Measure angles in images and video frames, entirely in the browser. Load a photo or video, place three points to form an angle, read off the value, and save the annotated image.
All processing happens client side. The app is a static WASM bundle that runs in any browser with WebAssembly support, and no media ever leaves it.
- Load any number of images plus one video, in any format the browser can decode. Each image and each captured video frame becomes a frame of its own in the thumbnail strip, and frames can be deleted individually.
- For videos: scrub to any position, step by single frames or seconds, and capture as many frames as needed.
- Drag three points (two ends and a vertex) on the selected frame. The angle between the two lines is displayed live in degrees from 0 to 180, with a magnifier loupe for precise placement.
- Zoom the frame with the mouse wheel, a two-finger pinch or the zoom buttons, and pan it by dragging the frame with the mouse or one finger.
- Keyboard access: focus a handle with Tab and nudge it with the arrow keys (hold Shift for larger steps).
- Save the frame with the angle overlay baked in as a PNG. The export always uses the full resolution of the source image, whatever the current zoom is.
The only prerequisite is Nix with flakes enabled. The dev shell provides the whole toolchain: Rust with the wasm target and the Dioxus tooling for the app itself, plus the Python linters and Playwright with a Chromium build for the checks and the end-to-end tests.
Enter the shell with nix develop, or run direnv allow once to have it loaded automatically by the checked-in .envrc. Inside the shell:
dx serve # development server with hot reload (under /angulito/)
make build # release bundle in target/dx/angulito/release/web/public
make check # version pins, formatting, clippy, ruff, ty
make test # unit tests + end-to-end tests
make all # check + test
make format # apply formatting and lint fixes
make screenshot # regenerate docs/screenshot.jpg
make clean # remove build output and tool cachesSingle commands can be run without entering the shell, which is how the checks on every pull request invoke them (.github/workflows/verify.yml):
nix develop -c make allThe bundle produced by make build can be served by any static file server.
The flake provides a shell on Linux and macOS, but only x86_64-linux is covered by CI. The end-to-end tests have only been run on Linux.
Dependency updates are opened daily by Renovate and auto-merged once the checks pass (.github/renovate.json5). One thing is outside that and is bumped by hand: the dioxus and wasm-bindgen versions in Cargo.toml. They are exact pins that must match the CLI versions shipped by nixpkgs, so they move together with flake.lock. A lock file refresh that outgrows the pins fails on make check, which compares the pins against the CLIs and names the crate that drifted.
Auto-merge relies on two branch protection settings on main that cannot be configured from the repository files: the test job has to be a required status check, and "Require branches to be up to date before merging" has to be enabled. Renovate rebases a pull request that fell behind main once it is otherwise ready to merge, so the up-to-date rule does not leave it stuck.
Every push to main runs the checks and tests and then deploys to GitHub Pages (.github/workflows/deploy.yml), publishing the same bundle the end-to-end tests ran against.
The deployment relies on one setting that cannot be configured from the repository files: the Pages source has to be set to GitHub Actions in the repository settings, or the deploy job fails.
The app is served under https://treiher.github.io/angulito/, which is why base_path is set to angulito in Dioxus.toml, and why dx serve also serves under /angulito/ locally.
Copyright (C) 2026 Tobias Reiher
Angulito is licensed under the GNU Affero General Public License v3.0.
The demo image shown in the screenshot above was AI-generated and does not depict a real person.
