py3: Port use of no longer extant elements package

src/calibre/ebooks/lrf/pylrs/pylrs.py

@@ -37,16 +37,11 @@
 #                           Plot, Image (outside of ImageBlock),
 #                           EmpLine, EmpDots
 
-import os, re, codecs, operator
+import os, re, codecs, operator, io
 from xml.sax.saxutils import escape
 from datetime import date
-try:
-    from elementtree.ElementTree import (Element, SubElement)
-    Element, SubElement
-except ImportError:
-    from xml.etree.ElementTree import (Element, SubElement)
+from xml.etree.ElementTree import Element, SubElement, ElementTree
 
-from elements import ElementWriter
 from pylrf import (LrfWriter, LrfObject, LrfTag, LrfToc,
         STREAM_COMPRESSED, LrfTagStream, LrfStreamBase, IMAGE_TYPE_ENCODING,
         BINDING_DIRECTION_ENCODING, LINE_TYPE_ENCODING, LrfFileStream,
@@ -624,12 +619,8 @@ def render(self, f, outputEncodingName='UTF-8'):
         # now, add some newlines to make it easier to look at
 
         _formatXml(root)
-
-        writer = ElementWriter(root, header=True,
-                               sourceEncoding=self.sourceencoding,
-                               spaceBeforeClose=False,
-                               outputEncodingName=outputEncodingName)
-        writer.write(f)
+        tree = ElementTree(element=root)
+        tree.write(f, encoding=outputEncodingName, xml_declaration=True)
 
 
 class BookInformation(Delegator):
@@ -679,9 +670,10 @@ def toLrf(self, lrfWriter):
 
         # fix up the doc info to match the LRF format
         # NB: generates an encoding attribute, which lrs2lrf does not
-        xmlInfo = ElementWriter(info, header=True, sourceEncoding=lrfWriter.getSourceEncoding(),
-                                spaceBeforeClose=False).toString()
-
+        tree = ElementTree(element=info)
+        f = io.BytesIO()
+        tree.write(f, encoding='utf-8', xml_declaration=True)
+        xmlInfo = f.getvalue().decode('utf-8')
         xmlInfo = re.sub(r"<CThumbnail.*?>\n", "", xmlInfo)
         xmlInfo = xmlInfo.replace("SumPage>", "Page>")
         lrfWriter.docInfoXml = xmlInfo