modm_data.pdf2html.line

 1# Copyright 2022, Niklas Hauser
 2# SPDX-License-Identifier: MPL-2.0
 3
 4from functools import cached_property
 5from ..utils import Rectangle
 6
 7
 8class CharCluster:
 9    """
10    A cluster of characters separated by less than two space-widths.
11    These denote the use of additional white space that is not encoded in the
12    character stream of the PDF page.
13    """
14
15    def __init__(self, line, chars: list):
16        self._line = line
17        self.chars = chars
18
19    @cached_property
20    def content(self) -> str:
21        return "".join(c.char for c in self.chars)
22
23    @cached_property
24    def bbox(self) -> Rectangle:
25        return Rectangle(min(c.bbox.left for c in self.chars),
26                         min(c.bbox.bottom for c in self.chars),
27                         max(c.bbox.right for c in self.chars),
28                         max(c.bbox.top for c in self.chars))
29
30
31class CharLine:
32    """
33    A line of characters with super- and sub-script chars merged into.
34    """
35
36    def __init__(self, page, chars: list, bottom: float,
37                 origin: float, top: float,
38                 height: float = None, rotation: int = 0,
39                 offset: float = 0, sort_origin: float = None):
40        self._page = page
41        self.chars = chars
42        self.bottom = bottom
43        self.origin = origin
44        self.top = top
45        self.height = height or (top - bottom)
46        self.rotation = rotation
47        self.offset = offset
48        self._sort_origin = origin if sort_origin is None else sort_origin
49
50    @cached_property
51    def bbox(self) -> Rectangle:
52        return Rectangle(min(c.bbox.left for c in self.chars),
53                         min(c.bbox.bottom for c in self.chars),
54                         max(c.bbox.right for c in self.chars),
55                         max(c.bbox.top for c in self.chars))
56
57    @cached_property
58    def fonts(self) -> set:
59        return set(c.font for c in self.chars if c.font)
60
61    def contains_font(self, *fragments) -> bool:
62        for fragment in fragments:
63            if any(fragment in font for font in self.fonts):
64                return True
65        return False
66
67    @cached_property
68    def content(self) -> str:
69        return "".join(c.char for c in self.chars)
70
71    def clusters(self, atol: float = None) -> list[CharCluster]:
72        # Find clusters of characters in a line incl. whitespace chars
73        def _cluster(clusters, chars):
74            if chars:
75                clusters.append(CharCluster(self, chars))
76
77        # We want to group the chars if the space between them is > 1em
78        if atol is None:
79            atol = self._page._spacing["x_em"] * 1
80        clusters = []
81        current_chars = [self.chars[0]]
82        last_char = current_chars[0]
83        for next_char in self.chars[1:]:
84            if next_char.bbox.left - last_char.bbox.right < atol:
85                # Keep this char in the current cluster
86                current_chars.append(next_char)
87                if next_char.unicode not in {0x20, 0xa, 0xd}:
88                    last_char = next_char
89            else:
90                # Larger spacing detected, create a new cluster
91                _cluster(clusters, current_chars)
92                current_chars = [next_char]
93                last_char = next_char
94        _cluster(clusters, current_chars)
95
96        return clusters
97
98    def __repr__(self) -> str:
99        return f"Line({len(self.chars)})"