Track view-scoped overlay placements and retain portalled editors

src/lib/canvas-bindings/index.ts

@@ -19,3 +19,5 @@ export {createPaintIndex} from './paint-index.ts';
 export type {PaintRegion} from './paint-index.ts';
 export {projectedPaintOverflow,createProjectedPaintIndex} from './projected-paint.ts';
 export {projectedConnectionPaintOverflow} from './connection-paint.ts';
+export {createOverlayIndex} from './overlays.ts';
+export type {OverlayEntry,OverlayIndex} from './overlays.ts';

src/lib/canvas-bindings/overlays.ts

@@ -0,0 +1,17 @@
+import type {Target} from '../canvas-core/types.ts';
+import type {Rect} from '../canvas-core/geometry.ts';
+import {createPaintIndex} from './paint-index.ts';
+import {fault} from '../canvas-core/values.ts';
+export type OverlayEntry={readonly id:string;readonly viewId:string;readonly placement:string;readonly target:Target;readonly bounds:Rect;readonly focused:boolean;readonly composing:boolean};
+/** Ephemeral screen-space placements. A lease prevents late cleanup from removing a replacement. */
+export function createOverlayIndex(viewId:string){
+ if(typeof viewId!=='string'||!viewId)throw fault('view_session_required');let serial=0,snapshot:readonly OverlayEntry[]=Object.freeze([]);const entries=new Map<string,{token:number;entry:OverlayEntry}>(),listeners=new Set<()=>void>(),index=createPaintIndex();
+ function publish(){snapshot=Object.freeze([...entries.values()].map(row=>row.entry));index.sync(snapshot.map(entry=>({id:entry.id,bounds:entry.bounds})));for(const listener of [...listeners])listener();}
+ function capture(id:string,value:Omit<OverlayEntry,'id'|'viewId'>):OverlayEntry{if(typeof id!=='string'||!id||typeof value.placement!=='string'||!value.placement||typeof value.target.id!=='string'||!value.target.id||!Number.isSafeInteger(value.target.incarnation)||value.target.incarnation<1)throw fault('invalid_overlay');const entry=Object.freeze({...value,id,viewId,target:Object.freeze({...value.target}),bounds:Object.freeze({...value.bounds})});const check=createPaintIndex();check.sync([{id,bounds:entry.bounds}]);return entry;}
+ return Object.freeze({viewId,getSnapshot:()=>snapshot,subscribe(listener:()=>void){listeners.add(listener);return()=>{listeners.delete(listener);};},
+  register(id:string,value:Omit<OverlayEntry,'id'|'viewId'>){const token=++serial,entry=capture(id,value);entries.set(id,{token,entry});publish();return Object.freeze({update(value:Omit<OverlayEntry,'id'|'viewId'>){if(entries.get(id)?.token!==token)return;const entry=capture(id,value),old=entries.get(id)!.entry;if(JSON.stringify(old)===JSON.stringify(entry))return;entries.set(id,{token,entry});publish();},release(){if(entries.get(id)?.token!==token)return;entries.delete(id);publish();}});},
+  visible(bounds:Rect,current:(target:Target)=>boolean){const ids=index.query(bounds);return snapshot.filter(entry=>current(entry.target)&&(entry.focused||entry.composing||ids.has(entry.id)));},
+  clear(){entries.clear();publish();},
+ });
+}
+export type OverlayIndex=ReturnType<typeof createOverlayIndex>;