feat(lib): add auto_next option (#304)

* feat(lib): add `auto_next` option

As suggested in #302, you can now automatically skip a slide. It works both with `present` and `convert --to=html`!

Closes #302

* chore(ci): add trigger on push on main

.github/workflows/tests.yml

@@ -1,4 +1,7 @@
 on:
+  push:
+    branches:
+    - main
   pull_request:
   workflow_dispatch:
 

CHANGELOG.md

@@ -48,6 +48,10 @@ In an effort to better document changes, this CHANGELOG document is now created.
   [#295](https://github.com/jeertmans/manim-slides/pull/295)
 - Added `--playback-rate` option to `manim-slides present` for testing purposes.
   [#300](https://github.com/jeertmans/manim-slides/pull/300)
+- Added `auto_next` option to `Slide`'s `next_slide` method to automatically
+  play the next slide upon terminating. Supported by `present` and
+  `convert --to=html` commands.
+  [#304](https://github.com/jeertmans/manim-slides/pull/304)
 
 (v5-changed)=
 ### Changed

example.py

@@ -185,12 +185,11 @@ class Example(Slide):
 
         self.play(Transform(step, step_5))
         self.play(Transform(code, code_step_5))
-        self.next_slide()
+        self.next_slide(auto_next=True)
 
         self.play(Transform(step, step_6))
         self.play(Transform(code, code_step_6))
         self.play(code.animate.shift(UP), FadeIn(code_step_7), FadeIn(or_text))
-        self.next_slide()
 
         watch_text = Text("Watch result on next slides!").shift(2 * DOWN).scale(0.5)
 

manim_slides/config.py

@@ -139,6 +139,7 @@ class PreSlideConfig(BaseModel):  # type: ignore
     start_animation: int
     end_animation: int
     loop: bool = False
+    auto_next: bool = False
 
     @field_validator("start_animation", "end_animation")
     @classmethod
@@ -164,6 +165,21 @@ class PreSlideConfig(BaseModel):  # type: ignore
 
         return pre_slide_config
 
+    @model_validator(mode="after")
+    @classmethod
+    def loop_and_auto_next_disallowed(
+        cls, pre_slide_config: "PreSlideConfig"
+    ) -> "PreSlideConfig":
+        if pre_slide_config.loop and pre_slide_config.auto_next:
+            raise ValueError(
+                "You cannot have both `loop=True` and `auto_next=True`, "
+                "because a looping slide has no ending. "
+                "This may be supported in the future if "
+                "https://github.com/jeertmans/manim-slides/pull/299 gets merged."
+            )
+
+        return pre_slide_config
+
     @property
     def slides_slice(self) -> slice:
         return slice(self.start_animation, self.end_animation)
@@ -173,12 +189,18 @@ class SlideConfig(BaseModel):  # type: ignore[misc]
     file: FilePath
     rev_file: FilePath
     loop: bool = False
+    auto_next: bool = False
 
     @classmethod
     def from_pre_slide_config_and_files(
         cls, pre_slide_config: PreSlideConfig, file: Path, rev_file: Path
     ) -> "SlideConfig":
-        return cls(file=file, rev_file=rev_file, loop=pre_slide_config.loop)
+        return cls(
+            file=file,
+            rev_file=rev_file,
+            loop=pre_slide_config.loop,
+            auto_next=pre_slide_config.auto_next,
+        )
 
 
 class PresentationConfig(BaseModel):  # type: ignore[misc]

manim_slides/convert.py

@@ -61,7 +61,9 @@ def validate_config_option(
             config[key] = value
         except ValueError:
             raise click.BadParameter(
-                f"Configuration options `{c_option}` could not be parsed into a proper (key, value) pair. Please use an `=` sign to separate key from value."
+                f"Configuration options `{c_option}` could not be parsed into "
+                "a proper (key, value) pair. "
+                "Please use an `=` sign to separate key from value."
             ) from None
 
     return config
@@ -75,6 +77,15 @@ def file_to_data_uri(file: Path) -> str:
     return f"data:{mime_type};base64,{b64}"
 
 
+def get_duration_ms(file: Path) -> float:
+    """Read a video and return its duration in milliseconds."""
+    cap = cv2.VideoCapture(str(file))
+    fps: int = cap.get(cv2.CAP_PROP_FPS)
+    frame_count: int = cap.get(cv2.CAP_PROP_FRAME_COUNT)
+
+    return 1000 * frame_count / fps
+
+
 class Converter(BaseModel):  # type: ignore
     presentation_configs: conlist(PresentationConfig, min_length=1)  # type: ignore[valid-type]
     assets_dir: str = "{basename}_assets"
@@ -396,7 +407,9 @@ class RevealJS(Converter):
             options["assets_dir"] = assets_dir
 
             content = revealjs_template.render(
-                file_to_data_uri=file_to_data_uri, **options
+                file_to_data_uri=file_to_data_uri,
+                get_duration_ms=get_duration_ms,
+                **options,
             )
 
             f.write(content)

manim_slides/present/player.py

@@ -137,6 +137,17 @@ class Player(QMainWindow):  # type: ignore[misc]
 
             self.media_player.mediaStatusChanged.connect(media_status_changed)
 
+        else:
+
+            def media_status_changed(status: QMediaPlayer.MediaStatus) -> None:
+                if (
+                    status == QMediaPlayer.EndOfMedia
+                    and self.current_slide_config.auto_next
+                ):
+                    self.load_next_slide()
+
+            self.media_player.mediaStatusChanged.connect(media_status_changed)
+
         if self.current_slide_config.loop:
             self.media_player.setLoops(-1)
 

manim_slides/slide/base.py

@@ -252,7 +252,9 @@ class BaseSlide:
         super().play(*args, **kwargs)  # type: ignore[misc]
         self._current_animation += 1
 
-    def next_slide(self, *, loop: bool = False, **kwargs: Any) -> None:
+    def next_slide(
+        self, *, loop: bool = False, auto_next: bool = False, **kwargs: Any
+    ) -> None:
         """
         Create a new slide with previous animations, and setup options
         for the next slide.
@@ -266,6 +268,12 @@ class BaseSlide:
             or ignored if `manimlib` API is used.
         :param loop:
             If set, next slide will be looping.
+        :param auto_next:
+            If set, next slide will play immediately play the next slide
+            upon terminating.
+
+            Note that this is only supported by ``manim-slides present``
+            and ``manim-slides convert --to=html``.
         :param kwargs:
             Keyword arguments to be passed to
             :meth:`Scene.next_section<manim.scene.scene.Scene.next_section>`,
@@ -328,6 +336,28 @@ class BaseSlide:
                     self.next_slide()
 
                     self.play(FadeOut(dot))
+
+        The following contains one slide that triggers the next slide
+        upon terminating.
+
+        .. manim-slides:: AutoNextExample
+
+            from manim import *
+            from manim_slides import Slide
+
+            class AutoNextExample(Slide):
+                def construct(self):
+                    square = Square(color=RED, side_length=2)
+
+                    self.play(GrowFromCenter(square))
+
+                    self.next_slide(auto_next=True)
+
+                    self.play(Wiggle(square))
+
+                    self.next_slide()
+
+                    self.wipe(square)
         """
         if self._current_animation > self._start_animation:
             if self.wait_time_between_slides > 0.0:
@@ -343,7 +373,7 @@ class BaseSlide:
 
             self._current_slide += 1
 
-        self._pre_slide_config_kwargs = dict(loop=loop)
+        self._pre_slide_config_kwargs = dict(loop=loop, auto_next=auto_next)
         self._start_animation = self._current_animation
 
     def _add_last_slide(self) -> None:

manim_slides/slide/manim.py

@@ -79,9 +79,11 @@ class Slide(BaseSlide, Scene):  # type: ignore[misc]
         """
         self.next_slide(*args, **kwargs)
 
-    def next_slide(self, *args: Any, loop: bool = False, **kwargs: Any) -> None:
+    def next_slide(
+        self, *args: Any, loop: bool = False, auto_next: bool = False, **kwargs: Any
+    ) -> None:
         Scene.next_section(self, *args, **kwargs)
-        BaseSlide.next_slide(self, loop=loop)
+        BaseSlide.next_slide(self, loop=loop, auto_next=auto_next)
 
     def render(self, *args: Any, **kwargs: Any) -> None:
         """MANIM render."""

manim_slides/templates/revealjs.html

@@ -36,6 +36,9 @@
               {%- endif -%}
               {% if slide_config.loop -%}
                 data-background-video-loop
+              {%- endif -%}
+              {% if slide_config.auto_next -%}
+                data-autoslide="{{ get_duration_ms(slide_config.file) }}"
               {%- endif -%}>
             </section>
           {%- endfor -%}

tests/conftest.py

@@ -38,6 +38,16 @@ def manimgl_config(project_folder: Path) -> Iterator[Path]:
     yield (project_folder / "custom_config.yml").resolve(strict=True)
 
 
+@pytest.fixture(scope="session")
+def video_file(data_folder: Path) -> Iterator[Path]:
+    yield (data_folder / "video.mp4").resolve(strict=True)
+
+
+@pytest.fixture(scope="session")
+def video_data_uri_file(data_folder: Path) -> Iterator[Path]:
+    yield (data_folder / "video_data_uri.txt").resolve(strict=True)
+
+
 def random_path(
     length: int = 20,
     dirname: Path = Path("./media/videos/example"),

tests/test_convert.py

@@ -31,9 +31,19 @@ from manim_slides.convert import (
     SlideNumber,
     Transition,
     TransitionSpeed,
+    file_to_data_uri,
+    get_duration_ms,
 )
 
 
+def test_get_duration_ms(video_file: Path) -> None:
+    assert get_duration_ms(video_file) == 2000.0
+
+
+def test_file_to_data_uri(video_file: Path, video_data_uri_file: Path) -> None:
+    assert file_to_data_uri(video_file) == video_data_uri_file.read_text().strip()
+
+
 @pytest.mark.parametrize(
     ("enum_type",),
     [

tests/test_slide.py

@@ -21,6 +21,7 @@ from manim import (
     Text,
 )
 from manim.__main__ import main as manim_cli
+from pydantic import ValidationError
 
 from manim_slides.config import PresentationConfig
 from manim_slides.defaults import FOLDER_PATH
@@ -165,6 +166,37 @@ class TestSlide:
 
             assert not self._pre_slide_config_kwargs["loop"]
 
+    @assert_constructs
+    class TestAutoNext(Slide):
+        def construct(self) -> None:
+            text = Text("Some text")
+
+            self.add(text)
+
+            assert "auto_next" not in self._pre_slide_config_kwargs
+
+            self.next_slide(auto_next=True)
+            self.play(text.animate.scale(2))
+
+            assert self._pre_slide_config_kwargs["auto_next"]
+
+            self.next_slide(auto_next=False)
+
+            assert not self._pre_slide_config_kwargs["auto_next"]
+
+    @assert_constructs
+    class TestLoopAndAutoNextFails(Slide):
+        def construct(self) -> None:
+            text = Text("Some text")
+
+            self.add(text)
+
+            self.next_slide(loop=True, auto_next=True)
+            self.play(text.animate.scale(2))
+
+            with pytest.raises(ValidationError):
+                self.next_slide()
+
     @assert_constructs
     class TestWipe(Slide):
         def construct(self) -> None: