Fix unintended kwargs propagation in LaggedStartMap (#4613)

* Fix unintended kwargs propagation in LaggedStartMap

Ensure  intended for  are not forwarded to the superclass, and make  explicit.

* add test for keyword propagation in LaggedStartMap

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Update test_composition.py

update the test

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Update test_composition.py

add there_and_back

---------

Co-authored-by: Benjamin Hackl <mail@behackl.dev>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: 3 people

manim/animation/composition.py

@@ -353,7 +353,7 @@ class LaggedStartMap(LaggedStart):
 
     Parameters
     ----------
-    AnimationClass
+    animation_class
         :class:`~.Animation` to apply to mobject.
     mobject
         :class:`~.Mobject` whose submobjects the animation, and optionally the function,
@@ -362,6 +362,17 @@ class LaggedStartMap(LaggedStart):
         Function which will be applied to :class:`~.Mobject`.
     run_time
         The duration of the animation in seconds.
+    lag_ratio
+        Defines the delay after which the animation is applied to submobjects. A lag_ratio of
+        ``n.nn`` means the next animation will play when ``nnn%`` of the current animation has played.
+        Defaults to 0.05, meaning that the next animation will begin when 5% of the current
+        animation has played.
+
+        This does not influence the total runtime of the animation. Instead the runtime
+        of individual animations is adjusted so that the complete animation has the defined
+        run time.
+    kwargs
+        Further keyword arguments that are passed to `animation_class`.
 
     Examples
     --------
@@ -392,6 +403,7 @@ def __init__(
         mobject: Mobject,
         arg_creator: Callable[[Mobject], Iterable[Any]] | None = None,
         run_time: float = 2,
+        lag_ratio: float = DEFAULT_LAGGED_START_LAG_RATIO,
         **kwargs: Any,
     ):
         if arg_creator is None:
@@ -406,4 +418,4 @@ def identity(mob: Mobject) -> Mobject:
         if "lag_ratio" in anim_kwargs:
             anim_kwargs.pop("lag_ratio")
         animations = [animation_class(*args, **anim_kwargs) for args in args_list]
-        super().__init__(*animations, run_time=run_time, **kwargs)
+        super().__init__(*animations, run_time=run_time, lag_ratio=lag_ratio)

tests/module/animation/test_composition.py

@@ -5,14 +5,16 @@
 import pytest
 
 from manim.animation.animation import Animation, Wait
-from manim.animation.composition import AnimationGroup, Succession
+from manim.animation.composition import AnimationGroup, LaggedStartMap, Succession
 from manim.animation.creation import Create, Write
 from manim.animation.fading import FadeIn, FadeOut
 from manim.constants import DOWN, UP
 from manim.mobject.geometry.arc import Circle
 from manim.mobject.geometry.line import Line
 from manim.mobject.geometry.polygram import RegularPolygon, Square
+from manim.mobject.types.vectorized_mobject import VGroup
 from manim.scene.scene import Scene
+from manim.utils.rate_functions import linear, there_and_back
 
 
 def test_succession_timing():
@@ -189,6 +191,23 @@ def finish(self):
     assert circ_animation.finished
 
 
+def test_laggedstartmap_only_passes_kwargs_to_subanimations():
+    mobject = VGroup(Square(), Circle())
+    animation = LaggedStartMap(
+        FadeIn,
+        mobject,
+        rate_func=there_and_back,
+        lag_ratio=0.3,
+    )
+
+    assert animation.rate_func is linear
+    assert animation.lag_ratio == 0.3
+    assert all(
+        subanimation.rate_func is there_and_back
+        for subanimation in animation.animations
+    )
+
+
 def test_empty_animation_group_fails():
     with pytest.raises(ValueError, match="Please add at least one subanimation."):
         AnimationGroup().begin()