Added missing PDF/a-3 attributes to Embedded File

SubType, CreationDate and ModDate were added

weasyprint/__init__.py

@@ -6,6 +6,8 @@ importing sub-modules.
 """
 
 import contextlib
+import datetime
+import os
 from pathlib import Path
 from urllib.parse import urljoin
 
@@ -267,11 +269,36 @@ class Attachment:
     """
     def __init__(self, guess=None, filename=None, url=None, file_obj=None,
                  string=None, base_url=None, url_fetcher=default_url_fetcher,
-                 description=None):
+                 description=None, created=None, modified=None,
+                 af_relationship="Source"):
         self.source = _select_source(
             guess, filename, url, file_obj, string, base_url=base_url,
             url_fetcher=url_fetcher)
         self.description = description
+        self.af_relationship = af_relationship
+
+        def epoch_to_pdf(epoch):
+            dt_object = datetime.datetime.fromtimestamp(epoch)
+            return datetime_to_pdf(dt_object)
+
+        def datetime_to_pdf(dt_object):
+            return dt_object.strftime("D:%Y%m%d%H%M%SZ")
+
+        if created:
+            self.created = created
+        else:
+            if filename:
+                self.created = epoch_to_pdf(os.path.getctime(filename))
+            else:
+                self.created = datetime_to_pdf(datetime.datetime.now())
+
+        if modified:
+            self.modified = modified
+        else:
+            if filename:
+                self.modified = epoch_to_pdf(os.path.getmtime(filename))
+            else:
+                self.modified = datetime_to_pdf(datetime.datetime.now())
 
 
 @contextlib.contextmanager

weasyprint/pdf/anchors.py

@@ -2,6 +2,7 @@
 
 import hashlib
 import io
+import mimetypes
 import zlib
 from os.path import basename
 from urllib.parse import unquote, urlsplit
@@ -270,12 +271,19 @@ def write_pdf_attachment(pdf, attachment, url_fetcher):
                 stream += compressed
             compressed = compress.flush(zlib.Z_FINISH)
             stream += compressed
+            mime_type, _ = mimetypes.guess_type(url, strict=False)
+            if not mime_type:
+                mime_type = 'application/octet-stream'
+            mime_type = '/' + mime_type.replace('/', '#2f')
             file_extra = pydyf.Dictionary({
                 'Type': '/EmbeddedFile',
                 'Filter': '/FlateDecode',
+                "Subtype": mime_type,
                 'Params': pydyf.Dictionary({
                     'CheckSum': f'<{md5.hexdigest()}>',
                     'Size': uncompressed_length,
+                    'CreationDate': attachment.created,
+                    'ModDate': attachment.modified,
                 })
             })
             file_stream = pydyf.Stream([stream], file_extra)
@@ -296,10 +304,14 @@ def write_pdf_attachment(pdf, attachment, url_fetcher):
         'Type': '/Filespec',
         'F': pydyf.String(),
         'UF': pydyf.String(filename),
+        "AFRelationship": "/Data",
         'EF': pydyf.Dictionary({'F': file_stream.reference}),
         'Desc': pydyf.String(attachment.description or ''),
     })
     pdf.add_object(attachment)
+    if "AF" not in pdf.catalog:
+        pdf.catalog["AF"] = pydyf.Array()
+    pdf.catalog["AF"].append(attachment.reference)
     return attachment