new subpath." Since pdfminer.six already
# converts all `re` (rectangle) operators to their equivelent
# `mlllh` representation, paths ingested by `.paint_path(...)` that
# do not begin with the `m` operator are invalid.
pass

elif shape.count("m") > 1:
# recurse if there are multiple m's in this shape
for m in re.finditer(r"m[^m]+", shape):
subpath = path[m.start(0) : m.end(0)]
self.paint_path(gstate, stroke, fill, evenodd, subpath, graphicstate)

else:
# Although the 'h' command does not not literally provide a
# point-position, its position is (by definition) equal to the
# subpath's starting point.
#
# And, per Section 4.4's Table 4.9, all other path commands place
# their point-position in their final two arguments. (Any preceding
# arguments represent control points on Bézier curves.)
raw_pts = [
cast(Point, p[-2:] if p[0] != "h" else path[0][-2:]) for p in path
]
pts = [apply_matrix_pt(self.ctm, pt) for pt in raw_pts]

operators = [str(operation[0]) for operation in path]
transformed_points = [
[
apply_matrix_pt(self.ctm, (float(operand1), float(operand2)))
for operand1, operand2 in zip(
operation[1::2],
operation[2::2],
strict=False,
)
]
for operation in path
]
transformed_path = [
cast(PathSegment, (o, *p))
for o, p in zip(operators, transformed_points, strict=False)
]

if shape in {"mlh", "ml"}:
# single line segment
#
# Note: 'ml', in conditional above, is a frequent anomaly
# that we want to support.
line = LTLine(
gstate.linewidth,
pts[0],
pts[1],
stroke,
fill,
evenodd,
gstate.scolor,
gstate.ncolor,
original_path=transformed_path,
dashing_style=gstate.dash,
)
line.graphicstate = graphicstate
self.cur_item.add(line)

elif shape in {"mlllh", "mllll"}:
(x0, y0), (x1, y1), (x2, y2), (x3, y3), _ = pts

is_closed_loop = pts[0] == pts[4]
has_square_coordinates = (
x0 == x1 and y1 == y2 and x2 == x3 and y3 == y0
) or (y0 == y1 and x1 == x2 and y2 == y3 and x3 == x0)
if is_closed_loop and has_square_coordinates:
rect = LTRect(
gstate.linewidth,
(*pts[0], *pts[2]),
stroke,
fill,
evenodd,
gstate.scolor,
gstate.ncolor,
transformed_path,
gstate.dash,
)
rect.graphicstate = graphicstate
self.cur_item.add(rect)
else:
curve = LTCurve(
gstate.linewidth,
pts,
stroke,
fill,
evenodd,
gstate.scolor,
gstate.ncolor,
transformed_path,
gstate.dash,
)
curve.graphicstate = graphicstate
self.cur_item.add(curve)
else:
curve = LTCurve(
gstate.linewidth,
pts,
stroke,
fill,
evenodd,
gstate.scolor,
gstate.ncolor,
transformed_path,
gstate.dash,
)
curve.graphicstate = graphicstate
self.cur_item.add(curve)


class AWLTChar(LTChar):
"""Actual letter in the text as a Unicode string."""
Expand Down Expand Up @@ -384,6 +517,10 @@ def vflag(font: str, char: str): # 匹配公式（和角标）字体
vlstk.append(child)
else: # 全局线条
lstk.append(child)
elif isinstance(child, LTCurve):
pass
elif isinstance(child, LTRect):
pass
else:
pass
return
Expand Down
9 changes: 8 additions & 1 deletion babeldoc/document_il/frontend/il_creater.py
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Original file line number Diff line number Diff line change
Expand Up @@ -34,12 +34,19 @@ def __init__(self, translation_config: TranslationConfig):
self.xobj_inc = 0
self.xobj_map: dict[int, il_version_1.PdfXobject] = {}
self.xobj_stack = []
color_pattern = r"sc|scn|g|rg|k|cs|gs|ri"
line_pattern = r"w|j|M|d|i"

self.PASSTHROUGH_PER_CHAR_PATTERN = re.compile(
f"^({color_pattern}|{line_pattern})$",
re.IGNORECASE,
)

def on_finish(self):
self.progress.__exit__(None, None, None)

def is_passthrough_per_char_operation(self, operator: str):
return re.match("^(sc|scn|g|rg|k|cs|gs|ri)$", operator, re.IGNORECASE)
return self.PASSTHROUGH_PER_CHAR_PATTERN.match(operator)

def on_passthrough_per_char(self, operator: str, args: list[str]):
if not self.is_passthrough_per_char_operation(operator):
Expand Down
6 changes: 3 additions & 3 deletions babeldoc/document_il/translator/cache.py
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@
from peewee import SqliteDatabase
from peewee import TextField

from babeldoc.const import CACHE_FOLDER as cache_folder
from babeldoc.const import CACHE_FOLDER

# we don't init the database here
db = SqliteDatabase(None)
Expand Down Expand Up @@ -94,9 +94,9 @@ def set(self, original_text: str, translation: str):


def init_db(remove_exists=False):
cache_folder.mkdir(parents=True, exist_ok=True)
CACHE_FOLDER.mkdir(parents=True, exist_ok=True)
# The current version does not support database migration, so add the version number to the file name.
cache_db_path = cache_folder / "cache.v1.db"
cache_db_path = CACHE_FOLDER / "cache.v1.db"
if remove_exists and cache_db_path.exists():
cache_db_path.unlink()
db.init(
Expand Down
101 changes: 70 additions & 31 deletions babeldoc/pdfinterp.py
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Original file line number Diff line number Diff line change
Expand Up @@ -121,29 +121,42 @@ def get_colorspace(spec: object) -> PDFColorSpace | None:
pass

def do_S(self) -> None:
# 重载过滤非公式线条
"""Stroke path"""
self.device.paint_path(
self.graphicstate,
True,
False,
False,
self.curpath,
self.get_graphic_state(),
)
self.curpath = []
return

def is_black(color: Color) -> bool:
if isinstance(color, tuple):
return sum(color) == 0
else:
return color == 0

if (
len(self.curpath) == 2
and self.curpath[0][0] == "m"
and self.curpath[1][0] == "l"
and apply_matrix_pt(self.ctm, self.curpath[0][-2:])[1]
== apply_matrix_pt(self.ctm, self.curpath[1][-2:])[1]
and is_black(self.graphicstate.scolor)
): # 独立直线，水平，黑色
# print(apply_matrix_pt(self.ctm,self.curpath[0][-2:]),apply_matrix_pt(self.ctm,self.curpath[1][-2:]),self.graphicstate.scolor)
self.device.paint_path(self.graphicstate, True, False, False, self.curpath)
self.curpath = []
return "n"
else:
self.curpath = []
# def do_S(self) -> None:
# # 重载过滤非公式线条
# """Stroke path"""
#
# def is_black(color: Color) -> bool:
# if isinstance(color, tuple):
# return sum(color) == 0
# else:
# return color == 0
#
# if (
# len(self.curpath) == 2
# and self.curpath[0][0] == "m"
# and self.curpath[1][0] == "l"
# and apply_matrix_pt(self.ctm, self.curpath[0][-2:])[1]
# == apply_matrix_pt(self.ctm, self.curpath[1][-2:])[1]
# and is_black(self.graphicstate.scolor)
# ): # 独立直线，水平，黑色
# # print(apply_matrix_pt(self.ctm,self.curpath[0][-2:]),apply_matrix_pt(self.ctm,self.curpath[1][-2:]),self.graphicstate.scolor)
# self.device.paint_path(self.graphicstate, True, False, False, self.curpath)
# self.curpath = []
# return "n"
# else:
# self.curpath = []

def do_CS(self, name: PDFStackT) -> None:
"""Set color space for stroking operations
Expand Down Expand Up @@ -172,25 +185,54 @@ def do_cs(self, name: PDFStackT) -> None:
# 重载过滤非公式线条（F/B）
def do_f(self) -> None:
"""Fill path using nonzero winding number rule"""
# self.device.paint_path(self.graphicstate, False, True, False, self.curpath)
gs = self.get_graphic_state()
self.device.paint_path(self.graphicstate, False, True, False, self.curpath, gs)
self.curpath = []

def do_F(self) -> None:
"""Fill path using nonzero winding number rule (obsolete)"""
def get_graphic_state(self):
gs = self.graphicstate.copy()
gs.passthrough_instruction = (
self.il_creater.passthrough_per_char_instruction.copy()
)
return gs

# def do_F(self) -> None:
# """Fill path using nonzero winding number rule (obsolete)"""

def do_f_a(self) -> None:
"""Fill path using even-odd rule"""
# self.device.paint_path(self.graphicstate, False, True, True, self.curpath)
self.device.paint_path(
self.graphicstate,
False,
True,
True,
self.curpath,
self.get_graphic_state(),
)
self.curpath = []

def do_B(self) -> None:
"""Fill and stroke path using nonzero winding number rule"""
# self.device.paint_path(self.graphicstate, True, True, False, self.curpath)
self.device.paint_path(
self.graphicstate,
True,
True,
False,
self.curpath,
self.get_graphic_state(),
)
self.curpath = []

def do_B_a(self) -> None:
"""Fill and stroke path using even-odd rule"""
# self.device.paint_path(self.graphicstate, True, True, True, self.curpath)
self.device.paint_path(
self.graphicstate,
True,
True,
True,
self.curpath,
self.get_graphic_state(),
)
self.curpath = []

############################################################
Expand Down Expand Up @@ -380,10 +422,7 @@ def do_TJ(self, seq: PDFStackT) -> None:
raise PDFInterpreterError("No font specified!")
return
assert self.ncs is not None
gs = self.graphicstate.copy()
gs.passthrough_instruction = (
self.il_creater.passthrough_per_char_instruction.copy()
)
gs = self.get_graphic_state()
self.device.render_string(self.textstate, cast(PDFTextSeq, seq), self.ncs, gs)
return

Expand Down

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