ENH: Font dataclass

This patch adds a new Font dataclass. Its initial use, for now,
is to act as a dataclass for the font metrics of the 14 Adobe
core fonts. These fonts are usually not embedded in PDF documents,
while PDF readers are expected to carry that information themselves.

Author: PJBrs

pypdf/_font.py

@@ -0,0 +1,19 @@
+from dataclasses import dataclass
+from typing import Dict, Tuple
+
+
+@dataclass(frozen=True)
+class Font:
+    name: str
+    family: str
+    weight: str
+
+    ascent: float
+    descent: float
+    cap_height: float
+    x_height: float
+    italic_angle: float
+    flags: int
+    bbox: Tuple[float, float, float, float]
+
+    character_widths: Dict[str, int]