Image encoding API

[padenot]

#152 is the initial PR adding image decoding support, but image encoding needs to be added to the spec.

[dalecurtis]

Seems reasonable, the existing image encoding path only operates on canvas:
https://developer.mozilla.org/en-US/docs/Web/API/HTMLCanvasElement/toBlob

[talltyler]

Canvas.toBlob does not address any file format that supports animation. For static images this is fine but it would be incredibly useful to combine a bunch of VideoFrames into a GIF or animated PNG.

[dalecurtis]

FWIW, you can assemble an aPNG from multiple toBlob("image/png") calls IIUC. Your point stands for GIF though. The wrinkle is that UAs generally don't ship a GIF encoder already, so adding new formats isn't always easy.

[dalecurtis]

Since I was curious if it could actually be done, here's a demo assembling an APNG from PNG files for those curious: https://dalecurtis.github.io/apng-assemble/
https://github.com/dalecurtis/dalecurtis.github.io/tree/master/apng-assemble

[talltyler]

Thank you, this is truly very helpful.
I still think having an ImageEncoder could with a common interface that could make use of VideoFrames could be even more useful but for now this is better than what I'm currently doing.

[aboba]

@Djuffin @padenot Can we close this?

[Djuffin]

No progress and no plans on this issue for 3 years.