client-side pyramids/tiling documentation?

[sebastiangug]

I'm trying to use this library to generate some pyramids on the client side -- paired with an endpoint that returns S3-compatible signed urls.

I can't seem to find much documentation on tiling with either sharp or wasm-vips, I know by default vips will use the file system to save tiles on directories, so that's not an option in the browser, which will bring some limitations later on, that's fine for my use-case.

My hope is to load the image from an input field then generate each tile -> upload it -> move on.

I was hoping on finding some examples that go a bit more into depth around the methods and options available for tiling.

I'm happy to contribute some documentation after I figure it out.

[kleisauke]

wasm-vips doesn't currently support creating image pyramids with dzsave, as it's a bit tricky in Wasm since it requires more threads than the current threshold defined here:

wasm-vips/src/vips-library.js

Lines 15 to 16 in 31aeab4

	// Enforce a fixed thread pool by default on web
	ENV['VIPS_MAX_THREADS'] = {{{ PTHREAD_POOL_SIZE }}};

wasm-vips/src/CMakeLists.txt

Lines 176 to 179 in 31aeab4

	# libvips requires spawning at least VIPS_CONCURRENCY threads synchronously, with a minimum of 3 threads per
	# pipeline. This count includes the two write-behind background threads used by `vips_sink_disc`. To support up to
	# two concurrent pipelines, we need to double that number. Therefore, build with:
	# `-sPTHREAD_POOL_SIZE='Math.max(navigator.hardwareConcurrency, 6)'`.

Additionally, libarchive also needs to be compiled to make this work.

I can't seem to find much documentation on tiling with either sharp or wasm-vips

The libvips documentation has a chapter explaining how to make image pyramids.
https://www.libvips.org/API/current/Making-image-pyramids.html