FX had two tools that change the photo where it is — HEAL repairs a speck, MOSAIC hides a patch — and every knob that graded the frame graded all of it. The scratchpad's gradient_mask.md asks for the two local adjustments the phone's own editor has and Lightroom made familiar: a linear gradient and a radial one. This is that spec, written for the renderer this app actually has. A mask is a SHAPE rather than a value, so it is dragged rather than turned: the LINEAR chip arms a ramp and the next drag on the photo is its two ends — zero at the press, one at the release, the spec's own convention, which is what makes the same gesture a wide fade or a hard edge — and RADIAL arms an ellipse whose centre is the press, whose semi-axes are the drag's own distance and whose axis lies along the direction the hand went, so the circle a drag describes is the circle the mask starts life as. Both shapes keep a pin (the whole shape travels by it) and, while chosen, the handles that move the ends or the axes and the one that turns the ellipse; what is drawn is the shape the render will read, so the ramp and the rim are visible before a knob is moved. Inside the shape, three knobs grade in the spec's own order and its own maths: exposure as `pow(2.0, e)` in stops (its -5..+5), contrast about the middle, saturation as a mix away from the pixel's own REC-709 luma — the mixer's -10..+10 read as the spec's -1..+1 — and a radial mask adds the feather it fades over, which is the fraction of its own axis the alpha holds full before it dies at the rim. Several masks run in the order they were drawn, each reading what the one before it left, which is what a stack of local adjustments is. The maths is GLSL in the md and the renderer is Skia (canvaskit-wasm, SkSL runtime effects), so it is ported stage for stage: one pass, after the frame-wide grade and the vignette and before HEAL, because a local adjustment is part of the look and not a repair — the pixels a repair borrows are then meant to carry the mask's light already. Preview and export both come through renderPhoto, so the file carries the masks the stage is showing by construction, and the shape and the knobs ride in the recipe's own JSON, which is what makes them survive a save. The chips sit with HEAL and MOSAIC because all four take the pointer on the photo, and they are exclusive with every other armed tool, the eyedropper included — while a mask tool is armed the layer takes the photo, so a drag means "draw the next shape" and a press on a pin means "take hold of this one", which is why the shapes already laid are answered through their pin and handles alone. A knob drag on a mask is one undo step, a shape drag is one more, a press that only chose a mask records nothing at all, and RESET is the way back with the whole frame as it was imported. ponytail: the spec's own "Gợi ý nâng cấp" rung — Highlights and Shadows isolated with pow(luma, 3) and pow(1-luma, 3) weight masks — is not here, and neither is Lightroom's per-mask invert and colour/tone range. The three knobs are what "gradient mask" means until a photo shows a sky that has to be rescued apart from the grass under it; the md itself calls it an upgrade, not the feature. Verified: tsc clean; mask-probe 35/0 on the dev server and again on 8090 (the two chips, both shapes drawn and moved and turned, the ramp read off the pixels — 61 -> 244 at the release and 61 at the press — the feather read off the rings, DELETE/UNDO/REDO/CLEAR, and one gesture one undo step); brush-edit 33/0, heal-idle 23/0, heal-zoom-drag 28/0, landing/pro-gate/award-column/otp-code/ tone-curve all ALL PASS, backend 180/0.
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.