from typing import Iterable, List, Literal, Optional, Sequence, Tuple
from manuscript.data import Block, Line, Page, TextSpan
from .geometry import merge_polygons
MergeMethod = Literal["bbox", "convex_hull"]
CollapseLevel = Literal["line", "block"]
def _iter_block_text_spans(block: Block) -> Iterable[TextSpan]:
for line in block.lines:
yield from line.text_spans
def _mean_or_none(values: Sequence[Optional[float]]) -> Optional[float]:
present = [float(value) for value in values if value is not None]
if not present:
return None
return sum(present) / len(present)
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def merge_text_spans(
text_spans: Sequence[TextSpan],
method: MergeMethod = "bbox",
) -> Optional[TextSpan]:
"""
Merge multiple ``TextSpan`` objects into a single wider ``TextSpan``.
Parameters
----------
text_spans : sequence of TextSpan
Input text spans to merge.
method : {"bbox", "convex_hull"}, optional
Polygon merge strategy. ``"bbox"`` creates an axis-aligned rectangle
covering all span polygons. ``"convex_hull"`` creates a convex hull
around all polygon vertices. Default is ``"bbox"``.
Returns
-------
TextSpan or None
Merged text span, or ``None`` when ``text_spans`` is empty.
"""
if not text_spans:
return None
polygon = merge_polygons([text_span.polygon for text_span in text_spans], method=method)
if polygon is None:
return None
texts = [text_span.text.strip() for text_span in text_spans if text_span.text]
text = " ".join(texts) if texts else None
return TextSpan(
polygon=polygon,
detection_confidence=sum(
float(text_span.detection_confidence) for text_span in text_spans
)
/ len(text_spans),
text=text,
recognition_confidence=_mean_or_none(
[text_span.recognition_confidence for text_span in text_spans]
),
order=0,
)
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def collapse_line_text_spans(
line: Line,
method: MergeMethod = "bbox",
) -> Line:
"""
Collapse all text spans inside a line into a single text span.
Parameters
----------
line : Line
Input line.
method : {"bbox", "convex_hull"}, optional
Polygon merge strategy. Default is ``"bbox"``.
Returns
-------
Line
New line containing one merged text span or an empty span list.
"""
merged = merge_text_spans(line.text_spans, method=method)
return Line(
text_spans=[] if merged is None else [merged],
order=line.order,
)
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def collapse_block_text_spans(
block: Block,
method: MergeMethod = "bbox",
) -> Block:
"""
Collapse all text spans inside a block into a single line with one text span.
Parameters
----------
block : Block
Input block.
method : {"bbox", "convex_hull"}, optional
Polygon merge strategy. Default is ``"bbox"``.
Returns
-------
Block
New block containing a single collapsed line.
"""
merged = merge_text_spans(list(_iter_block_text_spans(block)), method=method)
return Block(
lines=[Line(text_spans=[] if merged is None else [merged], order=0)],
order=block.order,
)
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def collapse_page_text_spans(
page: Page,
level: CollapseLevel = "line",
method: MergeMethod = "bbox",
) -> Page:
"""
Collapse narrow OCR structure into wider line-level or block-level spans.
Parameters
----------
page : Page
Input page.
level : {"line", "block"}, optional
Collapse target. ``"line"`` keeps the same block/line structure and
replaces each line with one merged text span. ``"block"`` replaces each
block with one line containing one merged text span. Default is ``"line"``.
method : {"bbox", "convex_hull"}, optional
Polygon merge strategy. Default is ``"bbox"``.
Returns
-------
Page
Collapsed page.
"""
if level not in {"line", "block"}:
raise ValueError(f"level must be 'line' or 'block', got: {level}")
if level == "line":
return Page(
blocks=[
Block(
lines=[
collapse_line_text_spans(line, method=method)
for line in block.lines
],
order=block.order,
)
for block in page.blocks
]
)
return Page(
blocks=[
collapse_block_text_spans(block, method=method)
for block in page.blocks
]
)
__all__ = [
"collapse_block_text_spans",
"collapse_line_text_spans",
"collapse_page_text_spans",
"merge_text_spans",
]