feat(convert): PowerPoint conversion

docs/source/features_table.md

@@ -0,0 +1,25 @@
+# Features Table
+
+The following summarizes the different presentation features Manim Slides offers.
+
+:::{table} Comparison of the different presentation methods.
+:widths: auto
+:align: center
+
+| Feature / Constraint | [`present`](reference/cli.md) | [`convert --to=html`](reference/cli.md) | [`convert --to=pptx`](reference/cli.md) |
+| :--- | :---: | :---: | :---: |
+| Basic navigation through slides | Yes | Yes | Yes |
+| Replay slide | Yes | No | No |
+| Pause animation | Yes | No | No |
+| Play slide in reverse | Yes | No | No |
+| Needs Python with Manim Slides installed | Yes | No | No |
+| Requires internet access | No | Yes | No |
+| Auto. play slides | Yes | Yes | Yes |
+| Loops support | Yes | Yes | Yes |
+| Fully customizable | No | Yes (`--use-template` option) | No |
+| Other dependencies | None | A modern web browser | PowerPoint or LibreOffice Impress[^1]
+| Works cross-platforms | Yes | Yes | Partly[^1][^2] |
+:::
+
+[^1]: If you encounter a problem where slides do not automatically play or loops do not work, please [file an issue on GitHub](https://github.com/jeertmans/manim-slides/issues/new/choose).
+[^2]: PowerPoint online does not seem to support automatic playing of videos, so you need LibreOffice Impress on Linux platforms.

docs/source/index.md

@@ -39,6 +39,7 @@ Slide through the demo below to get a quick glimpse on what you can do with Mani
 
 quickstart
 reference/index
+features_table
 ```
 
 ```{toctree}

docs/source/reference/sharing.md

@@ -147,3 +147,17 @@ to know how to share your slide with GitHub pages, see the
 > **WARNING:** keep in mind that playing large video files over the internet
 can take some time, and *glitches* may occur between slide transitions for this
 reason.
+
+### With PowerPoint (*EXPERIMENTAL*)
+
+A recent conversion feature is to the PowerPoint format, thanks to the `python-pptx` package. Even though it is fully working, it is still considered in an *EXPERIMENTAL* status because we do not exactly know what versions of PowerPoint (or LibreOffice Impress) are supported.
+
+Basically, you can create a PowerPoint in a single command:
+
+```bash
+manim-slides convert --to=pptx BasicExample basic_example.pptx
+```
+
+All the videos and necessary files will be contained inside the `.pptx` file, so you can safely share it with anyone. By default, the `poster_frame_image`, i.e., what is displayed by PowerPoint when the video is not playing, is the first frame of each slide. This allows for smooth transitions.
+
+In the future, we hope to provide more features to this format, so feel free to suggest new features too!

manim_slides/convert.py

@@ -1,19 +1,37 @@
 import os
+import platform
+import subprocess
+import tempfile
 import webbrowser
 from enum import Enum
 from pathlib import Path
 from typing import Any, Callable, Dict, Generator, List, Optional, Type, Union
 
 import click
+import cv2
 import pkg_resources
+import pptx
 from click import Context, Parameter
-from pydantic import BaseModel, PositiveInt, ValidationError
+from lxml import etree
+from pydantic import BaseModel, FilePath, PositiveInt, ValidationError
+from tqdm import tqdm
 
 from .commons import folder_path_option, verbosity_option
 from .config import PresentationConfig
+from .logger import logger
 from .present import get_scenes_presentation_config
 
 
+def open_with_default(file: Path):
+    system = platform.system()
+    if system == "Darwin":
+        subprocess.call(("open", str(file)))
+    elif system == "Windows":
+        os.startfile(str(file))  # type: ignore[attr-defined]
+    else:
+        subprocess.call(("xdg-open", str(file)))
+
+
 def validate_config_option(
     ctx: Context, param: Parameter, value: Any
 ) -> Dict[str, str]:
@@ -55,6 +73,7 @@ def from_string(cls, s: str) -> Type["Converter"]:
         """Returns the appropriate converter from a string name."""
         return {
             "html": RevealJS,
+            "pptx": PowerPoint,
         }[s]
 
 
@@ -341,6 +360,90 @@ def convert_to(self, dest: Path) -> None:
             f.write(content)
 
 
+class PowerPoint(Converter):
+    left: PositiveInt = 0
+    top: PositiveInt = 0
+    width: PositiveInt = 1280
+    height: PositiveInt = 720
+    auto_play_media: bool = True
+    poster_frame_image: Optional[FilePath] = None
+
+    class Config:
+        use_enum_values = True
+        extra = "forbid"
+
+    def open(self, file: Path) -> bool:
+        return open_with_default(file)
+
+    def convert_to(self, dest: Path) -> None:
+        """Converts this configuration into a PowerPoint presentation, saved to DEST."""
+        prs = pptx.Presentation()
+        prs.slide_width = self.width * 9525
+        prs.slide_height = self.height * 9525
+
+        layout = prs.slide_layouts[6]  # Should be blank
+
+        # From GitHub issue comment:
+        # - https://github.com/scanny/python-pptx/issues/427#issuecomment-856724440
+        def auto_play_media(media: pptx.shape.picture.Movie, loop: bool = False):
+            el_id = xpath(media.element, ".//p:cNvPr")[0].attrib["id"]
+            el_cnt = xpath(
+                media.element.getparent().getparent().getparent(),
+                './/p:timing//p:video//p:spTgt[@spid="%s"]' % el_id,
+            )[0]
+            cond = xpath(el_cnt.getparent().getparent(), ".//p:cond")[0]
+            cond.set("delay", "0")
+
+            if loop:
+                ctn = xpath(el_cnt.getparent().getparent(), ".//p:cTn")[0]
+                ctn.set("repeatCount", "indefinite")
+
+        def xpath(el: etree.Element, query: str) -> etree.XPath:
+            nsmap = {"p": "http://schemas.openxmlformats.org/presentationml/2006/main"}
+            return etree.ElementBase.xpath(el, query, namespaces=nsmap)
+
+        def save_first_image_from_video_file(file: Path) -> Optional[str]:
+            cap = cv2.VideoCapture(str(file))
+            ret, frame = cap.read()
+
+            if ret:
+                f = tempfile.NamedTemporaryFile(mode="w", delete=False, suffix=".png")
+                cv2.imwrite(f.name, frame)
+                return f.name
+            else:
+                logger.warn("Failed to read first image from video file")
+                return None
+
+        for i, presentation_config in enumerate(self.presentation_configs):
+            presentation_config.concat_animations()
+            for slide_config in tqdm(
+                presentation_config.slides,
+                desc=f"Generating video slides for config {i + 1}",
+                leave=False,
+            ):
+                file = presentation_config.files[slide_config.start_animation]
+
+                if self.poster_frame_image is None:
+                    poster_frame_image = save_first_image_from_video_file(file)
+                else:
+                    poster_frame_image = str(self.poster_frame_image)
+
+                slide = prs.slides.add_slide(layout)
+                movie = slide.shapes.add_movie(
+                    str(file),
+                    self.left,
+                    self.top,
+                    self.width * 9525,
+                    self.height * 9525,
+                    poster_frame_image=poster_frame_image,
+                    mime_type="video/mp4",
+                )
+                if self.auto_play_media:
+                    auto_play_media(movie, loop=slide_config.is_loop())
+
+        prs.save(dest)
+
+
 def show_config_options(function: Callable[..., Any]) -> Callable[..., Any]:
     """Wraps a function to add a `--show-config` option."""
 
@@ -401,7 +504,7 @@ def callback(ctx: Context, param: Parameter, value: bool) -> None:
 @click.argument("dest", type=click.Path(dir_okay=False, path_type=Path))
 @click.option(
     "--to",
-    type=click.Choice(["html"], case_sensitive=False),
+    type=click.Choice(["html", "pptx"], case_sensitive=False),
     default="html",
     show_default=True,
     help="Set the conversion format to use.",