DeckCraft integration for Nextcloud

Open and edit the files in your Nextcloud with DeckCraft, the open-source, Rust-native presentation app, without leaving the browser.

• Edit in DeckCraft appears in the Files action menu of every PowerPoint (.pptx, .potx, .ppsx) and DeckCraft (.deckcraft) presentation you can read.
• Save (Ctrl/⌘+S) stores the presentation in DeckCraft's own format: the first time, you pick the name and folder (it's offered next to the original), and later saves go to that file. File › Export › PowerPoint writes the .pptx back under its own name. Nextcloud keeps the previous state of a file as a version.
• Export (PDF, PNG, JPEG, outline) asks for a name and folder in your Nextcloud the first time.
• If someone else changes the file while you have it open, saving asks whether to replace their version or save a copy.
• Read-only files (for example a share without edit rights) open normally; saving offers a copy.
• Optionally, clicking a presentation in Files opens it in DeckCraft: tick Open presentations here from Files in the editor's top bar.

DeckCraft runs entirely in your browser as WebAssembly. Files go only between your browser and your Nextcloud; there is no extra server to run.

Requirements

• Nextcloud 33, 34 or 35
• A browser with WebGPU or WebGL2 (any current Chrome, Edge, Firefox or Safari)
• The web server must serve .wasm files as application/wasm. Nextcloud's own .htaccess does this on Apache; the recommended nginx configuration does too.
• Recommended: gzip or Brotli for application/wasm. DeckCraft is fetched once and then cached.

Install

Until the app is in the Nextcloud App Store, the latest version is in CyberFox-81/nextcloud_plugins, whose README has step-by-step commands for Docker, Nextcloud AIO and regular servers. In short:

1. Download integration_deckcraft.tar.gz and extract it into your Nextcloud's custom_apps/ (or apps/) folder, so you have custom_apps/integration_deckcraft/appinfo/info.xml.
2. Make it readable by the web server user, e.g. chown -R www-data:www-data custom_apps/integration_deckcraft.
3. Enable it: sudo -u www-data php occ app:enable integration_deckcraft. In Docker: docker exec -u www-data nextcloud php occ app:enable integration_deckcraft.

To make DeckCraft the click-to-open default for every user who hasn't chosen otherwise:

sudo -u www-data php occ config:app:set integration_deckcraft open_by_default --value=true --type=boolean

How it works

Files ── "Edit in DeckCraft" ──▶ /apps/integration_deckcraft/edit/{fileId}   (src/editor.ts)
                                  │  WebDAV GET/PUT with the user's session
                                  ▼
                                <iframe> /apps/integration_deckcraft/frame?host=parent   (templates/frame.php)
                                  │  DeckCraft (web/*.wasm) — postMessage bridge

The editor page downloads the file over WebDAV and passes it to DeckCraft with postMessage. When you save, DeckCraft passes the bytes back and the page uploads them with If-Match, so a newer version on the server is never overwritten without asking. A save in a format the opened file isn't in, and an export, ask for a name and folder with Nextcloud's own folder picker the first time; later saves under the same name go to the same file. The frame page is the only one whose Content Security Policy allows compiling WebAssembly.

DeckCraft's browser build saves by downloading a file. patches/deckcraft-nextcloud.patch adds an opt-in embedding bridge (?host=parent) to its web shell; the protocol is in web/README.md. It is meant to be proposed upstream, so a future official DeckCraft build can be used as is.

Build from source

make js      # npm ci && vite build → js/
make wasm    # clone DeckCraft, apply the patch, build → web/   (needs Rust, see below)
make dist    # → build/dist/integration_deckcraft-<version>.tar.gz

make wasm runs scripts/build-deckcraft-web.sh, which needs the wasm32-unknown-unknown Rust target, wasm-bindgen-cli at the version in DeckCraft's Cargo.lock (0.2.129 at the pinned commit), and optionally wasm-opt from binaryen. Set DECKCRAFT_REF to build another DeckCraft commit, FAST=1 for quicker development builds, and CRAFT_FONTS_DIR to a clone of storytold/craft-fonts to embed the shared Japanese fonts.

For development, npm run watch rebuilds the scripts as you edit; symlink or copy the repository into custom_apps/integration_deckcraft of a test server.

Releasing to the App Store

One-time setup (see the App Store developer guide):

1. Create the app's key and certificate request, and keep the key private and backed up:

   mkdir -p ~/.nextcloud/certificates && cd ~/.nextcloud/certificates
   openssl req -nodes -newkey rsa:4096 -keyout integration_deckcraft.key -out integration_deckcraft.csr -subj "/CN=integration_deckcraft"

2. Submit integration_deckcraft.csr as integration_deckcraft/integration_deckcraft.csr in a pull request to nextcloud/app-certificate-requests. Save the signed certificate they reply with as ~/.nextcloud/certificates/integration_deckcraft.crt.
3. Register the app at apps.nextcloud.com/developer/apps/new with the certificate and this signature:

   echo -n "integration_deckcraft" | openssl dgst -sha512 -sign ~/.nextcloud/certificates/integration_deckcraft.key | openssl base64

Each release:

make js && make wasm
scripts/sign-release.sh --key ~/.nextcloud/certificates/integration_deckcraft.key \
  --cert ~/.nextcloud/certificates/integration_deckcraft.crt --docker nextcloud

The script code-signs the app with occ integrity:sign-app (borrowed from a running Nextcloud container, or --occ for a local install; --archive signs a prebuilt archive), packs integration_deckcraft-<version>.tar.gz and prints the App Store signature. Attach the archive to a GitHub release, then submit its download URL and the signature at apps.nextcloud.com/developer/apps/releases/new.

Every new version also goes to nextcloud_plugins, replacing the previous one, with that repository's script (from a clone next to this one):

../nextcloud_plugins/scripts/update-plugin.py build/dist/integration_deckcraft-<version>.tar.gz

Limitations

• DeckCraft is young; see its roadmap for what's still missing.
• One person edits at a time. There is no live co-editing; concurrent saves are caught and you choose what happens.
• In the browser DeckCraft saves in its own format (.deckcraft); PowerPoint files are written with File › Export › PowerPoint.

License

This app is licensed under the AGPL-3.0-or-later. DeckCraft, bundled in web/, is licensed under MIT OR Apache-2.0; its bundled fonts and assets carry their own open licenses (see web/DECKCRAFT-ATTRIBUTION.md or web/DECKCRAFT-NOTICE). This is a community integration based on DeckCraft by the ArtCraft team, not made or endorsed by them.