WebAssembly build

.gitattributes

@@ -1 +1,2 @@
 src/libvips/* linguist-vendored
+build/Release/sharp-emscripten-wasm32.node.* linguist-generated

.github/workflows/ci.yml

@@ -7,7 +7,7 @@ jobs:
   CI:
     permissions:
       contents: write # for npx prebuild to make release
-    name: ${{ matrix.container || matrix.os }} - Node.js ${{ matrix.nodejs_version }} ${{ matrix.nodejs_arch }} ${{ matrix.prebuild && '- prebuild' }}
+    name: ${{ matrix.container || matrix.os }} - Node.js ${{ matrix.nodejs_version }} ${{ matrix.addon_arch || matrix.nodejs_arch }} ${{ matrix.prebuild && '- prebuild' }}
     runs-on: ${{ matrix.os }}
     container: ${{ matrix.container }}
     strategy:
@@ -31,6 +31,9 @@ jobs:
             container: node:16-alpine3.12
           - os: ubuntu-22.04
             container: node:18-alpine3.14
+          - os: ubuntu-22.04
+            container: node:18-alpine3.14
+            addon_arch: wasm32
           - os: macos-11
             nodejs_version: 14
             prebuild: true
@@ -95,9 +98,17 @@ jobs:
         if: matrix.container
         run: chown root.root .
       - name: Install
+        if: matrix.addon_arch != 'wasm32'
         run: npm install --build-from-source --unsafe-perm
+      - name: Install (WebAssembly)
+        if: matrix.addon_arch == 'wasm32'
+        run: npm install --ignore-scripts
       - name: Test
+        if: matrix.addon_arch != 'wasm32'
         run: npm test
+      - name: Test (WebAssembly)
+        if: matrix.addon_arch == 'wasm32'
+        run: npx --arch=wasm32 mocha
       - name: Prebuild
         if: matrix.prebuild && startsWith(github.ref, 'refs/tags/')
         env:

.gitignore

@@ -1,4 +1,7 @@
-build
+build/*
+!build/Release
+build/Release/*
+!build/Release/sharp-emscripten-wasm32.node.*
 node_modules
 /coverage
 test/bench/node_modules
@@ -16,3 +19,4 @@ vendor
 package-lock.json
 .idea
 .firebase
+/wasm-scripts/wasm-vips

binding.gyp

@@ -77,8 +77,12 @@
       'libvips-cpp'
     ],
     'variables': {
-      'runtime_link%': 'shared',
       'conditions': [
+        ['OS != "emscripten"', {
+          'runtime_link%': 'shared',
+        }, {
+          'runtime_link%': 'static',
+        }],
         ['OS != "win"', {
           'pkg_config_path': '<!(node -p "require(\'./lib/libvips\').pkgConfigPath()")',
           'use_global_libvips': '<!(node -p "Boolean(require(\'./lib/libvips\').useGlobalLibvips()).toString()")'
@@ -101,6 +105,39 @@
       '<!(node -p "require(\'node-addon-api\').include_dir")',
     ],
     'conditions': [
+      ['OS == "emscripten"', {
+        # .js because that's how Emscripten knows what to build, and .node
+        # in front so that `require('[...].node')` would just work.
+        'product_extension': 'node.js',
+        'defines': [
+          # Limit to 1 async task to avoid stealing threads from the pool
+          # that are intended for libvips.
+          'EMNAPI_WORKER_POOL_SIZE=1',
+        ],
+        'cflags': ['-g2'],
+        'ldflags': [
+          '-g2',
+          '-fexceptions',
+          # We don't know in advance how large images will be, best to allow growth
+          # rather than overallocate in resource-constrained environments.
+          '-sALLOW_MEMORY_GROWTH',
+          # Building for Node.js, we want sync instantiation for compat with native
+          '-sWASM_ASYNC_COMPILATION=0',
+          # Re-export emnapi bindings as the main exports
+          '--pre-js=<!(node -p "require.resolve(\'./wasm-scripts/pre.js\')")',
+          # Using JS implementation of text decoder is actually faster when using pthreads.
+          '-sTEXTDECODER=0',
+          # Support 64-bit integers.
+          '-sWASM_BIGINT',
+
+          # We're building only for Node.js for now
+          '-sENVIRONMENT=node',
+          # Propagate filesystem to Node.js.
+          '-sNODERAWFS',
+          # Exit helpers
+          '-sEXPORTED_FUNCTIONS=["_vips_shutdown", "_uv_library_shutdown"]',
+        ],
+      }],
       ['use_global_libvips == "true"', {
         # Use pkg-config for include and lib
         'include_dirs': ['<!@(PKG_CONFIG_PATH="<(pkg_config_path)" pkg-config --cflags-only-I vips-cpp vips glib-2.0 | sed s\/-I//g)'],