DEV: add _get_page_number_from_indirect in writer

pypdf/_writer.py

@@ -424,6 +424,28 @@ def _get_num_pages(self) -> int:
  pages = cast(Dict[str, Any], self.get_object(self._pages))
  return int(pages[NameObject("/Count")])
 
+ def _get_page_number_by_indirect(
+ self, indirect_reference: Union[None, int, NullObject, IndirectObject]
+ ) -> Optional[int]:
+ """
+ Generate _page_id2num.
+
+ Args:
+ indirect_reference:
+
+ Returns:
+ The page number or None
+ """
+ # to provide same function as in PdfReader
+ if indirect_reference is None or isinstance(indirect_reference, NullObject):
+ return None
+ if isinstance(indirect_reference, int):
+ indirect_reference = IndirectObject(indirect_reference, 0, self)
+ obj = indirect_reference.get_object()
+ if isinstance(obj, PageObject):
+ return obj.page_number
+ return None
+
  @property
  def pages(self) -> List[PageObject]:
  """

tests/test_writer.py

@@ -2011,3 +2011,16 @@ def test_reattach_fields():
  assert isinstance(writer.pages[0]["/Annots"][0], IndirectObject)
  del writer.pages[1]["/Annots"]
  assert len(writer.reattach_fields(writer.pages[1])) == 0
+
+
+def test_get_pagenumber_from_indirectobject():
+ """Test test_get_pagenumber_from_indirectobject"""
+ pdf_path = RESOURCE_ROOT / "crazyones.pdf"
+ writer = PdfWriter(clone_from=pdf_path)
+ assert writer._get_page_number_by_indirect(None) is None
+ assert writer._get_page_number_by_indirect(NullObject()) is None
+
+ ind = writer.pages[0].indirect_reference
+ assert writer._get_page_number_by_indirect(ind) == 0
+ assert writer._get_page_number_by_indirect(ind.idnum) == 0
+ assert writer._get_page_number_by_indirect(ind.idnum + 1) is None