Add infrastructure to build and publish as wasm32 (#3840)

Co-authored-by: Ingvar Stepanyan <me@rreverser.com>

Author: lovell

.github/workflows/ci.yml

@@ -161,6 +161,38 @@ jobs:
             npm install --ignore-scripts
             npx mocha --no-config --spec=test/unit/io.js --timeout=30000
             [[ -n $prebuild_upload ]] && cd src && ln -s ../package.json && npx prebuild || true
+  github-runner-emscripten:
+    permissions:
+      contents: write
+    name: wasm32 - prebuild
+    runs-on: ubuntu-22.04
+    container: "emscripten/emsdk:3.1.48"
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Dependencies
+        run: apt-get update && apt-get install -y pkg-config
+      - name: Dependencies (Node.js)
+        uses: actions/setup-node@v3
+        with:
+          node-version: "20"
+      - name: Install
+        run: emmake npm install --build-from-source
+      - name: Test
+        run: emmake npm test
+      - name: Test packaging
+        run: |
+          emmake npm run package-from-local-build
+          npm pkg set "optionalDependencies.@img/sharp-wasm32=file:./npm/wasm32"
+          npm run clean
+          npm install --cpu=wasm32
+          npm test
+      - name: Prebuild
+        if: startsWith(github.ref, 'refs/tags/')
+        env:
+          npm_config_nodedir: emscripten
+          prebuild_upload: ${{ secrets.GITHUB_TOKEN }}
+        run: cd src && ln -s ../package.json && emmake npx prebuild --platform=emscripten --arch=wasm32 --strip=0
   macstadium-runner:
     permissions:
       contents: write

docs/changelog.md

@@ -14,6 +14,9 @@ Requires libvips v8.15.0
 
 * Remove `sharp.vendor`.
 
+* Add experimental support for WebAssembly-based runtimes.
+  [@RReverser](https://github.com/RReverser)
+
 * Options for `trim` operation must be an Object, add new `lineArt` option.
   [#2363](https://github.com/lovell/sharp/issues/2363)
 

docs/humans.txt

@@ -278,3 +278,6 @@ GitHub: https://github.com/bianjunjie1981
 
 Name: Dennis Beatty
 GitHub: https://github.com/dnsbty
+
+Name: Ingvar Stepanyan
+GitHub: https://github.com/RReverser

docs/install.md

@@ -78,6 +78,15 @@ For cross-compiling, the `--platform`, `--arch` and `--libc` npm flags
 (or the `npm_config_platform`, `npm_config_arch` and `npm_config_libc` environment variables)
 can be used to configure the target environment.
 
+## WebAssembly
+
+Experimental support is provided for runtime environments that provide
+multi-threaded Wasm via Workers.
+
+```sh
+npm install --cpu=wasm32 sharp
+```
+
 ## FreeBSD
 
 The `vips` package must be installed before `npm install` is run.

docs/search-index.json

@@ -41,15 +41,23 @@ const runtimePlatformArch = () => `${process.platform}${runtimeLibc()}-${process
 
 /* istanbul ignore next */
 const buildPlatformArch = () => {
+  if (isEmscripten()) {
+    return 'wasm32';
+  }
   /* eslint camelcase: ["error", { allow: ["^npm_config_"] }] */
   const { npm_config_arch, npm_config_platform, npm_config_libc } = process.env;
-  return `${npm_config_platform || process.platform}${npm_config_libc || runtimeLibc()}-${npm_config_arch || process.arch}`;
+  const libc = typeof npm_config_libc === 'string' ? npm_config_libc : runtimeLibc();
+  return `${npm_config_platform || process.platform}${libc}-${npm_config_arch || process.arch}`;
 };
 
 const buildSharpLibvipsIncludeDir = () => {
   try {
-    return require('@img/sharp-libvips-dev/include');
-  } catch {}
+    return require(`@img/sharp-libvips-dev-${buildPlatformArch()}/include`);
+  } catch {
+    try {
+      return require('@img/sharp-libvips-dev/include');
+    } catch {}
+  }
   /* istanbul ignore next */
   return '';
 };
@@ -64,12 +72,22 @@ const buildSharpLibvipsCPlusPlusDir = () => {
 
 const buildSharpLibvipsLibDir = () => {
   try {
-    return require(`@img/sharp-libvips-${buildPlatformArch()}/lib`);
-  } catch {}
+    return require(`@img/sharp-libvips-dev-${buildPlatformArch()}/lib`);
+  } catch {
+    try {
+      return require(`@img/sharp-libvips-${buildPlatformArch()}/lib`);
+    } catch {}
+  }
   /* istanbul ignore next */
   return '';
 };
 
+/* istanbul ignore next */
+const isEmscripten = () => {
+  const { CC } = process.env;
+  return Boolean(CC && CC.endsWith('/emcc'));
+};
+
 const isRosetta = () => {
   /* istanbul ignore next */
   if (process.platform === 'darwin' && process.arch === 'x64') {
@@ -81,7 +99,7 @@ const isRosetta = () => {
 
 /* istanbul ignore next */
 const spawnRebuild = () =>
-  spawnSync('node-gyp rebuild --directory=src', {
+  spawnSync(`node-gyp rebuild --directory=src ${isEmscripten() ? '--nodedir=emscripten' : ''}`, {
     ...spawnSyncOptions,
     stdio: 'inherit'
   }).status;

lib/libvips.js

@@ -12,7 +12,9 @@ const runtimePlatform = runtimePlatformArch();
 
 const paths = [
   `../src/build/Release/sharp-${runtimePlatform}.node`,
-  `@img/sharp-${runtimePlatform}/sharp.node`
+  '../src/build/Release/sharp-wasm32.node',
+  `@img/sharp-${runtimePlatform}/sharp.node`,
+  '@img/sharp-wasm32/sharp.node'
 ];
 
 const errors = [];
@@ -47,6 +49,8 @@ if (!module.exports) {
     help.push(`    npm install --force @img/sharp-${runtimePlatform}`);
   } else {
     help.push(`- Manually install libvips >= ${minimumLibvipsVersion}`);
+    help.push('- Add experimental WebAssembly-based dependencies:');
+    help.push('    npm install --cpu=wasm32 sharp');
   }
   if (isLinux && /symbol not found/i.test(messages)) {
     try {

lib/sharp.js

@@ -59,11 +59,17 @@ let versions = {
 };
 /* istanbul ignore next */
 if (!libvipsVersion.isGlobal) {
-  try {
-    versions = require(`@img/sharp-${runtimePlatform}/versions`);
-  } catch (_) {
+  if (!libvipsVersion.isWasm) {
     try {
-      versions = require(`@img/sharp-libvips-${runtimePlatform}/versions`);
+      versions = require(`@img/sharp-${runtimePlatform}/versions`);
+    } catch (_) {
+      try {
+        versions = require(`@img/sharp-libvips-${runtimePlatform}/versions`);
+      } catch (_) {}
+    }
+  } else {
+    try {
+      versions = require('@img/sharp-wasm32/versions');
     } catch (_) {}
   }
 }

lib/utility.js

@@ -38,7 +38,8 @@ limitations under the License.
 `;
 
 workspaces.map(async platform => {
-  const url = `https://github.com/lovell/sharp/releases/download/v${version}/sharp-v${version}-napi-v9-${platform}.tar.gz`;
+  const prebuildPlatform = platform === 'wasm32' ? 'emscripten-wasm32' : platform;
+  const url = `https://github.com/lovell/sharp/releases/download/v${version}/sharp-v${version}-napi-v9-${prebuildPlatform}.tar.gz`;
   const dir = path.join(__dirname, platform);
   const response = await fetch(url);
   if (!response.ok) {
@@ -58,8 +59,8 @@ workspaces.map(async platform => {
   await writeFile(path.join(dir, 'README.md'), `# \`${name}\`\n\n${description}.\n${licensing}`);
   // Copy Apache-2.0 LICENSE
   await copyFile(path.join(__dirname, '..', 'LICENSE'), path.join(dir, 'LICENSE'));
-  // Copy Windows-specific files
-  if (platform.startsWith('win32-')) {
+  // Copy files for packages without an explicit sharp-libvips dependency (Windows, wasm)
+  if (platform.startsWith('win') || platform.startsWith('wasm')) {
     const sharpLibvipsDir = path.join(require(`@img/sharp-libvips-${platform}/lib`), '..');
     // Copy versions.json
     await copyFile(path.join(sharpLibvipsDir, 'versions.json'), path.join(dir, 'versions.json'));

npm/from-github-release.js

@@ -11,6 +11,7 @@
     "linux-x64",
     "linuxmusl-arm64",
     "linuxmusl-x64",
+    "wasm32",
     "win32-ia32",
     "win32-x64"
   ]