269aa36f82
* ✨ Export solid inner and outer strokes to WASM SVG SkSVGDevice drops save_layer+Clear used for path Outer strokes, so solid Inner/Outer strokes on closed shapes are expanded to filled outlines via stroke_to_path. Center and open paths stay on the shared stroke path. Closes #11381 * ✨ Export dotted, dashed, and mixed strokes to WASM SVG PathEffects do not survive SkSVGDevice, so dotted/dashed/mixed strokes expand via stroke_to_path with the effect kept, producing filled outline geometry for all alignments including Center. Closes #11382 * 🐛 Fix WASM SVG stroke export edge cases Keep expanded stroke outlines in local space under the leaf CTM so rotated rects/paths are not double-transformed; overlay open-path caps after dotted expansion; draw frame strokes outside the content clip; and route per-side rect/frame strokes through the evenodd band path.
Penpot WASM render
This is the canvas-based WebAssembly render engine for Penpot.
Rust & Emscripten
This project is a Rust crate that targets Emscripten (wasm32-unknown-emscripten).
We use wasm32-unknown-emscripten compilation target:
- It compiles Rust code into WASM
- It generates the JavaScript code (“glue”) to load and run the WASM code
Skia
We use Skia, an Open Source 2D graphics library. In particular, the render engine uses Skia via custom binaries of the rust-skia crate.
How to build
With the Penpot Development Environment running, create a new tab in the tmux.
cd penpot/render-wasm
./build
You can also use ./watch to run the build on every change.
The build script will compile the project and copy the .js and .wasm files to their correct location within the frontend app.
Render targets
The same Rust source produces two artifacts, which differ only in compiler options:
| Target | Tuned for | Cargo profile | Consumed by |
|---|---|---|---|
frontend |
speed | release (-O3) |
frontend/resources/public/js |
export |
size | size (-Oz) |
exporter/resources/wasm |
./build # both targets, frontend first
./build frontend # workspace / viewer renderer
./build export # headless exporter renderer
./watch still follows a single target (frontend unless you pass one),
since watching both would rebuild twice on every keystroke.
Each target keeps its own CARGO_TARGET_DIR (target/<target>), so switching
between them does not invalidate the other's cache. Set BUILD_MODE=release
(or NODE_ENV=production) for an optimized build; the default is debug.
Each target writes its own generated shared.js (the enum discriminants the
CLJS side compiles against) next to the code that imports it — respectively
frontend/src/app/render_wasm/api/shared.js and
exporter/src/app/wasm/shared.js. Neither build writes to the other's paths.
Edit your local frontend/resources/public/js/config.js to add the following flags:
enable-feature-render-wasmto enable this render engine.enable-render-wasm-dpr(optional), to enable using the device pixel ratio.
How to test
We currently have two types of tests:
- Unit tests
cd penpot/render-wasm
./test