A scan of 36 real files off the local disk took 8957ms — 249ms a frame — and
the page was idle for nearly all of it: a CPU profile over the walk is 61.5%
idle, so what the catalogue was doing was waiting, not working. Of that time the
bytes and the LibRaw preview are 2656ms and the tile 5761ms, while the EXIF read
is 14ms of the lot. One frame at a time spends the disk's latency and the
decoder's thread on nothing, and a JPEG was read whole — 8MB through a JS array
to find a date in its first kilobyte — then decoded at 24MP to be drawn at 512px.
The walk now runs four frames at a time. A frame that is new is read as a 256KB
header slice unless it is a RAW, which LibRaw has to have whole to seek to the
preview inside it; the shutter time comes off that slice. The tile is asked of
the decoder at 512 on the long edge, so a quarter of the pixels of a 24MP frame
are ever allocated, and the aspect comes from the frame's own SOF header for a
JPEG and from an eight-pixel decode for anything else; the canvas is left to
re-encode what comes back. The column still counts a frame the moment the scan
reaches it, so which frames are up is unchanged, and a frame that has not moved
is still dropped on its size and its time before a byte of it is read.
Measured on the same roll (24 JPEG 8.2MB + 12 RAW 22.6MB, two levels deep,
served over loopback with no added delay):
one frame at a time 8957ms 249ms/frame
four lanes 5474ms 152ms/frame
+ the header slice 4793ms 133ms/frame
Six lanes came out worse than four (5259ms) and is not what this does: past a
few the disk and the decoder are the limit.
Verified:
library-check.mjs — 35 steps, all passed. scan-nav-check.mjs and
roll-walk-check.mjs — all passed.
frontend tsc --noEmit clean. Live 8090 on index-CdakqRi8.js matching dist/:
/, /library and /app 200 with 0 console errors.
ponytail: the lanes run on the main thread, and a RAW still reads whole per file
— a few LibRaw opens at once now — so a 5000-frame folder is still lumpy; move
the walk into a worker and a RAW's preview onto a sync handle when that is real.
A frame smaller than 512 is now scaled up to it rather than drawn at its own
size, which is invisible at the 132–220px a tile is painted at; keep the old fit
if a print is ever taken off a tile.
Co-authored-by: PenguinHarness <noreply@penguin.local>
RecipesCam web — self-contained stack
A Docker-hosted web build of RecipesCam. Everything it needs is in this folder: move it to another machine, run two commands, and the app is up. It does not need the React Native project around it.
cp .env.example .env
docker compose up -d --build
# → http://localhost:8090
What runs where
| Service | Image | Role |
|---|---|---|
frontend |
nginx:1.27-alpine (built by frontend/Dockerfile) |
Static SPA + /api/ reverse proxy |
api |
node:22-slim (built by backend/Dockerfile) |
Accounts + saved recipes, SQLite on ./data |
frontend resolves api through Docker's embedded DNS and proxies /api/* to
it — that is why the API container is named api and why it is not published on
the host. Only ${WEB_PORT:-8090} is exposed.
Photos never leave the browser. The CanvasKit render pipeline (grade, frame, watermarks, JPEG encode) runs in the visitor's tab; the API only stores recipes as JSON.
Layout
docker-compose.yml the stack
.env.example WEB_PORT
data/ SQLite (created on first run, gitignored)
backend/ Fastify + better-sqlite3 API, own Dockerfile
frontend/ Vite + React + CanvasKit SPA, own Dockerfile + nginx.conf
shared/ vendored copies of the app's types + utils (see below)
src/engine/ skiaShim.ts (CanvasKit) + exportEngine.ts (render pipeline)
+ session.ts (localStorage/IndexedDB studio persistence)
Vendored files
frontend/shared/{types/index.ts,utils/*.ts} are byte-identical copies of
src/types/index.ts and ten src/utils/*.ts files from the React Native
project (@shopify/react-native-skia is aliased to src/engine/skiaShim.ts in
vite.config.ts + tsconfig.json, so those files compile unchanged):
cinemaShader colorUtils defaultRecipes exifWrite frameUtils jpegDpi
paramDefs recipeShare skiaImage toneShader.
The landing page needs no CDN: frontend/public/assets/fonts/*.woff2 are the
seven self-hosted faces behind the three font groups the Themes menu offers
(Plus Jakarta Sans / Inter / JetBrains Mono, Fraunces / Be Vietnam Pro /
Courier Prime, Be Vietnam Pro / Space Mono — all SIL OFL, pulled from Google
Fonts, vietnamese + latin + latin-ext subsets), and
frontend/public/assets/samples/s*.jpg are the six placeholder negatives the
film strip, preset tester and QR card show (swap them for real graded stills
whenever we have them). Its one foreign request is the QR image from
api.qrserver.com, which degrades to an empty slot offline.
When the app changes one of them, copy it back in — the renderer is only "parity" for as long as these stay in sync:
cd <repo>/docker/frontend/shared/utils
cp <repo>/src/utils/<name>.ts .
Operations
docker compose logs -f api # API log
docker compose restart api # after backend/src changes (rebuild: --build)
docker compose down # stop; ./data survives
Backup is the ./data folder — that is the whole database.
Checks
curl -s http://localhost:8090/api/health # {"ok":true}
curl -sI http://localhost:8090/ # 200, index.html
Then open the UI, drop a photo in, and confirm the preview shows the picture and
EXPORT downloads a JPEG that opens. The preview going solid black while the
export still reports a plausible size is the one failure mode worth knowing: it
means the CanvasKit GPU surfaces lost their shared GrDirectContext (see
frontend/src/engine/skiaShim.ts), and with no GPU the raster fallback renders
the same pipeline correctly, just slower.