feat(lib): add loop option to next_slide and remove `start/end_lo…

…op` (#294) * feat(lib): add `loop` option to `next_slide` and remove `start/end_loop` * fix(docs): PR number
jeertmans · Oct 19, 2023 · 0322dae · 0322dae
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -39,6 +39,9 @@ In an effort to better document changes, this CHANGELOG document is now created.
   [#285](https://github.com/jeertmans/manim-slides/pull/285)
 - Added a working `ThreeDSlide` class compatible with `manimlib`.
   [#285](https://github.com/jeertmans/manim-slides/pull/285)
+- Added `loop` option to `Slide`'s `next_slide` method.
+  Calling `next_slide` will never fail anymore.
+  [#294](https://github.com/jeertmans/manim-slides/pull/294)
 
 ### Changed
 
@@ -102,5 +105,9 @@ In an effort to better document changes, this CHANGELOG document is now created.
   [#243](https://github.com/jeertmans/manim-slides/pull/243)
 - Removed `PERF` verbosity level because not used anymore.
   [#245](https://github.com/jeertmans/manim-slides/pull/245)
+- Remove `Slide`'s method `start_loop` and `self.end_loop`
+  in favor to `self.next_slide(loop=True)`.
+  This is a **breaking change**.
+  [#294](https://github.com/jeertmans/manim-slides/pull/294)
 
 <!-- end changelog -->
diff --git a/README.md b/README.md
@@ -89,7 +89,9 @@ The documentation is available [online](https://eertmans.be/manim-slides/).
 
 ### Basic Example
 
-Wrap a series of animations between `self.start_loop()` and `self.stop_loop()` when you want to loop them (until input to continue):
+Call `self.next_slide()` everytime you want to create a pause between
+animations, and `self.next_slide(loop=True)` if you want the next slide to loop
+over animations until the user presses continue:
 
 ```python
 # example.py
@@ -107,9 +109,9 @@ class BasicExample(Slide):
         self.play(GrowFromCenter(circle))
         self.next_slide()  # Waits user to press continue to go to the next slide
 
-        self.start_loop()  # Start loop
+        self.next_slide(loop=True)  # Start loop
         self.play(MoveAlongPath(dot, circle), run_time=2, rate_func=linear)
-        self.end_loop()  # This will loop until user inputs a key
+        self.next_slide()  # This will start a new non-looping slide
 
         self.play(dot.animate.move_to(ORIGIN))
 ```

diff --git a/docs/source/reference/api.md b/docs/source/reference/api.md
@@ -14,11 +14,9 @@ use, not the methods used internally when rendering.
         add_to_canvas,
         canvas,
         canvas_mobjects,
-        end_loop,
         mobjects_without_canvas,
         next_slide,
         remove_from_canvas,
-        start_loop,
         wait_time_between_slides,
         wipe,
         zoom,

diff --git a/docs/source/reference/magic_example.ipynb b/docs/source/reference/magic_example.ipynb
@@ -58,10 +58,9 @@
     "        ).arrange(DOWN, buff=1.)\n",
     "        \n",
     "        self.play(Write(text))\n",
-    "        self.next_slide()\n",
-    "        self.start_loop()\n",
+    "        self.next_slide(loop=True)\n",
     "        self.play(Indicate(text[-1], scale_factor=2., run_time=.5))\n",
-    "        self.end_loop()\n",
+    "        self.next_slide()\n",
     "        self.play(FadeOut(text))"
    ]
   },

diff --git a/example.py b/example.py
@@ -16,11 +16,10 @@ def construct(self):
         dot = Dot()
 
         self.play(GrowFromCenter(circle))
-        self.next_slide()  # Waits user to press continue to go to the next slide
 
-        self.start_loop()  # Start loop
+        self.next_slide(loop=True)
         self.play(MoveAlongPath(dot, circle), run_time=2, rate_func=linear)
-        self.end_loop()  # This will loop until user inputs a key
+        self.next_slide()
 
         self.play(dot.animate.move_to(ORIGIN))
 
@@ -137,9 +136,9 @@ class Example(Slide):
     def construct(self):
         dot = Dot()
         self.add(dot)
-        self.start_loop()
+        self.next_slide(loop=True)
         self.play(Indicate(dot, scale_factor=2))
-        self.end_loop()
+        self.next_slide()
         square = Square()
         self.play(Transform(dot, square))
         self.next_slide()
@@ -195,17 +194,17 @@ def construct(self):
 
         watch_text = Text("Watch result on next slides!").shift(2 * DOWN).scale(0.5)
 
-        self.start_loop()
+        self.next_slide(loop=True)
         self.play(FadeIn(watch_text))
         self.play(FadeOut(watch_text))
-        self.end_loop()
+        self.next_slide()
         self.clear()
 
         dot = Dot()
         self.add(dot)
-        self.start_loop()
+        self.next_slide(loop=True)
         self.play(Indicate(dot, scale_factor=2))
-        self.end_loop()
+        self.next_slide()
         square = Square()
         self.play(Transform(dot, square))
         self.remove(dot)
@@ -245,9 +244,9 @@ def construct(self):
 
             self.next_slide()
 
-            self.start_loop()
+            self.next_slide(loop=True)
             self.play(MoveAlongPath(dot, circle), run_time=4, rate_func=linear)
-            self.end_loop()
+            self.next_slide()
 
             self.stop_ambient_camera_rotation()
             self.move_camera(phi=75 * DEGREES, theta=30 * DEGREES)
@@ -258,9 +257,9 @@ def construct(self):
             self.play(dot.animate.move_to(RIGHT * 3))
             self.next_slide()
 
-            self.start_loop()
+            self.next_slide(loop=True)
             self.play(MoveAlongPath(dot, circle), run_time=2, rate_func=linear)
-            self.end_loop()
+            self.next_slide()
 
             self.play(dot.animate.move_to(ORIGIN))
 
@@ -292,9 +291,9 @@ def updater(m, dt):
 
             self.next_slide()
 
-            self.start_loop()
+            self.next_slide(loop=True)
             self.play(MoveAlongPath(dot, circle), run_time=4, rate_func=linear)
-            self.end_loop()
+            self.next_slide()
 
             frame.remove_updater(updater)
             self.play(frame.animate.set_theta(30 * DEGREES))
@@ -304,9 +303,9 @@ def updater(m, dt):
             self.play(dot.animate.move_to(RIGHT * 3))
             self.next_slide()
 
-            self.start_loop()
+            self.next_slide(loop=True)
             self.play(MoveAlongPath(dot, circle), run_time=2, rate_func=linear)
-            self.end_loop()
+            self.next_slide()
 
             self.play(dot.animate.move_to(ORIGIN))
 

diff --git a/manim_slides/slide/base.py b/manim_slides/slide/base.py
@@ -29,10 +29,10 @@ def __init__(
         super().__init__(*args, **kwargs)
         self._output_folder: Path = output_folder
         self._slides: List[PreSlideConfig] = []
+        self._pre_slide_config_kwargs: MutableMapping[str, Any] = {}
         self._current_slide = 1
         self._current_animation = 0
-        self._loop_start_animation: Optional[int] = None
-        self._pause_start_animation = 0
+        self._start_animation = 0
         self._canvas: MutableMapping[str, Mobject] = {}
         self._wait_time_between_slides = 0.0
 
@@ -252,13 +252,16 @@ def play(self, *args: Any, **kwargs: Any) -> None:
         super().play(*args, **kwargs)  # type: ignore[misc]
         self._current_animation += 1
 
-    def next_slide(self) -> None:
+    def next_slide(self, loop: bool = False) -> None:
         """
-        Create a new slide with previous animations.
+        Create a new slide with previous animations, and setup options
+        for the next slide.
 
         This usually means that the user will need to press some key before the
         next slide is played. By default, this is the right arrow key.
 
+        :param loop:
+            If set, next slide will be looping.
 
         .. note::
 
@@ -267,7 +270,8 @@ def next_slide(self) -> None:
 
         .. warning::
 
-            This is not allowed to call :func:`next_slide` inside a loop.
+            When rendered with RevealJS, loops cannot be in the first nor
+            the last slide.
 
         Examples
         --------
@@ -290,58 +294,7 @@ def construct(self):
 
                     self.next_slide()
                     self.play(FadeOut(text))
-        """
-        assert (
-            self._loop_start_animation is None
-        ), "You cannot call `self.next_slide()` inside a loop"
-
-        if self.wait_time_between_slides > 0.0:
-            self.wait(self.wait_time_between_slides)  # type: ignore[attr-defined]
-
-        self._slides.append(
-            PreSlideConfig(
-                start_animation=self._pause_start_animation,
-                end_animation=self._current_animation,
-            )
-        )
-        self._current_slide += 1
-        self._pause_start_animation = self._current_animation
-
-    def _add_last_slide(self) -> None:
-        """Add a 'last' slide to the end of slides."""
-        if (
-            len(self._slides) > 0
-            and self._current_animation == self._slides[-1].end_animation
-        ):
-            return
-
-        self._slides.append(
-            PreSlideConfig(
-                start_animation=self._pause_start_animation,
-                end_animation=self._current_animation,
-                loop=self._loop_start_animation is not None,
-            )
-        )
-
-    def start_loop(self) -> None:
-        """
-        Start a loop. End it with :func:`end_loop`.
 
-        A loop will automatically replay the slide, i.e., everything between
-        :func:`start_loop` and :func:`end_loop`, upon reaching end.
-
-        .. warning::
-
-            You should always call :func:`next_slide` before calling this
-            method. Otherwise, ...
-
-        .. warning::
-
-            When rendered with RevealJS, loops cannot be in the first nor
-            the last slide.
-
-        Examples
-        --------
         The following contains one slide that will loop endlessly.
 
         .. manim-slides:: LoopExample
@@ -354,38 +307,46 @@ def construct(self):
                     dot = Dot(color=BLUE, radius=1)
 
                     self.play(FadeIn(dot))
-                    self.next_slide()
 
-                    self.start_loop()
+                    self.next_slide(loop=True)
 
                     self.play(Indicate(dot, scale_factor=2))
 
-                    self.end_loop()
+                    self.next_slide()
 
                     self.play(FadeOut(dot))
         """
-        assert self._loop_start_animation is None, "You cannot nest loops"
-        self._loop_start_animation = self._current_animation
+        if self._current_animation > self._start_animation:
+            if self.wait_time_between_slides > 0.0:
+                self.wait(self.wait_time_between_slides)  # type: ignore[attr-defined]
+
+            self._slides.append(
+                PreSlideConfig(
+                    start_animation=self._start_animation,
+                    end_animation=self._current_animation,
+                    **self._pre_slide_config_kwargs,
+                )
+            )
 
-    def end_loop(self) -> None:
-        """
-        End an existing loop.
+        self._pre_slide_config_kwargs = dict(loop=loop)
+        self._current_slide += 1
+        self._start_animation = self._current_animation
+
+    def _add_last_slide(self) -> None:
+        """Add a 'last' slide to the end of slides."""
+        if (
+            len(self._slides) > 0
+            and self._current_animation == self._slides[-1].end_animation
+        ):
+            return
 
-        See :func:`start_loop` for more details.
-        """
-        assert (
-            self._loop_start_animation is not None
-        ), "You have to start a loop before ending it"
         self._slides.append(
             PreSlideConfig(
-                start_animation=self._loop_start_animation,
+                start_animation=self._start_animation,
                 end_animation=self._current_animation,
-                loop=True,
+                **self._pre_slide_config_kwargs,
             )
         )
-        self._current_slide += 1
-        self._loop_start_animation = None
-        self._pause_start_animation = self._current_animation
 
     def _save_slides(self, use_cache: bool = True) -> None:
         """

diff --git a/manim_slides/slide/manim.py b/manim_slides/slide/manim.py
@@ -108,7 +108,7 @@ def construct(self):
 
                 bye = Text("Bye!")
 
-                self.start_loop()
+                self.next_slide(loop=True)
                 self.wipe(
                     self.mobjects_without_canvas,
                     [bye],
@@ -121,7 +121,7 @@ def construct(self):
                     direction=DOWN
                 )
                 self.wait(.5)
-                self.end_loop()
+                self.next_slide()
 
                 self.play(*[FadeOut(mobject) for mobject in self.mobjects])
     """

diff --git a/tests/data/slides.py b/tests/data/slides.py
@@ -26,12 +26,12 @@ def construct(self):
 
         self.play(FadeIn(square))
 
-        self.next_slide()
+        self.next_slide(loop=True)
 
-        self.start_loop()
         self.play(Rotate(square, +PI / 2))
         self.play(Rotate(square, -PI / 2))
-        self.end_loop()
+
+        self.next_slide()
 
         other_text = Text("Other text")
         self.wipe([square, circle], [other_text])