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Fix margins #28

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merged 3 commits into from
Feb 1, 2022
Merged

Fix margins #28

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3f6cd52
fix Margin calculations
bertsky Jan 31, 2022
ba7d0fc
convert_text: assign regions to PrintSpace or Margins by bbox
bertsky Jan 31, 2022
6f6394c
not is → is not
bertsky Jan 31, 2022
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112 changes: 67 additions & 45 deletions ocrd_page_to_alto/convert.py
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Original file line number Diff line number Diff line change
Expand Up @@ -10,14 +10,15 @@
parseString,
to_xml)
from ocrd_models.constants import NAMESPACES as NAMESPACES_
from ocrd_utils import getLogger, xywh_from_points
from ocrd_utils import getLogger, bbox_from_points

from .utils import (
set_alto_id_from_page_id,
set_alto_lang_from_page_lang,
set_alto_shape_from_coords,
set_alto_xywh_from_coords,
setxml,
contains,
get_nth_textequiv)
from .styles import TextStylesManager, ParagraphStyleManager, LayoutTagManager

Expand Down Expand Up @@ -183,55 +184,60 @@ def convert_border(self):
page_height = self.page_page.imageHeight
setxml(self.alto_page, 'WIDTH', page_width)
setxml(self.alto_page, 'HEIGHT', page_height)
page_printspace = self.page_page.get_PrintSpace()
dummy_printspace = False
if page_printspace is None:
self.logger.warning("PAGE-XML has no PrintSpace, trying to fall back to Border")
page_printspace = self.page_page.get_Border()
if page_printspace is None:
dummy_printspace = True
page_border = self.page_page.get_Border()
page_pspace = self.page_page.get_PrintSpace()
if page_pspace is None and not page_border is None:
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self.logger.warning("PAGE-XML has Border but no PrintSpace - Margins will be empty")
page_pspace = page_border
elif page_border is None and not page_pspace is None:
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self.logger.warning("PAGE-XML has PrintSpace but no Border - Margins will be empty")
page_border = page_pspace
elif page_border is None and page_pspace is None:
self.logger.warning("PAGE-XML has neither Border nor PrintSpace - PrintSpace will fill the image")
alto_pspace = ET.SubElement(self.alto_page, 'PrintSpace')
setxml(alto_pspace, 'VPOS', 0)
setxml(alto_pspace, 'HPOS', 0)
setxml(alto_pspace, 'HEIGHT', page_height)
setxml(alto_pspace, 'WIDTH', page_width)
return alto_pspace

if dummy_printspace:
self.logger.warning("PAGE-XML has neither Border nor PrintSpace")
for pos in ('Top', 'Left', 'Right', 'Bottom'):
margin = ET.SubElement(self.alto_page, '%sMargin' % pos)
for att in ('VPOS', 'HPOS', 'HEIGHT', 'WIDTH'):
setxml(margin, att, 0)
else:
xywh = xywh_from_points(page_printspace.get_Coords().points)
alto_pspace = ET.SubElement(self.alto_page, 'PrintSpace')
set_alto_xywh_from_coords(alto_pspace, page_pspace)
set_alto_shape_from_coords(alto_pspace, page_pspace)

if not page_border is page_pspace:
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bmin_x, bmin_y, bmax_x, bmax_y = bbox_from_points(page_border.get_Coords().points)
pmin_x, pmin_y, pmax_x, pmax_y = bbox_from_points(page_pspace.get_Coords().points)
#
# ╔═══════╗ ╔═══════╗ ╔╗ ╔══╗
# ║┌───┐ ║ ╚═══════╝ ║║ ║ ║ ┌───┐
# ║│ │ ║ → + ║║ ║ ║ (margins) + │ │ (pspace)
# ║└───┘ ║ ╔═══════╗ ║║ ║ ║ └───┘
# ║ ║ ║ ║ ║║ ║ ║
# ╚═══════╝ ╚═══════╝ ╚╝ ╚══╝
#
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Very useful. Pretty, too.

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Unfortunately, PRImA libs do not handle ALTO that way:

https://github.com/PRImA-Research-Lab/prima-core-libs/blob/1f087a4378f58a34c83176ab0ffb620dd8b78f2d/java/PrimaDla/src/org/primaresearch/dla/page/io/xml/sax/SaxPageHandler_Alto_2_1.java#L402-L429

https://github.com/PRImA-Research-Lab/prima-core-libs/blob/1f087a4378f58a34c83176ab0ffb620dd8b78f2d/java/PrimaDla/src/org/primaresearch/dla/page/io/xml/XmlPageWriter_Alto.java#L463-L529

(They ignore Border and treat the margins as anything beyond the PrintSpace.)

alto_topmargin = ET.SubElement(self.alto_page, 'TopMargin')
setxml(alto_topmargin, 'VPOS', 0)
setxml(alto_topmargin, 'HPOS', 0)
setxml(alto_topmargin, 'HEIGHT', xywh['x'])
setxml(alto_topmargin, 'WIDTH', page_width)
setxml(alto_topmargin, 'VPOS', bmin_y)
setxml(alto_topmargin, 'HPOS', bmin_x)
setxml(alto_topmargin, 'HEIGHT', pmin_y - bmin_y)
setxml(alto_topmargin, 'WIDTH', bmax_x - bmin_x)
alto_leftmargin = ET.SubElement(self.alto_page, 'LeftMargin')
setxml(alto_leftmargin, 'VPOS', 0)
setxml(alto_leftmargin, 'HPOS', 0)
setxml(alto_leftmargin, 'HEIGHT', page_height)
setxml(alto_leftmargin, 'WIDTH', xywh['x'])
setxml(alto_leftmargin, 'VPOS', bmin_y)
setxml(alto_leftmargin, 'HPOS', bmin_x)
setxml(alto_leftmargin, 'HEIGHT', bmax_y - bmin_y)
setxml(alto_leftmargin, 'WIDTH', pmin_x - bmin_x)
alto_rightmargin = ET.SubElement(self.alto_page, 'RightMargin')
setxml(alto_rightmargin, 'VPOS', 0)
setxml(alto_rightmargin, 'HPOS', xywh['x'] + xywh['w'])
setxml(alto_rightmargin, 'HEIGHT', page_height)
setxml(alto_rightmargin, 'WIDTH', page_width - (xywh['x'] + xywh['w']))
setxml(alto_rightmargin, 'VPOS', bmin_y)
setxml(alto_rightmargin, 'HPOS', pmax_x)
setxml(alto_rightmargin, 'HEIGHT', bmax_y - bmin_y)
setxml(alto_rightmargin, 'WIDTH', bmax_x - pmax_x)
alto_bottommargin = ET.SubElement(self.alto_page, 'BottomMargin')
setxml(alto_bottommargin, 'VPOS', xywh['y'] + xywh['h'])
setxml(alto_bottommargin, 'HPOS', 0)
setxml(alto_bottommargin, 'HEIGHT', page_height - (xywh['y'] + xywh['h']))
setxml(alto_bottommargin, 'WIDTH', page_width)
alto_printspace = ET.SubElement(self.alto_page, 'PrintSpace')
set_alto_xywh_from_coords(alto_printspace, page_printspace)
if version.parse(self.alto_version) >= version.parse('3.1'):
set_alto_shape_from_coords(alto_printspace, page_printspace)
setxml(alto_bottommargin, 'VPOS', pmax_y)
setxml(alto_bottommargin, 'HPOS', bmin_x)
setxml(alto_bottommargin, 'HEIGHT', bmax_y - pmax_y)
setxml(alto_bottommargin, 'WIDTH', bmax_x - bmin_x)

if dummy_printspace:
alto_printspace = ET.SubElement(self.alto_page, 'PrintSpace')
setxml(alto_printspace, 'VPOS', 0)
setxml(alto_printspace, 'HPOS', 0)
setxml(alto_printspace, 'HEIGHT', page_height)
setxml(alto_printspace, 'WIDTH', page_width)

return alto_printspace
return alto_pspace

def convert_metadata(self):
alto_measurementunit = ET.SubElement(self.alto_description, 'MeasurementUnit')
Expand Down Expand Up @@ -333,7 +339,23 @@ def convert_text(self):
reg_alto_type = REGION_PAGE_TO_ALTO[reg_page_type]
if not reg_alto_type:
raise ValueError("Cannot handle PAGE-XML %sRegion" % reg_page_type)
reg_alto = ET.SubElement(self.alto_printspace, reg_alto_type)
# determine if the region belongs to PrintSpace or to any of the Margins
reg_bbox = bbox_from_points(reg_page.get_Coords().points)
if contains(self.alto_printspace, reg_bbox):
parent = self.alto_printspace
else:
parent = None
for margin in ['LeftMargin', 'RightMargin', 'TopMargin', 'BottomMargin']:
if not hasattr(self.alto_page, margin):
continue
margin = getattr(self.alto_page, margin)
if contains(margin, reg_bbox):
parent = margin
break # pick first match only
if not parent:
parent = self.alto_printspace
self.logger.warning("region '%s' not properly contained in PrintSpace or Margins", reg_page.id)
reg_alto = ET.SubElement(parent, reg_alto_type)
set_alto_id_from_page_id(reg_alto, reg_page)
set_alto_xywh_from_coords(reg_alto, reg_page)
if version.parse(self.alto_version) >= version.parse('3.1'):
Expand Down
15 changes: 15 additions & 0 deletions ocrd_page_to_alto/utils.py
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Original file line number Diff line number Diff line change
Expand Up @@ -49,3 +49,18 @@ def get_nth_textequiv(reg_page, textequiv_index, textequiv_fallback_strategy):
else:
return textequivs[textequiv_index].Unicode

def contains(el, bbox):
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If we move forward with ALTO support in core this might be a useful addition to ocrds_utils.

minx1, miny1, maxx1, maxy1 = bbox
minx2 = int(el.get('HPOS'))
miny2 = int(el.get('VPOS'))
maxx2 = minx2 + int(el.get('WIDTH'))
maxy2 = miny2 + int(el.get('HEIGHT'))
if minx1 < minx2:
return False
if maxx1 > maxx2:
return False
if miny1 < miny2:
return False
if maxy1 > maxy2:
return False
return True