add .tracking and px -> em conversion

arcade/text.py

@@ -613,6 +613,39 @@ def position(self, point: Point):
         else:
             self._label.position = x, y, self._label.z
 
+    @property
+    def tracking(self) -> float | None:
+        """
+        Get/set the tracking amount for this text object, or rather,
+        the added space between each character.
+
+        The value is an amount in pixels and can be negative.
+        To convert from the em unit, use Text.em_to_px().
+
+        Returns:
+            a pixel amount, or None if the tracking is inconsistent.
+        """
+        kerning = self._label.get_style("kerning")
+        return kerning if kerning != pyglet.text.document.STYLE_INDETERMINATE else None
+
+    @tracking.setter
+    def tracking(self, value: float):
+        self._label.set_style("kerning", value)
+
+    def em_to_px(self, em: float) -> float:
+        """Convert from an em value to a pixel amount.
+
+        1em is defined as ``font_size`` pt.
+        """
+        return (em * self.font_size) * (4 / 3)
+
+    def px_to_em(self, px: float) -> float:
+        """Convert from a pixel amount to a value in ems.
+
+        1em is defined as ``font_size`` pt.
+        """
+        return px / (4 / 3) / self.font_size
+
 
 def create_text_sprite(
     text: str,