Proposed: Store presentation and book content via Lottie

Context and Problem Statement

[Safety brochure in Lottie format]

We want to display book content and presentation content in groups.

If the original content is in vectorized format, we want to keep it.

We do not have enterprise levels of engineering power.

Licenses have to be compatible with groups.

Describe the proposed option and how it helps to overcome the problem or limitation

Lottie via Samsung’s rlottie library helps solve this problem. Lottie keeps pixel and curve data.

RGBA8 data is big and Lottie keeps it as pixel and does not rasterize curves.

Lottie exports may turn fonts into curves.

V-Sekai already has the rlottie implementation in Godot engine so engineering effort is minimized.

rlottie is Groups license compatible.

Describe how your proposal will work, with code, pseudo-code, mock-ups, or diagrams

Offline export of lottie

  1. Install synfig-studio
  2. In synfig, for each page of pdf, epub, and others export a lottie json per page
  3. Ensure the documents are sorted correctly
  4. Save the folder as zstd compress 7zip archive
  5. Name the archive .cbzl This is file that is similar to CBZ but has an extra l to make it easy to identify as Lottie.

Online import of lottie

  1. Open the zip.
  2. For each sorted entry of the zip
  3. Make a Godot Engine PackedScene using the Groups Lottie importer.

Positive Consequences

  • In engine presentation engine

Negative Consequences

  • Lottie is an obscure format

Option graveyard:

  • Option: Create single executable Pdfium thing that writes to png

  • Rejection Reason:

  • Chromium build processes are difficult, but someone made a pdfium binary repository.

  • Option: Import pdfium into Godot Engine as a static library

  • Rejection Reason:

  • Adding pdf support to Godot Engine is difficult.

  • The straight-forward pdf implementation writes the RGBA8 data into the cache.

  • Option: Use Godot Engine’s native SVG library

  • Rejection Reason:

  • Does not support pixel data.

  • Unreliable

If this enhancement will not be used often, can it be worked around with a few lines of script?

rlottie and pdf formats are complicated.

Is there a reason why this should be core and done by us?

Presentations and books should be a first-class feature in groups.

References

  • https://www.synfig.org/
  • https://github.com/Samsung/rlottie
  • https://github.com/godot-extended-libraries/lottie
  • https://www.adobe.com/products/aftereffects.html
  • https://airbnb.io/lottie/#/
  • https://lottiefiles.com/
  • https://github.com/reMarkable/pdfium-binaries

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