Allow an HTMLCanvasElement as source for the image

[StephanBijzitter]

I already have a canvas and currently convert it into a base64 png, give it to vibrant and it then draws it on a canvas once more. This seems a bit redundant.

[maxcr]

Canvas operations are cheap since they are done on the GPU and not CPU. If your demographic is mainly really old android and IE then I guess you could rewrite it to merge the two canvas operations somehow but if were talking amount of milliseconds decreased on compute time it would be a negligible performance gain for anything made after 2012.

[StephanBijzitter]

If your demographic is mainly really old android and IE

Nail. Head. 😅

[maxcr]

I mean it seems that the WebAssembly implementation would solve the issue as that is the most performant state. Is the browser versions supported too old for WASM? If that's the case, it's going to take a lot of work but I'll take a look as soon as I figure out some other stuff.

[StephanBijzitter]

The only browser we have to support that doesn't support WASM is IE11 (sadly that's still a large minority of our users). I'll see if I can find some time to work on HTMLCanvasElement as input, but it could take a few months 😅

[maxcr]

I'll see about cooking up a patch for you buddy. Do you mind hosting your code somewhere for me so I can see how you're doing everything?

[StephanBijzitter]

Apologies for the late response, there's not really a way for me to host a sample repo as the codebase is a tad old and has a lot of external dependencies.

However in the end it's just a <canvas> element being painted on using FabricJS. They've got a lot of demos, perhaps those can be used instead? http://fabricjs.com/demos/

[crutchcorn]

This seems like a logical feature request to me. @maxcr, has there been any work done by you on this subject matter? We'd love pull requests and I could help out with anything you might have. We're currently moving new development towards the develop monorepo structure, but if you already have code written for master, I can migrate that code manually like we did for #82