Open Canvas (OCIF)

Dev-Centr endorses the Open Canvas Interchange Format (OCIF) from the Open Canvas Working Group as the preferred edit + interchange format for infinite-canvas and sticky-board documents.

Status (as of endorsement)

Candidate Recommendation (implementation feedback). Spec site: spec.canvasprotocol.org. MIME type commonly application/vnd.ocif+json; extension often .ocif.json / .ocif.

Why not SVG as the live document?

SVG is an excellent render and export target (browsers, Inkscape, print pipelines). It is a poor primary app document for sticky notes and freeform boards:

  • Coordinate framing (viewBox, units, CSS) fights infinite-canvas mental models.

  • Text is not a first-class editable note object; sticky / group / arrow semantics are app inventions layered on paths and groups.

  • Editors that stay productive on SVG usually keep non-standard editor state in namespaces (Inkscape SVG) or abandon SVG as the native store entirely (Affinity .afdesign, Illustrator .ai).

Inkscape is not replacing SVG. Native save remains SVG-with-Inkscape extensions; Plain SVG is the stripped interchange export. Historical chatter about a proprietary .ink was rejected because Inkscape’s identity is “standards-compliant SVG editor.” If you heard “move away from SVG for the live document,” that is the category of problem Affinity/Illustrator solve with proprietary natives — not an Inkscape press plan to dump SVG.

What OCIF is for

OCIF is a JSON scene graph aimed at canvas apps talking to each other:

  • Nodes — placed visual items (position, size, optional parent/scale).

  • Relations — edges, groups, hyperedges.

  • Resources — text, SVG snippets, rasters, other blobs referenced by nodes.

Coordinate system matches common 2D APIs (origin top-left, +y down). Extensions (namespaced) carry product-specific shapes (e.g. sticky notes) without forking the core file.

Reference implementations include tldraw’s OCIF plugin (v0.7.0 at endorsement time). Prefer OCIF over copying any one product’s private JSON (Excalidraw/tldraw store dumps) as a long-term house format.

Dev-Centr document kind mapping

Keep prose, plain buffers, and canvas scenes as distinct kinds — do not force one encoding to fake the others.

Kind Preferred on-disk Notes

Plain (raw text / code)

.txt or extensionless UTF-8

User-visible encoding and EOL. Default for “just a note.” Markup assist optional; not silent rich promotion.

Doc (flow rich text)

CentrMark (.cmk)

Human-authored structured prose. See CentrMark docs; do not confuse with structured data formats (Structured data formats).

Canvas (board / sticky / diagram)

OCIF

Edit + interchange. Export SVG (and raster) for picture pipelines. Do not treat SVG as the only store.
Optional composition

a CentrMark doc may embed or link an OCIF resource (diagram-as-attachment). Prefer a standalone .ocif when the note is the board.

Implementation posture (D and owned apps)

  • No maintained OCIF package on DUB at endorsement time (dub search ocif empty). Prefer a first-party D reimplementation of a pinned OCIF version (start at v0.7.0) over wrapping Node/JS runtimes into desktop processes.

  • Pin the spec version in the library; bump deliberately when OCWG ships breaking revisions (CR still gathers implementer feedback — expect churn at the edges, not weekly rewrite of core nodes).

  • Publish the D library to code.dlang.org when it parses/serializes a useful subset (rect, oval, path, text resource, arrow) so Notorious and other Dev-Centr tools share one codec.

  • Product apps (e.g. Notorious) map UI tools ↔ OCIF nodes; keep an in-memory editor model for hit-testing and undo — that model is not “in-memory JSON as source of truth.” On disk, OCIF (or Plain / CentrMark) is authoritative.

Export and guides

  • Canvas chrome should expose export to OCIF, pretty JSON (same model), and SVG without burying them only in Save As.

  • Authoritative syntax / format guides for Plain encodings, CentrMark, and OCIF live in Dev-Centr docs (online). Apps may ship offline copies; online remains canonical for availability and updates.

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