ENH: _writer: Add method to calculate text width

This adds a method to calculate the width of a text
string. This method can later be used to wrap text
at a certain length.

Author: PJBrs

pypdf/_writer.py

@@ -3408,6 +3408,30 @@ def _create_outline_item(
     return outline_item
 
 
+def calculate_text_width(character_widths: dict[str, int], font_size: float, txt: str) -> float:
+    """
+    Calculates the display width of a given text string in PDF user space units.
+
+    Args:
+        character_widths: A dictionary with font widths.
+        font_size: The font size in points
+        txt: A text string, the width of which you'd like to know
+
+    Returns:
+        The text string width in PDF user space units
+    """
+    total_font_units_width: float = 0
+
+    for char in txt:
+        try:
+            char_width = character_widths[char]
+        except KeyError:
+            char_width = character_widths.get("default", 0)
+        total_font_units_width += char_width
+
+    return (total_font_units_width * font_size) / 1000.0
+
+
 def generate_appearance_stream(
     txt: str,
     sel: list[str],