54 lines
1.9 KiB
Python
54 lines
1.9 KiB
Python
"""Bounding box coordinate normalization for Docling output.
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Docling's BoundingBox uses two possible coordinate origins:
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- TOPLEFT: y=0 at top, t < b (t is smaller, closer to origin)
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- BOTTOMLEFT: y=0 at bottom, t > b (t is larger, further from origin)
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The frontend canvas uses TOPLEFT coordinates. This module ensures all
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bboxes are normalized to TOPLEFT [left, top, right, bottom] before
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being sent to the frontend.
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"""
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import logging
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from docling_core.types.doc.base import BoundingBox
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logger = logging.getLogger(__name__)
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# Sentinel value returned when a bbox is invalid or degenerate.
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# A zero-area rect is safe: the frontend draws nothing and hit-testing ignores it.
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EMPTY_BBOX: list[float] = [0.0, 0.0, 0.0, 0.0]
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def to_topleft_list(bbox: BoundingBox, page_height: float) -> list[float]:
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"""Convert a Docling BoundingBox to a [l, t, r, b] list in TOPLEFT origin.
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Validates the result: left < right and top < bottom. If the bbox is
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degenerate (zero or negative area), returns EMPTY_BBOX so the frontend
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silently skips it instead of rendering a broken rectangle.
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Args:
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bbox: Docling BoundingBox (any origin).
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page_height: Height of the page (needed for BOTTOMLEFT conversion).
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Returns:
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[left, top, right, bottom] in TOPLEFT coordinates, or EMPTY_BBOX
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if the bbox is degenerate.
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"""
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normalized = bbox.to_top_left_origin(page_height)
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left, top, right, bottom = normalized.l, normalized.t, normalized.r, normalized.b
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# Degenerate bbox: zero or negative dimensions — skip silently.
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# This can happen with corrupted PDFs or edge-case Docling outputs.
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if right <= left or bottom <= top:
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logger.debug(
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"Degenerate bbox skipped: [%.1f, %.1f, %.1f, %.1f] (page_height=%.1f)",
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left,
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top,
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right,
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bottom,
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page_height,
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)
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return list(EMPTY_BBOX)
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return [left, top, right, bottom]
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