ENH: add capability to set font and size in fields

pypdf/_writer.py

@@ -780,7 +780,11 @@ def append_pages_from_reader(
                 after_page_append(writer_page)
 
     def _update_field_annotation(
-        self, field: DictionaryObject, anno: DictionaryObject
+        self,
+        field: DictionaryObject,
+        anno: DictionaryObject,
+        font_name: str = "",
+        font_size: float = -1,
     ) -> None:
         # Calculate rectangle dimensions
         _rct = cast(RectangleObject, anno[AA.Rect])
@@ -799,12 +803,22 @@ def _update_field_annotation(
             da = da.get_object()
         font_properties = da.replace("\n", " ").replace("\r", " ").split(" ")
         font_properties = [x for x in font_properties if x != ""]
-        font_name = font_properties[font_properties.index("Tf") - 2]
-        font_height = float(font_properties[font_properties.index("Tf") - 1])
+        if font_name:
+            font_properties[font_properties.index("Tf") - 2] = font_name
+        else:
+            font_name = font_properties[font_properties.index("Tf") - 2]
+        font_height = (
+            font_size
+            if font_size >= 0
+            else float(font_properties[font_properties.index("Tf") - 1])
+        )
         if font_height == 0:
-            font_height = rct.height - 2
-            font_properties[font_properties.index("Tf") - 1] = str(font_height)
-            da = " ".join(font_properties)
+            if field.get("/Ff", 0) & InteractiveFormDictEntries.Ff_Multiline:
+                font_height = 12
+            else:
+                font_height = rct.height - 2
+        font_properties[font_properties.index("Tf") - 1] = str(font_height)
+        da = " ".join(font_properties)
         y_offset = rct.height - 1 - font_height
 
         # Retrieve font information from local DR ...
@@ -944,11 +958,17 @@ def update_page_form_field_values(
                 annotations and field data will be updated.
                 `List[Pageobject]` - provides list of pages to be processed.
                 `None` - all pages.
-            fields: a Python dictionary of field names (/T) and text
-                values (/V).
-            flags: An integer (0 to 7). The first bit sets ReadOnly, the
-                second bit sets Required, the third bit sets NoExport. See
-                PDF Reference Table 8.70 for details.
+            fields: a Python dictionary of:
+
+                * field names (/T) as keys and  text values (/V) as value
+                * field names (/T) as keys and  list of text values (/V) for multiple choice list
+                * field names (/T) as keys and  tuple of :
+                    * text values (/V)
+                    * font id (e.g. /F1, the font id must exist)
+                    * font size (0 for autosize)
+            flags: An integer. You can build it with InteractiveFormDictEntries:
+            ex: InteractiveFormDictEntries.Ff_ReadOnly ^ InteractiveFormDictEntries.Ff_Multiline
+
             auto_regenerate: set/unset the need_appearances flag ;
                 the flag is unchanged if auto_regenerate is None.
         """
@@ -997,6 +1017,10 @@ def update_page_form_field_values(
                 if isinstance(value, list):
                     lst = ArrayObject(TextStringObject(v) for v in value)
                     writer_parent_annot[NameObject(FA.V)] = lst
+                elif isinstance(value, tuple):
+                    writer_annot[NameObject(FA.V)] = TextStringObject(
+                        value[0],
+                    )
                 else:
                     writer_parent_annot[NameObject(FA.V)] = TextStringObject(value)
                 if writer_parent_annot.get(FA.FT) in ("/Btn"):
@@ -1011,7 +1035,12 @@ def update_page_form_field_values(
                     or writer_parent_annot.get(FA.FT) == "/Ch"
                 ):
                     # textbox
-                    self._update_field_annotation(writer_parent_annot, writer_annot)
+                    if isinstance(value, tuple):
+                        self._update_field_annotation(
+                            writer_parent_annot, writer_annot, value[1], value[2]
+                        )
+                    else:
+                        self._update_field_annotation(writer_parent_annot, writer_annot)
                 elif (
                     writer_annot.get(FA.FT) == "/Sig"
                 ):  # deprecated  # not implemented yet

pypdf/constants.py

@@ -433,6 +433,31 @@ class InteractiveFormDictEntries:
     Q = "/Q"
     XFA = "/XFA"
 
+    # Common Field Flags
+    Ff_ReadOnly = 1
+    Ff_Required = 2
+    Ff_NoExport = 4
+    # Text Field Flags
+    Ff_Multiline = 1 << (13 - 1)
+    Ff_Password = 1 << (14 - 1)
+    Ff_FileSelect = 1 << (21 - 1)
+    Ff_DoNotSpellCheck = 1 << (23 - 1)
+    Ff_DoNotScroll = 1 << (24 - 1)
+    Ff_Comb = 1 << (25 - 1)
+    Ff_RichText = 1 << (26 - 1)
+    # Button Field Flags
+    Ff_NoToggleToOff = 1 << (15 - 1)
+    Ff_Radio = 1 << (16 - 1)
+    Ff_Pushbutton = 1 << (17 - 1)
+    Ff_RadiosInUnison = 1 << (26 - 1)
+    # Choice Field FlagsZ
+    Ff_Combo = 1 << (18 - 1)
+    Ff_Edit = 1 << (19 - 1)
+    Ff_Sort = 1 << (20 - 1)
+    Ff_MultiSelect = 1 << (22 - 1)
+    # Ff_DoNotSpellCheck
+    Ff_CommitOnSelChange = 1 << (27 - 1)
+
 
 class FieldDictionaryAttributes:
     """Table 8.69 Entries common to all field dictionaries (PDF 1.7 reference)."""

tests/test_writer.py

@@ -2230,3 +2230,26 @@ def test_i_in_choice_fields():
         writer.pages[0], {"State": "NY"}, auto_regenerate=False
     )
     assert "/I" not in writer.get_fields()["State"].indirect_reference.get_object()
+
+
+def test_selfont():
+    writer = PdfWriter(clone_from=RESOURCE_ROOT / "FormTestFromOo.pdf")
+    writer.update_page_form_field_values(
+        writer.pages[0],
+        {"Text1": ("Text_1", "", 5), "Text2": ("Text_2", "/F3", 0)},
+        auto_regenerate=False,
+    )
+    assert (
+        b"/F3 5 Tf"
+        in writer.pages[0]["/Annots"][1].get_object()["/AP"]["/N"].get_data()
+    )
+    assert (
+        b"Text_1" in writer.pages[0]["/Annots"][1].get_object()["/AP"]["/N"].get_data()
+    )
+    assert (
+        b"/F3 12 Tf"
+        in writer.pages[0]["/Annots"][2].get_object()["/AP"]["/N"].get_data()
+    )
+    assert (
+        b"Text_2" in writer.pages[0]["/Annots"][2].get_object()["/AP"]["/N"].get_data()
+    )