feat: DecimalNumber() - added spacing between values and unit (#3366)

* feat: DecimalNumber() - added spacing between values and unit

* Update manim/mobject/text/numbers.py

Co-authored-by: Benjamin Hackl <[email protected]>

* Update manim/mobject/text/numbers.py

Co-authored-by: Benjamin Hackl <[email protected]>

* Update manim/mobject/text/numbers.py

Co-authored-by: Benjamin Hackl <[email protected]>

* Update manim/mobject/text/numbers.py

Co-authored-by: Benjamin Hackl <[email protected]>

* Update manim/mobject/text/numbers.py

Co-authored-by: Benjamin Hackl <[email protected]>

* Update manim/mobject/text/numbers.py

Co-authored-by: Benjamin Hackl <[email protected]>

* Update manim/mobject/text/numbers.py

Co-authored-by: Benjamin Hackl <[email protected]>

---------

Co-authored-by: Tristan Schulz <[email protected]>
Co-authored-by: Benjamin Hackl <[email protected]>

manim/mobject/text/numbers.py

@@ -22,6 +22,34 @@
 class DecimalNumber(VMobject, metaclass=ConvertToOpenGL):
     """An mobject representing a decimal number.
 
+    Parameters
+    ----------
+    number
+        The numeric value to be displayed. It can later be modified using :meth:`.set_value`.
+    num_decimal_places
+        The number of decimal places after the decimal separator. Values are automatically rounded.
+    mob_class
+        The class for rendering digits and units, by default :class:`.MathTex`.
+    include_sign
+        Set to ``True`` to include a sign for positive numbers and zero.
+    group_with_commas
+        When ``True`` thousands groups are separated by commas for readability.
+    digit_buff_per_font_unit
+        Additional spacing between digits. Scales with font size.
+    show_ellipsis
+        When a number has been truncated by rounding, indicate with an ellipsis (``...``).
+    unit
+        A unit string which can be placed to the right of the numerical values.
+    unit_buff_per_font_unit
+        An additional spacing between the numerical values and the unit. A value
+        of ``unit_buff_per_font_unit=0.003`` gives a decent spacing. Scales with font size.
+    include_background_rectangle
+        Adds a background rectangle to increase contrast on busy scenes.
+    edge_to_fix
+        Assuring right- or left-alignment of the full object.
+    font_size
+        Size of the font.
+
     Examples
     --------
 
@@ -34,6 +62,8 @@ def construct(self):
                     show_ellipsis=True,
                     num_decimal_places=3,
                     include_sign=True,
+                    unit=r"\text{M-Units}",
+                    unit_buff_per_font_unit=0.003
                 )
                 square = Square().to_edge(UP)
 
@@ -59,6 +89,7 @@ def __init__(
         digit_buff_per_font_unit: float = 0.001,
         show_ellipsis: bool = False,
         unit: str | None = None,  # Aligned to bottom unless it starts with "^"
+        unit_buff_per_font_unit: float = 0,
         include_background_rectangle: bool = False,
         edge_to_fix: Sequence[float] = LEFT,
         font_size: float = DEFAULT_FONT_SIZE,
@@ -75,6 +106,7 @@ def __init__(
         self.digit_buff_per_font_unit = digit_buff_per_font_unit
         self.show_ellipsis = show_ellipsis
         self.unit = unit
+        self.unit_buff_per_font_unit = unit_buff_per_font_unit
         self.include_background_rectangle = include_background_rectangle
         self.edge_to_fix = edge_to_fix
         self._font_size = font_size
@@ -89,6 +121,7 @@ def __init__(
                 "digit_buff_per_font_unit": digit_buff_per_font_unit,
                 "show_ellipsis": show_ellipsis,
                 "unit": unit,
+                "unit_buff_per_font_unit": unit_buff_per_font_unit,
                 "include_background_rectangle": include_background_rectangle,
                 "edge_to_fix": edge_to_fix,
                 "font_size": font_size,
@@ -130,15 +163,25 @@ def _set_submobjects_from_number(self, number):
                 self._string_to_mob("\\dots", SingleStringMathTex, color=self.color),
             )
 
-        if self.unit is not None:
-            self.unit_sign = self._string_to_mob(self.unit, SingleStringMathTex)
-            self.add(self.unit_sign)
-
         self.arrange(
             buff=self.digit_buff_per_font_unit * self._font_size,
             aligned_edge=DOWN,
         )
 
+        if self.unit is not None:
+            self.unit_sign = self._string_to_mob(self.unit, SingleStringMathTex)
+            self.add(
+                self.unit_sign.next_to(
+                    self,
+                    direction=RIGHT,
+                    buff=(self.unit_buff_per_font_unit + self.digit_buff_per_font_unit)
+                    * self._font_size,
+                    aligned_edge=DOWN,
+                )
+            )
+
+        self.move_to(ORIGIN)
+
         # Handle alignment of parts that should be aligned
         # to the bottom
         for i, c in enumerate(num_string):