Enhancement — more modular loading

[alexandergunnarson]

First off, let me say how impressed I am with wasm-vips — amazing job 🤩👏🥳 Can't tell you how great your lib "just works" in comparison to about 8 other browser-based image manipulation libs I've tried, despite its supposed alpha quality. (If this is alpha quality, all the other libs are laughably early pre-alphas!)

The suggestion here is around more modular loading. The dynamicLibraries option is super helpful and shaves off quite a few unnecessary MB. However, I was wondering whether we could extend the concept to some of the more "core" Vips functionality. For instance, I only need webp resizing and encoding. I realize tree-shaking WASM is not yet a thing and may never be, but perhaps it's possible to further granulate wasm-vips analogously to dynamicLibraries. For instance I can imagine passing only features: ["resize", "web-encode"] or however the API might look.

Probably a big ask because ostensibly libvips itself isn't modular in the way I'm describing, but worth a discussion, I think.

Thanks again!

[alexandergunnarson]

In practice, WASM streaming mitigates this, but I can imagine situations where it won't be the definitive band-aid.

[kleisauke]

Hi @alexandergunnarson,

Sorry for the delay. A significant portion of the vips.wasm file size comes from the foreign loaders and savers. A minimal libvips (i.e. with only core functionality) can be configured using this patch:

--- a/build.sh
+++ b/build.sh
@@ -488,11 +488,7 @@ node --version
   sed -i "/subdir('man')/{N;N;N;N;d;}" meson.build
   meson setup _build --prefix=$TARGET --cross-file=$MESON_CROSS --default-library=static --buildtype=release \
     -Ddeprecated=false -Dexamples=false -Dcplusplus=$LIBVIPS_CPP -Dauto_features=disabled \
-    ${ENABLE_MODULES:+-Dmodules=enabled} -Dcgif=enabled -Dexif=enabled ${ENABLE_AVIF:+-Dheif=enabled} \
-    -Dheif-module=enabled -Dimagequant=enabled -Djpeg=enabled ${ENABLE_JXL:+-Djpeg-xl=enabled} \
-    -Djpeg-xl-module=enabled -Dlcms=enabled ${ENABLE_SIMD:+-Dhighway=enabled} ${ENABLE_SVG:+-Dresvg=enabled} \
-    -Dresvg-module=enabled -Dspng=enabled -Dtiff=enabled -Dwebp=enabled -Dnsgif=true -Dppm=true -Danalyze=true \
-    -Dradiance=true -Dzlib=enabled
+    -Dnsgif=false -Dppm=false -Danalyze=false -Dradiance=false
   meson install -C _build --tag runtime,devel
   # Emscripten requires linking to side modules to find the necessary symbols to export
   module_dir=$(printf '%s\n' $TARGET/lib/vips-modules-* | sort -n | tail -1)

And by compiling with -Oz instead of -O3, using:

--- a/build.sh
+++ b/build.sh
@@ -111,7 +111,7 @@ done
 export RUSTFLAGS="-Ctarget-feature=+atomics,+bulk-memory,+nontrapping-fptoint"
 
 # Common compiler flags
-COMMON_FLAGS="-O3 -pthread"
+COMMON_FLAGS="-Oz -pthread"
 if [ "$LTO" = "true" ]; then
   COMMON_FLAGS+=" -flto"
   export RUSTFLAGS+=" -Clto -Cembed-bitcode=yes"

With that, I see:

$ ls -lh lib/*.wasm | awk '{print $5,$9}'
2.9M lib/vips-O3.wasm
2.2M lib/vips-Oz.wasm

However, most WebAssembly files are served Brotli-compressed nowadays. In the ideal case, with v0.0.8, this would mean that ~1.5MiB is transferred over the network.

$ brotli node_modules/wasm-vips/lib/vips.wasm --best -v
Compressed [node_modules/wasm-vips/lib/vips.wasm]: 5.388 MiB -> 1.509 MiB in 8.49 sec

(usually the size is ~1.8MiB due to the use of compression level 4, as shown in your screenshot)

Running the same command over the produced WebAssembly binaries above, I see:

$ brotli lib/vips-O{3,z}.wasm --best -v
Compressed [lib/vips-O3.wasm]: 2.872 MiB -> 968.115 KiB in 4.98 sec
Compressed [lib/vips-Oz.wasm]: 2.144 MiB -> 896.830 KiB in 4.26 sec

I think that modularizing every operation within wasm-vips adds unnecessary complexity to the build logic without yielding any significant benefits. We could, however, experiment with making more foreign loaders/savers as dynamic module.

Let's tag this as an enhancement.

[alexandergunnarson]

Sorry for my own delay. Thanks for your thorough response — some great ideas here!