From e51141d7ed735703bb07f5ffa7e5d2f4d9a79347 Mon Sep 17 00:00:00 2001
From: Martin Thoma <info@martin-thoma.de>
Date: Sun, 10 Jul 2022 15:53:04 +0200
Subject: [PATCH] ENH: Add PageObject._get_fonts (#1083)

Add possibility to get names of fonts

See #153

Co-authored-by: tiarno <jtim.arnold@gmail.com>
---
 PyPDF2/_page.py    | 45 +++++++++++++++++++++++++++++++++++++
 tests/test_page.py | 55 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 100 insertions(+)

diff --git a/PyPDF2/_page.py b/PyPDF2/_page.py
index 94cfb952c..0f0017241 100644
--- a/PyPDF2/_page.py
+++ b/PyPDF2/_page.py
@@ -39,6 +39,7 @@
     Iterator,
     List,
     Optional,
+    Set,
     Tuple,
     Union,
     cast,
@@ -1338,6 +1339,18 @@ def extractText(
         deprecate_with_replacement("extractText", "extract_text")
         return self.extract_text(Tj_sep=Tj_sep, TJ_sep=TJ_sep)
 
+    def _get_fonts(self) -> Tuple[Set[str], Set[str]]:
+        """
+        Get the names of embedded fonts and unembedded fonts.
+
+        :return: (Set of embedded fonts, set of unembedded fonts)
+        """
+        obj = self.get_object()
+        assert isinstance(obj, DictionaryObject)
+        fonts, embedded = _get_fonts_walk(cast(DictionaryObject, obj["/Resources"]))
+        unembedded = fonts - embedded
+        return embedded, unembedded
+
     mediabox = _create_rectangle_accessor(PG.MEDIABOX, ())
     """
     A :class:`RectangleObject<PyPDF2.generic.RectangleObject>`, expressed in default user space units,
@@ -1486,3 +1499,35 @@ def __getitem__(self, index: int) -> PageObject:
     def __iter__(self) -> Iterator[PageObject]:
         for i in range(len(self)):
             yield self[i]
+
+
+def _get_fonts_walk(
+    obj: DictionaryObject,
+    fnt: Optional[Set[str]] = None,
+    emb: Optional[Set[str]] = None,
+) -> Tuple[Set[str], Set[str]]:
+    """
+    If there is a key called 'BaseFont', that is a font that is used in the document.
+    If there is a key called 'FontName' and another key in the same dictionary object
+    that is called 'FontFilex' (where x is null, 2, or 3), then that fontname is
+    embedded.
+
+    We create and add to two sets, fnt = fonts used and emb = fonts embedded.
+    """
+    if fnt is None:
+        fnt = set()
+    if emb is None:
+        emb = set()
+    if not hasattr(obj, "keys"):
+        return set(), set()
+    fontkeys = ("/FontFile", "/FontFile2", "/FontFile3")
+    if "/BaseFont" in obj:
+        fnt.add(cast(str, obj["/BaseFont"]))
+    if "/FontName" in obj:
+        if [x for x in fontkeys if x in obj]:  # test to see if there is FontFile
+            emb.add(cast(str, obj["/FontName"]))
+
+    for key in obj.keys():
+        _get_fonts_walk(cast(DictionaryObject, obj[key]), fnt, emb)
+
+    return fnt, emb  # return the sets for each page
diff --git a/tests/test_page.py b/tests/test_page.py
index 987cf057a..65366459e 100644
--- a/tests/test_page.py
+++ b/tests/test_page.py
@@ -266,3 +266,58 @@ def test_extract_text_operator_t_star():  # L1266, L1267
     reader = PdfReader(BytesIO(get_pdf_from_url(url, name=name)))
     for page in reader.pages:
         page.extract_text()
+
+
+@pytest.mark.parametrize(
+    ("pdf_path", "password", "embedded", "unembedded"),
+    [
+        (
+            os.path.join(RESOURCE_ROOT, "crazyones.pdf"),
+            None,
+            {
+                "/HHXGQB+SFTI1440",
+                "/TITXYI+SFRM0900",
+                "/YISQAD+SFTI1200",
+            },
+            set(),
+        ),
+        (
+            os.path.join(RESOURCE_ROOT, "attachment.pdf"),
+            None,
+            {
+                "/HHXGQB+SFTI1440",
+                "/TITXYI+SFRM0900",
+                "/YISQAD+SFTI1200",
+            },
+            set(),
+        ),
+        (
+            os.path.join(RESOURCE_ROOT, "libreoffice-writer-password.pdf"),
+            "openpassword",
+            {"/BAAAAA+DejaVuSans"},
+            set(),
+        ),
+        (
+            os.path.join(RESOURCE_ROOT, "imagemagick-images.pdf"),
+            None,
+            set(),
+            {"/Helvetica"},
+        ),
+        (os.path.join(RESOURCE_ROOT, "imagemagick-lzw.pdf"), None, set(), set()),
+        (
+            os.path.join(RESOURCE_ROOT, "reportlab-inline-image.pdf"),
+            None,
+            set(),
+            {"/Helvetica"},
+        ),
+    ],
+)
+def test_get_fonts(pdf_path, password, embedded, unembedded):
+    reader = PdfReader(pdf_path, password=password)
+    a = set()
+    b = set()
+    for page in reader.pages:
+        a_tmp, b_tmp = page._get_fonts()
+        a = a.union(a_tmp)
+        b = b.union(b_tmp)
+    assert (a, b) == (embedded, unembedded)