Export / Base Map
The codebase has no standalone
buildBaseMap()function. The current base_map export surface isexportApolloBin/exportApolloTextinsrc/io/mapIO.ts, which dispatches the heavy work intoapolloIO.worker.tsviaapolloIOBridge.
Exported symbols
// src/io/mapIO.ts
export function exportApolloBin(): Promise<void>;
export function exportApolloText(): Promise<void>;Source:
src/io/mapIO.ts:91-141.
The signatures are intentionally tiny — both functions read the current entity table and import/new-map context from stores; a new map opens the projection picker if no PROJ string exists yet:
function currentExportContext(): Promise<ExportContext | null>;If no import context exists and there are no exportable Apollo entities, the helper sets a human-readable error and returns without prompting for a save dialog.
Sequence
Filenames
suggestedFilename(originalName, ext) produces <base>-YYYYMMDDHHmmss.<ext>, keeping the original base name minus its .bin / .txt / .pb.txt extension. Round-tripping through edits never overwrites the source.
Progress
The bridge invokes onProgress as it streams entity chunks to the worker (default chunk = 2000 entities):
{
label: 'Exporting Apollo map',
detail: 'Sending entities 4,000 / 12,345',
progress: 0.05,
}useTaskProgressStore debounces visibility by 1 s so quick exports do not flash a transient spinner.
Errors
| Cause | Surface |
|---|---|
| No exportable Apollo entities | setError('Nothing to export - draw or import Apollo map elements first.') |
| Worker re-reconcile throws | Export failed: ${msg} + console.error |
| Imported-map cache is unavailable | Error: No imported Apollo map is cached in the IO worker |
Map.verify rejects entity shape | Forwarded as ERROR over apolloIOProtocol |
| Browser blocks anchor click | Rare; Chromium retries per its download policy |
Why no buildBaseMap()
The reconcile + projection + encode pipeline is heavy enough to lock the main thread on real Apollo maps, so the export logic intentionally stays inside the worker. A synchronous helper would only be useful in tests — and tests already import the worker code directly. Until that calculus changes, prefer the worker bridge.
Planned extensions
buildSimMap / buildRoutingMap do not yet exist. When they land, extend the worker with a runDerive branch and widen apolloIOProtocol.BEGIN_EXPORT.format to a tagged union. The mapIO helpers will then expose exportApolloSimMap / exportApolloRoutingMap without disturbing the base_map path.
See also
- Import / Parse Base Map — the inverse direction.
- io/apollo-io-bridge — promise gateway to the worker.
- io/apollo-io-protocol — message shapes that travel over the worker boundary.
Contributors
kent