calternal_collab::canvas

Whole-element Canvas events for the server’s Yrs document (DESIGN §60, #976).

Clients submit elements, not Yrs structs. Only the authenticated server transaction writes the map, so client IDs cannot override the Excalidraw version/nonce rule or spoof the author. Image bytes stay in Home files or unchanged legacy source, outside this map and the later update log (#989).

Source: crates/calternal-collab/src/canvas.rs

Functions

apply_elements

pub fn apply_elements(doc: &Doc, base: &Value, updates: &[Value], author: &str) -> Result<bool>

Validate an entire event before one author-bound transaction changes the map. A stale update is a no-op. Deletion uses a tombstone, never map removal.

Source: crates/calternal-collab/src/canvas.rs:144

elements

pub fn elements(doc: &Doc) -> Result<Vec<Value>>

Read whole values in fractional index order with ID as a deterministic tie.

Source: crates/calternal-collab/src/canvas.rs:94

from_scene

pub fn from_scene(scene: &Value) -> Result<Doc>

Build the rebuildable room state. Unknown scene and image fields stay on disk.

Source: crates/calternal-collab/src/canvas.rs:22

Constants

ELEMENTS

pub const ELEMENTS: &str

Stable map name used by every Canvas client.

Source: crates/calternal-collab/src/canvas.rs:14

MAX_EVENT_BYTES

pub const MAX_EVENT_BYTES: usize

Smaller than Notes frames because Canvas updates never carry image bytes.

Source: crates/calternal-collab/src/canvas.rs:18

MESSAGE_CANVAS_ELEMENTS

pub const MESSAGE_CANVAS_ELEMENTS: u8

The one accepted Canvas event kind. Its author is supplied by the connection.

Source: crates/calternal-collab/src/canvas.rs:454