Two New Classes in geometry module: :class:.LabeledLine and :class:.LabeledArrow

manim/__init__.py

@@ -46,6 +46,7 @@
 from .mobject.frame import *
 from .mobject.geometry.arc import *
 from .mobject.geometry.boolean_ops import *
+from .mobject.geometry.labeled import *
 from .mobject.geometry.line import *
 from .mobject.geometry.polygram import *
 from .mobject.geometry.shape_matchers import *

manim/mobject/geometry/__init__.py

@@ -8,6 +8,7 @@
 
     ~arc
     ~boolean_ops
+    ~labeled
     ~line
     ~polygram
     ~shape_matchers

manim/mobject/geometry/labeled.py

@@ -0,0 +1,153 @@
+r"""Mobjects that inherit from lines and contain a label along the length."""
+
+from __future__ import annotations
+
+__all__ = ["LabeledLine", "LabeledArrow"]
+
+from manim.constants import *
+from manim.mobject.geometry.line import Arrow, Line
+from manim.mobject.geometry.shape_matchers import (
+    BackgroundRectangle,
+    SurroundingRectangle,
+)
+from manim.mobject.text.tex_mobject import MathTex, Tex
+from manim.mobject.text.text_mobject import Text
+from manim.utils.color import WHITE, Color
+
+
+class LabeledLine(Line):
+    """Constructs a line containing a label box somewhere along its length.
+
+    Parameters
+    ----------
+    label : str | Tex | MathTex | Text
+        Label that will be displayed on the line.
+    label_position : float | optional
+        A ratio in the range [0-1] to indicate the position of the label with respect to the length of the line. Default value is 0.5.
+    font_size : float | optional
+        Control font size for the label. This parameter is only used when `label` is of type `str`.
+    label_color: numpy.ndarray | optional
+        The color of the label's text. This parameter is only used when `label` is of type `str`.
+    label_frame : Bool | optional
+        Add a `SurroundingRectangle` frame to the label box.
+    frame_fill_color : numpy.ndarray | optional
+        Background color to fill the label box. If no value is provided, the background color of the canvas will be used.
+    frame_fill_opacity : float | optional
+        Determine the opacity of the label box by passing a value in the range [0-1], where 0 indicates complete transparency and 1 means full opacity.
+
+    .. seealso::
+        :class:`LabeledArrow`
+
+    Examples
+    --------
+    .. manim:: LabeledLineExample
+        :save_last_frame:
+
+        class LabeledLineExample(Scene):
+            def construct(self):
+                line = LabeledLine(
+                    label          = '0.5',
+                    label_position = 0.8,
+                    font_size      = 20,
+                    label_color    = WHITE,
+                    label_frame    = True,
+
+                    start=LEFT+DOWN,
+                    end=RIGHT+UP)
+
+
+                line.set_length(line.get_length() * 2)
+                self.add(line)
+    """
+
+    def __init__(
+        self,
+        label: str | Tex | MathTex | Text,
+        label_position: float = 0.5,
+        font_size: float = DEFAULT_FONT_SIZE,
+        label_color: Color | str | None = WHITE,
+        label_frame: bool = True,
+        frame_fill_color: Color | str | None = None,
+        frame_fill_opacity: float = 1,
+        *args,
+        **kwargs,
+    ) -> None:
+        if isinstance(label, str):
+            from manim import MathTex
+
+            rendered_label = MathTex(label, color=label_color, font_size=font_size)
+        else:
+            rendered_label = label
+
+        super().__init__(*args, **kwargs)
+
+        # calculating the vector for the label position
+        line_start, line_end = self.get_start_and_end()
+        new_vec = (line_end - line_start) * label_position
+        label_coords = line_start + new_vec
+
+        # rendered_label.move_to(self.get_vector() * label_position)
+        rendered_label.move_to(label_coords)
+
+        box = BackgroundRectangle(
+            rendered_label,
+            buff=0.05,
+            color=frame_fill_color,
+            fill_opacity=frame_fill_opacity,
+            stroke_width=0.5,
+        )
+        self.add(box)
+
+        if label_frame:
+            box_frame = SurroundingRectangle(
+                rendered_label, buff=0.05, color=label_color, stroke_width=0.5
+            )
+
+            self.add(box_frame)
+
+        self.add(rendered_label)
+
+
+class LabeledArrow(LabeledLine, Arrow):
+    """Constructs an arrow containing a label box somewhere along its length.
+    This class inherits its label properties from `LabeledLine`, so the main parameters controlling it are the same.
+
+    Parameters
+    ----------
+    label : str | Tex | MathTex | Text
+        Label that will be displayed on the line.
+    label_position : float | optional
+        A ratio in the range [0-1] to indicate the position of the label with respect to the length of the line. Default value is 0.5.
+    font_size : float | optional
+        Control font size for the label. This parameter is only used when `label` is of type `str`.
+    label_color: numpy.ndarray | optional
+        The color of the label's text. This parameter is only used when `label` is of type `str`.
+    label_frame : Bool | optional
+        Add a `SurroundingRectangle` frame to the label box.
+    frame_fill_color : numpy.ndarray | optional
+        Background color to fill the label box. If no value is provided, the background color of the canvas will be used.
+    frame_fill_opacity : float | optional
+        Determine the opacity of the label box by passing a value in the range [0-1], where 0 indicates complete transparency and 1 means full opacity.
+
+
+    .. seealso::
+        :class:`LabeledLine`
+
+    Examples
+    --------
+    .. manim:: LabeledArrowExample
+        :save_last_frame:
+
+        class LabeledArrowExample(Scene):
+            def construct(self):
+                l_arrow = LabeledArrow("0.5", start=LEFT*3, end=RIGHT*3 + UP*2, label_position=0.5)
+
+                self.add(l_arrow)
+    """
+
+    def __init__(
+        self,
+        *args,
+        **kwargs,
+    ) -> None:
+        super().__init__(*args, **kwargs)

tests/test_graphical_units/test_geometry.py

@@ -247,3 +247,25 @@ def test_CurvedArrowCustomTip(scene):
         tip_shape_end=ArrowSquareFilledTip,
     )
     scene.add(arrow, double_arrow)
+
+
+@frames_comparison
+def test_LabeledLine(scene):
+    line = LabeledLine(
+        label="0.5",
+        label_position=0.8,
+        font_size=20,
+        label_color=WHITE,
+        label_frame=True,
+        start=LEFT + DOWN,
+        end=RIGHT + UP,
+    )
+    scene.add(line)
+
+
+@frames_comparison
+def test_LabeledArrow(scene):
+    l_arrow = LabeledArrow(
+        "0.5", start=LEFT * 3, end=RIGHT * 3 + UP * 2, label_position=0.5, font_size=15
+    )
+    scene.add(l_arrow)