90 lines
4.2 KiB
Markdown
90 lines
4.2 KiB
Markdown
# Hosting LightCraft for the web
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`lightcraft-web-<version>.zip` (from the GitHub release, or `packaging/web/package.sh`) holds a
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static site in `lightcraft-web-<version>/`:
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| File | What it is |
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|---|---|
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| `index.html` | The page. It loads everything through relative URLs. |
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| `lightcraft-web-<hash>.js` | wasm-bindgen glue (generated, ES module) |
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| `lightcraft-web-<hash>_bg.wasm` | The app, about 13 MB, or 5 MB with compression |
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| `_headers`, `.htaccess` | Sample header rules for Netlify/Cloudflare Pages and Apache |
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There is no server-side code. Upload the folder's contents anywhere that serves static files.
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## Any path works
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All URLs in `index.html` are relative (`public_url = "./"` in `apps/lightcraft-web/Trunk.toml`),
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so the site works at a domain root (`https://example.com/`), under a prefix
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(`https://example.com/tools/lightcraft/`) and from a CDN bucket. The asset names carry a content
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hash, so they can be cached forever. Only `index.html` needs revalidation.
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## Required server settings
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- **MIME type:** serve `.wasm` as `application/wasm`. Browsers refuse to stream-compile it under
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any other type, and the app then loads slowly or not at all. Serve `.js` as `text/javascript`.
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Most hosts already do both. For nginx, check that `mime.types` has `application/wasm wasm;`.
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- **Compression:** turn on gzip or Brotli for `.wasm`, `.js` and `.html`. That takes the
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download from about 13 MB to about 5 MB. You can also precompress (`brotli -k *.wasm`) and let
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the server send `Content-Encoding: br`.
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- **Caching:** `Cache-Control: public, max-age=31536000, immutable` on the hashed `.wasm` and
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`.js` files, and `no-cache` on `index.html`.
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- **HTTPS:** WebGPU (and the clipboard) only work in a secure context, which means `https://`
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or `http://localhost`. Over plain HTTP elsewhere, the app falls back to WebGL2.
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- **No special isolation headers:** LightCraft doesn't use `SharedArrayBuffer`, so it doesn't
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need `Cross-Origin-Opener-Policy` or `Cross-Origin-Embedder-Policy`. If your site already sends
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COEP `require-corp`, also send `Cross-Origin-Resource-Policy: same-origin` (or `cross-origin`
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when the files live on a CDN) on the app's files.
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nginx example:
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```nginx
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location /lightcraft/ {
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types { application/wasm wasm; text/javascript js; text/html html; }
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gzip on;
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gzip_types application/wasm text/javascript text/html;
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location ~* \.(wasm|js)$ { add_header Cache-Control "public, max-age=31536000, immutable"; }
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location ~* index\.html$ { add_header Cache-Control "no-cache"; }
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}
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```
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Local test: `python3 -m http.server 8765` inside the folder, then open http://localhost:8765/.
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## Embedding in a page (iframe)
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```html
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<iframe
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src="https://example.com/lightcraft/"
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title="LightCraft image editor"
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style="width: 100%; height: 720px; border: 0;"
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allow="fullscreen; clipboard-read; clipboard-write"
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allowfullscreen>
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</iframe>
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```
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- The app fills the iframe and follows its size, so size the iframe and not the app.
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- Keyboard shortcuts go to the iframe after the user clicks into it, as with any embedded app.
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- **Cross-origin embeds** work. Preferences are kept in the iframe's `localStorage`. Browsers
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that partition or block third-party storage may forget them between visits, and the app
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then starts with defaults.
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- **Sandboxed iframes** need at least
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`sandbox="allow-scripts allow-same-origin allow-downloads allow-popups"`. Without
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`allow-same-origin` there's no storage. Without `allow-downloads`, Save and Export (browser
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downloads) are blocked.
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- Don't send `X-Frame-Options: DENY` or a `frame-ancestors` CSP that excludes the embedding page.
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## Renderer selection and fallback flags
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LightCraft renders with wgpu. It uses **WebGPU** when the browser has it and falls back to
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**WebGL2** on its own. URL query flags override this, and they work on the iframe `src` too:
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| Flag | Effect |
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| *(none)* | WebGPU if available, otherwise WebGL2 |
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| `?webgl` | Force the WebGL2 backend (useful when a WebGPU driver misbehaves) |
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| `?cpu` | Force the CPU canvas path (slowest, most compatible) |
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For example: `<iframe src="https://example.com/lightcraft/?webgl" ...>`.
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A browser with neither WebGPU nor WebGL2 gets a message in place of the app.
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