Fixes #1045: Added super and subscript support with tests

src/pptx/oxml/text.py

@@ -26,6 +26,7 @@
     ST_TextTypeface,
     ST_TextWrappingType,
     XsdBoolean,
+    XsdInt,
 )
 from pptx.oxml.xmlchemy import (
     BaseOxmlElement,
@@ -325,6 +326,7 @@ class CT_TextCharacterProperties(BaseOxmlElement):
     u: MSO_TEXT_UNDERLINE_TYPE | None = OptionalAttribute(  # pyright: ignore[reportAssignmentType]
         "u", MSO_TEXT_UNDERLINE_TYPE
     )
+    baseline: int | None = OptionalAttribute("baseline", XsdInt) # pyright: ignore[reportAssignmentType]
 
     def _new_gradFill(self):
         return CT_GradientFillProperties.new_gradFill()

src/pptx/text/text.py

@@ -396,6 +396,69 @@ def size(self, emu: Length | None):
             sz = Emu(emu).centipoints
             self._rPr.sz = sz
 
+    @property
+    def superscript(self) -> int | None:
+        """
+        Return the superscript baseline offset if set, otherwise None.
+
+        A positive integer represents the text's upward shift relative to the baseline.
+        The default superscript offset is `30000` (when set via `True`).
+        """
+        if self._rPr.baseline and self._rPr.baseline > 0 :
+            return self._rPr.baseline
+        return None
+
+    @superscript.setter
+    def superscript(self, value: bool | int | None):
+        """
+        Set or remove superscript formatting.
+
+        - `True` sets the baseline to `30000` (default superscript offset).
+        - An `int` value explicitly sets the baseline to that amount.
+        - `False` or `None` removes superscript formatting.
+        """
+        if value is True:
+            self._rPr.baseline = 30000
+        elif value is False:
+            self._rPr.baseline = None
+        elif isinstance(value, int) and value >= 0:
+            self._rPr.baseline = value
+        else:
+            self._rPr.baseline = None
+
+    @property
+    def subscript(self) -> int | None:
+        """
+        Return the subscript baseline offset if set, otherwise None.
+
+        A negative integer represents the text's downward shift relative to the baseline.
+        The default subscript offset is `-15000` (when set via `True`).
+        """
+        if self._rPr.baseline and self._rPr.baseline < 0:
+            return self._rPr.baseline
+
+        return None
+
+    @subscript.setter
+    def subscript(self, value: bool | int | None):
+        """
+        Set or remove subscript formatting.
+
+        - `True` sets the baseline to `-15000` (default subscript offset).
+        - An `int` value explicitly sets the baseline to that amount.
+        - `False` or `None` removes subscript formatting.
+        """
+        if value is True:
+            self._rPr.baseline = -15000
+        elif value is False:
+            self._rPr.baseline = None
+        elif isinstance(value, int) and value <= 0:
+            self._rPr.baseline = value
+        else:
+            self._rPr.baseline = None
+
+
+
     @property
     def underline(self) -> bool | MSO_TEXT_UNDERLINE_TYPE | None:
         """Indicaties the underline setting for this font.

tests/text/test_text.py

@@ -498,6 +498,25 @@ def it_can_change_its_language_id_setting(self, language_id_set_fixture):
         font.language_id = new_value
         assert font._element.xml == expected_xml
 
+    def it_knows_its_superscript_setting(self, superscript_get_fixture):
+        font, expected_value = superscript_get_fixture
+        assert font.superscript == expected_value
+
+    def it_can_change_its_superscript_setting(self, superscript_set_fixture):
+        font, new_value, expected_xml = superscript_set_fixture
+        font.superscript = new_value
+        assert font._element.xml == expected_xml
+
+    def it_knows_its_subscript_setting(self, subscript_get_fixture):
+        font, expected_value = subscript_get_fixture
+        assert font.subscript == expected_value
+
+    def it_can_change_its_subscript_setting(self, subscript_set_fixture):
+        font, new_value, expected_xml = subscript_set_fixture
+        font.subscript = new_value
+        assert font._element.xml == expected_xml
+
+
     def it_knows_its_underline_setting(self, underline_get_fixture):
         font, expected_value = underline_get_fixture
         assert font.underline is expected_value, "got %s" % font.underline
@@ -636,6 +655,59 @@ def size_set_fixture(self, request):
         expected_xml = xml(expected_rPr_cxml)
         return font, new_value, expected_xml
 
+    @pytest.fixture(
+        params=[
+            ("a:rPr", None),  
+            ("a:rPr{baseline=30000}", 30000),  
+            ("a:rPr{baseline=15000}", 15000)  
+        ]
+    )
+    def superscript_get_fixture(self, request):
+        rPr_cxml, expected_value = request.param
+        font = Font(element(rPr_cxml))
+        return font, expected_value
+
+    @pytest.fixture(
+        params=[
+            ("a:rPr", True, "a:rPr{baseline=30000}"),
+            ("a:rPr", 20000, "a:rPr{baseline=20000}"),  
+            ("a:rPr{baseline=30000}", False, "a:rPr"),  
+            ("a:rPr{baseline=15000}", None, "a:rPr")  
+        ]
+    )
+    def superscript_set_fixture(self, request):
+        rPr_cxml, new_value, expected_rPr_cxml = request.param
+        font = Font(element(rPr_cxml))
+        expected_xml = xml(expected_rPr_cxml)
+        return font, new_value, expected_xml
+
+    @pytest.fixture(
+        params=[
+            ("a:rPr", None),  
+            ("a:rPr{baseline=-10000}", -10000),  
+            ("a:rPr{baseline=-15000}", -15000)  
+        ]
+    )
+    def subscript_get_fixture(self, request):
+        rPr_cxml, expected_value = request.param
+        font = Font(element(rPr_cxml))
+        return font, expected_value
+
+    @pytest.fixture(
+        params=[
+            ("a:rPr", True, "a:rPr{baseline=-15000}"),  
+            ("a:rPr", -10000, "a:rPr{baseline=-10000}"),
+            ("a:rPr", 10000, "a:rPr"), 
+            ("a:rPr{baseline=-10000}", False, "a:rPr"),  
+            ("a:rPr{baseline=-15000}", None, "a:rPr")  
+        ]
+    )
+    def subscript_set_fixture(self, request):
+        rPr_cxml, new_value, expected_rPr_cxml = request.param
+        font = Font(element(rPr_cxml))
+        expected_xml = xml(expected_rPr_cxml)
+        return font, new_value, expected_xml
+
     @pytest.fixture(
         params=[
             ("a:rPr", None),