pt/pf_app
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Write down what auto-pause actually does

Browse Source 
It reads like a paint optimisation and is not: pausing deletes the view, so
becoming visible again is a full rebuild. dataflow embeds the same viewer and
would hit the same stall, so it belongs in the shared reference next to the
other things that cost us a day to find.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
This commit is contained in:
Paul Trowbridge 2026-09-19 12:25:22 -04:00
parent d14036d1b5
commit 7217518cfd
1 changed files with 26 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
PERSPECTIVE.md
View File

@ -268,6 +268,32 @@ it would retire the `if(...)`-expression workaround. It costs the d3fc charts, t
column; both need validating, and the entry should be dropped rather than the layout.
Add this guard as part of adopting §3a, not after.
### Auto-pause deletes the view — turn it off for a static pivot
`<perspective-viewer>` auto-pauses by default: an `IntersectionObserver` on itself
(scrolled out of the viewport, `display: none`) combined with the document's
`visibilitychange` (backgrounded tab, minimized window). "Pause" is not a paint
optimisation — `session.set_pause(true)` runs `view_sub.take().delete()`, so the
**view object is destroyed**. Becoming visible again calls
`restore_and_render(…, ViewerConfigUpdate::default())`: a new view and a full
traversal, every time.
For a viewer streaming live updates nobody is watching, that is the right trade.
For a pivot over a large static table it is the wrong one — on pf_app's
`fc_osm_skinny_29` grain it is a multi-second stall on every tab switch, and it
silently discards per-node expand/collapse (§"Not fixed by any of this"), which
has no config representation and so cannot be restored.
```js
await viewer.load(table)
try { if (viewer.setAutoPause) await viewer.setAutoPause(false) } catch {}
```
Guard the call: it is a method on the custom element and absent on older builds.
Leave auto-pause **on** where the table is fed by a live stream the user does not
need to have kept up with while away. This is long-standing viewer behaviour, not
a 5.x regression — worth knowing before blaming a rebuild on your own code.
---
## 6. Build & deploy (target)