check whether PAGE input has words, toggelable, OCR-D/ocrd_calamari#63

Author: kba

ocrd_page_to_alto/cli.py

@@ -3,13 +3,14 @@
 from ocrd_utils import initLogging
 
 @click.command()
+@click.option('--check-words/--no-check-words', default=True, help='Check whether PAGE-XML contains any Words and fail if not')
 @click.argument('filename')
-def main(filename):
+def main(check_words, filename):
     """
     Convert PAGE to ALTO
     """
     initLogging()
-    converter = OcrdPageAltoConverter(page_filename=filename)
+    converter = OcrdPageAltoConverter(page_filename=filename, check_words=check_words)
     converter.convert()
     print(converter)
 

ocrd_page_to_alto/convert.py

@@ -1,6 +1,6 @@
 # pylint: disable=no-member, c-extension-no-member
 from lxml import etree as ET
-from ocrd_models.ocrd_page import (parse, parseString)
+from ocrd_models.ocrd_page import parse, parseString, to_xml
 from ocrd_models.constants import NAMESPACES as NAMESPACES_
 from ocrd_utils import getLogger, xywh_from_points
 
@@ -36,7 +36,11 @@
 
 class OcrdPageAltoConverter():
 
-    def __init__(self, *, page_filename=None, page_etree=None, pcgts=None, logger=None):
+    def __init__(self, *, check_words=True, page_filename=None, page_etree=None, pcgts=None, logger=None):
+        """
+        Keyword Args:
+            check_words (boolean): Whether to check if PAGE-XML contains any words before conversion and fail if not
+        """
         if not (page_filename or page_etree or pcgts):
             raise ValueError("Must pass either pcgts, page_etree or page_filename to constructor")
         self.logger = logger if logger else getLogger('page-to-alto')
@@ -47,6 +51,10 @@ def __init__(self, *, page_filename=None, page_etree=None, pcgts=None, logger=No
         else:
             self.page_pcgts = parse(page_filename)
         self.page_page = self.page_pcgts.get_Page()
+        if check_words:
+            xml_ = ET.fromstring(to_xml(self.page_pcgts).encode('utf-8'))
+            if xml_.find('.//page:Word', NAMESPACES) is None:
+                raise ValueError("The PAGE-XML to transform contains no Words, hence nothing to convert.")
         # TODO self.check_for_words()
         self.alto_alto, self.alto_description, self.alto_styles, self.alto_tags, self.alto_page = self.create_alto()
         self.alto_printspace = self.convert_border()

tests/test_convert.py

@@ -35,5 +35,9 @@ def test_convert3():
     print(c)
     # assert 0
 
+def test_convert_no_words():
+    with raises(ValueError) as e:
+        OcrdPageAltoConverter(page_filename='tests/assets/SBB0000F29300010000/data/OCR-D-GT-PAGE/FILE_0001_FULLTEXT.xml')
+
 if __name__ == "__main__":
     main([__file__])