Add get_vertical_metrics and set_vertical_metrics methods. (#150)

README.md

@@ -67,6 +67,7 @@ with open("fonts/MyFont.ttf") as fh:
 -   [`get_variable_instance_by_style_name`](#get_variable_instance_by_style_name)
 -   [`get_variable_instance_closest_to_coordinates`](#get_variable_instance_closest_to_coordinates)
 -   [`get_version`](#get_version)
+-   [`get_vertical_metrics`](#get_vertical_metrics)
 -   [`get_weight`](#get_weight)
 -   [`get_width`](#get_width)
 -   [`is_static`](#is_static)
@@ -85,6 +86,7 @@ with open("fonts/MyFont.ttf") as fh:
 -   [`set_style_flags`](#set_style_flags)
 -   [`set_style_flags_by_subfamily_name`](#set_style_flags_by_subfamily_name)
 -   [`set_style_name`](#set_style_name)
+-   [`set_vertical_metrics`](#set_vertical_metrics)
 -   [`subset`](#subset)
 -   [`to_sliced_variable`](#to_sliced_variable)
 -   [`to_static`](#to_static)
@@ -519,6 +521,18 @@ Gets the font version.
 version = font.get_version()
 ```
 
+#### `get_vertical_metrics`
+```python
+"""
+Gets the font vertical metrics.
+
+:returns: A dictionary containing the following vertical metrics:
+    "ascent", "cap_height", "x_height", "descent", "descender"
+:rtype: dict
+"""
+metrics = font.get_vertical_metrics()
+```
+
 #### `get_weight`
 ```python
 """
@@ -785,6 +799,17 @@ Sets the style name updating the related font names records.
 font.set_style_name(name="Bold Italic")
 ```
 
+#### `set_vertical_metrics`
+```python
+"""
+Sets the vertical metrics.
+
+:param metrics: Keyword arguments representing the vertical metrics to set,
+    valid keys: "ascent", "cap_height", "x_height", "descent", "descender"
+"""
+font.set_vertical_metrics(ascent=1000, cap_height=750, x_height=500, descent=-250, descender=-500)
+```
+
 #### `subset`
 ```python
 """

fontbro/font.py

@@ -999,6 +999,26 @@ def get_version(self):
         version = head.fontRevision
         return version
 
+    def get_vertical_metrics(self):
+        """
+        Gets the font vertical metrics.
+
+        :returns: A dictionary containing the following vertical metrics:
+            "ascent", "cap_height", "x_height", "descent", "descender"
+        :rtype: dict
+        """
+        font = self.get_ttfont()
+        hhea = font.get("hhea")
+        os2 = font.get("OS/2")
+        metrics = {
+            "ascent": hhea.ascent if hhea else None,
+            "cap_height": os2.sCapHeight if os2 else None,
+            "x_height": os2.sxHeight if os2 else None,
+            "descent": hhea.descent if hhea else None,
+            "descender": os2.sTypoDescender if os2 else None,
+        }
+        return metrics
+
     def get_weight(self):
         """
         Gets the font weight value and name.
@@ -1494,6 +1514,32 @@ def set_style_name(self, name):
             style_name=name,
         )
 
+    def set_vertical_metrics(self, **metrics):
+        """
+        Sets the vertical metrics.
+
+        :param metrics: Keyword arguments representing the vertical metrics to set,
+            valid keys: "ascent", "cap_height", "x_height", "descent", "descender"
+        """
+        font = self.get_ttfont()
+        hhea = font.get("hhea")
+        os2 = font.get("OS/2")
+
+        if "ascent" in metrics:
+            hhea.ascent = metrics["ascent"]
+
+        if "cap_height" in metrics:
+            os2.sCapHeight = metrics["cap_height"]
+
+        if "x_height" in metrics:
+            os2.sxHeight = metrics["x_height"]
+
+        if "descent" in metrics:
+            hhea.descent = metrics["descent"]
+
+        if "descender" in metrics:
+            os2.sTypoDescender = metrics["descender"]
+
     def subset(self, *, unicodes="", glyphs=None, text="", **options):
         """
         Subsets the font using the given options (unicodes or glyphs or text),

tests/test_vertical_metrics.py

@@ -0,0 +1,39 @@
+from tests import AbstractTestCase
+
+
+class VerticalMetricsTestCase(AbstractTestCase):
+    """
+    Test case for the font vertical-metrics.
+    """
+
+    def test_get_vertical_metrics(self):
+        # font = self._get_font("/Roboto_Mono/static/RobotoMono-Regular.ttf")
+        # font = self._get_font("/Noto_Sans_TC/NotoSansTC-Regular.otf")
+        font = self._get_font("/Tourney/Tourney-VariableFont_wdth,wght.ttf")
+        vertical_metrics = font.get_vertical_metrics()
+        # print(vertical_metrics)
+        expected_vertical_metrics = {
+            "ascent": 1800,
+            "cap_height": 1400,
+            "x_height": 1080,
+            "descent": -400,
+            "descender": -400,
+        }
+        self.assertEqual(vertical_metrics, expected_vertical_metrics)
+
+    def test_set_vertical_metrics(self):
+        # font = self._get_font("/Roboto_Mono/static/RobotoMono-Regular.ttf")
+        # font = self._get_font("/Noto_Sans_TC/NotoSansTC-Regular.otf")
+        font = self._get_font("/Tourney/Tourney-VariableFont_wdth,wght.ttf")
+        vertical_metrics = {
+            "ascent": 1805,
+            "cap_height": 1405,
+            "x_height": 1085,
+            "descent": -405,
+            "descender": -405,
+        }
+        expected_vertical_metrics = vertical_metrics.copy()
+        font.set_vertical_metrics(**vertical_metrics)
+        vertical_metrics = font.get_vertical_metrics()
+        # print(vertical_metrics)
+        self.assertEqual(vertical_metrics, expected_vertical_metrics)