`canvas` should not be a dependency if possible

[tamuratak]

canvas has been added to the dependency, not devDependency, since v3.0.279. I don't think it is a good idea. Because node-canvas prebuilds aren't available for ARM, users with macOS on ARM will request helps from you, which would increase the maintenance burden. We can say the same thing for users with old Linux for which node-canvas prebuilds aren't available.

When GitHub actions supports macOS on ARM, the situation would change.

• https://github.com/Automattic/node-canvas/issues/1511

• https://github.com/mozilla/pdfjs-dist/blob/f6eefc659269fe422cc350fe2eef769251eec33d/package.json#L15-L18

  "dependencies": {
  "canvas": "^2.10.1",
  "web-streams-polyfill": "^3.2.1"
  },

Configuration:

• PDF.js version: 3.0.279

[Snuffleupagus]

What do you actually propose that we do instead, since the canvas package is necessary when using the PDF.js library in Node.js environments and we support browsers/Node.js in the same builds?

[tamuratak]

One of options would be moving canvas into optionalDependencies from dependencies. Then, npm i pdfjs-dist will install canvas as a dependency by default, and npm will not stop installing pdfjs-dist even if installing canvas fails.

Users also can executenpm i --omit=optional pdfjs-dist if they want not to install canvas.

• https://docs.npmjs.com/cli/v8/configuring-npm/package-json#optionaldependencies

[Snuffleupagus]

So by using optionalDependencies we basically change an install-time error into a potential run-time error for some (hopefully small number of) Node.js users, while avoiding any issues for browser users? If so, I suppose that we can try that; please submit a patch.

[sunknudsen]

@tamuratak Thanks for raising flag… just hit use case on M1 Mac.

@Snuffleupagus, will #15655 makes it’s way to pdfjs-dist?

[timvandermeij]

Fixed in release 3.1.81.

[nikitakot]

The npm i --omit=optional pdfjs-dist doesn't seem to work. The canvas dependency is still installed and appears in node_modules and package-lock.json. I use electon.js and electron-rebuild to build my electron app and electron-rebuild tries to rebuild the canvas from the node modules which I don't event need.

[silverwind]

canvas module does not work inside worker threads, which are in use by testing frameworks like vitest.

Can it be dropped or be made optional so the consumer can provide it to pdf.js on-demand? At minimum, the require for it should be wrapped in a try-catch clause.

[bn3t]

For me it worked when doing:

npm i --omit=optional pdfjs-dist@3.5.141

Since, my issue was specifically when running unit tests combining vitest and jsdom, I also did:

npm i --omit=optional jsdom

[silverwind]

omit works (best set in .npmrc), but it's dangerous because it will omit all optional dependencies from all your dependencies, not just pdfjs-dist.

[bn3t]

At the end, I have to come back at what I've written in an above comment. --omit=optional didn't work as other dependencies were marked as optional (esbuild-*) but were necessary anyway. I am using another solution which also looks like a hack but seems to work. It comes from this SO answer: https://stackoverflow.com/a/73846274. It consists in adding this to package.json:

"overrides": {
    "canvas": "../_EXCLUDED_"
  }

Since canvas, is an optional dependency, an override to a non existing location is ignored silently.

[lucasgadams]

Is there any way to reduce the needed size of the canvas package? when I use pdfjs in a nextjs environment, the canvas package is like 48mb and the limit for Vercel is 50mb! This makes it incredibly difficult to build an app. No other package is even close to this size. Kind of pulling my hair out over this, i currently cant deploy my app. Any ideas?

[MattyBalaam]

I found a workaround to stop installing canvas if that might help? We add a new entry to the resolutions object in package.json for canvas:

https://github.com/mozilla/pdf.js/issues/16463

[net]

I wonder if using @napi-rs/canvas instead would be a good solution for both M1 and Vercel environments.

[jakepgoldman]

@net how would you go about replacing the canvas dep with the package you listed above?