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@ue-too/board / CameraUpdatePublisher

Class: CameraUpdatePublisher ​

Defined in: packages/board/src/camera/update-publisher.ts:212

Event publisher for camera state changes using the Observable pattern. Manages subscriptions and notifications for pan, zoom, and rotate events.

Remarks ​

This class is used internally by DefaultBoardCamera to implement the event system. You typically don't instantiate this directly unless building custom camera implementations.

Each specific event (pan, zoom, rotate) also triggers the 'all' event, allowing listeners to subscribe to any camera change with a single handler.

Example ​

typescript
const publisher = new CameraUpdatePublisher();

// Subscribe to pan events
publisher.on('pan', (event, state) => {
  console.log('Camera panned:', event.diff);
});

// Notify subscribers of a pan event
publisher.notifyPan(
  { diff: { x: 10, y: 20 } },
  { position: { x: 100, y: 200 }, zoomLevel: 1, rotation: 0 }
);

See ​

DefaultBoardCamera for the primary consumer of this class

Constructors ​

Constructor ​

new CameraUpdatePublisher(): CameraUpdatePublisher

Defined in: packages/board/src/camera/update-publisher.ts:221

Creates a new camera event publisher with async observables for each event type.

Returns ​

CameraUpdatePublisher

Methods ​

notifyPan() ​

notifyPan(event, cameraState): void

Defined in: packages/board/src/camera/update-publisher.ts:235

Notifies all pan event subscribers. Also triggers the 'all' event with type discrimination.

Parameters ​

event ​

CameraPanEventPayload

Pan event payload containing position delta

cameraState ​

CameraState

Current camera state snapshot

Returns ​

void

notifyRotate() ​

notifyRotate(event, cameraState): void

Defined in: packages/board/src/camera/update-publisher.ts:262

Notifies all rotation event subscribers. Also triggers the 'all' event with type discrimination.

Parameters ​

event ​

CameraRotateEventPayload

Rotation event payload containing rotation delta

cameraState ​

CameraState

Current camera state snapshot

Returns ​

void

notifyZoom() ​

notifyZoom(event, cameraState): void

Defined in: packages/board/src/camera/update-publisher.ts:247

Notifies all zoom event subscribers. Also triggers the 'all' event with type discrimination.

Parameters ​

event ​

CameraZoomEventPayload

Zoom event payload containing zoom delta

cameraState ​

CameraState

Current camera state snapshot

Returns ​

void

on() ​

on<K>(eventName, callback, options?): UnSubscribe

Defined in: packages/board/src/camera/update-publisher.ts:321

Subscribes to camera events with type-safe callbacks and optional AbortController support.

Type Parameters ​

K ​

K extends keyof CameraEventMap

The event type key from CameraEventMap

Parameters ​

eventName ​

K

Event type to subscribe to ('pan', 'zoom', 'rotate', or 'all')

callback ​

(event, cameraState) => void

Function called when the event occurs

options? ​

SubscriptionOptions

Optional subscription options including AbortController signal

Returns ​

UnSubscribe

Function that unsubscribes this callback when called

Throws ​

Error if an invalid event name is provided

Remarks ​

Use the AbortController pattern for managing multiple subscriptions:

Example ​

typescript
// Basic subscription
const unsubscribe = publisher.on('pan', (event, state) => {
  console.log(`Panned by (${event.diff.x}, ${event.diff.y})`);
});

// Later: unsubscribe
unsubscribe();

// Using AbortController for batch management
const controller = new AbortController();
publisher.on('pan', handlePan, { signal: controller.signal });
publisher.on('zoom', handleZoom, { signal: controller.signal });

// Unsubscribe all at once
controller.abort();

// Subscribe to all events with type discrimination
publisher.on('all', (event, state) => {
  switch (event.type) {
    case 'pan':
      console.log('Pan:', event.diff);
      break;
    case 'zoom':
      console.log('Zoom:', event.deltaZoomAmount);
      break;
    case 'rotate':
      console.log('Rotate:', event.deltaRotation);
      break;
  }
});