[PP-1] Re-create Image field widget on top of media entity

How might this impact #2113931: File Field design update: Upload field. ?

The new image widget design is here: https://www.drupal.org/node/2115469

About that, we can't implement the exact same field widget as core currently does. The alt text will be a problem since this is stored globally in media entities.

For this first widget it is probably best to just display the global alt text. We can discuss the best way to fix the 'alt text per instance' issue in a follow up.

Probably best to wait with this until #2831940: Create file field widget on top of media entity is done.

As per the roadmap (#2825215: Media initiative: Roadmap), this is postponed on #2831937: Add "Image" MediaSource plugin.

This issue has landed #2831937: Add "Image" MediaSource plugin and its unblocked now.

//Naveen

I think this is still blocked on #2831940: Create file field widget on top of media entity

Okay, postponed on #2831940: Create file field widget on top of media entity.

Adding MediaImageWidget based on the work @marcoscano and I have done on #2831940: Create file field widget on top of media entity.

In order to test this patch, please apply #2831940-119: Create file field widget on top of media entity.

Improvement on yesterday's work that handles the (admittedly unlikely) situation where a site builder sets an image media entity's source image field to require "alt" and/or "title". See required complementary change in #2831940-120: Create file field widget on top of media entity.

I don't think that's unlikely at all actually, isn't the alt field being required the default setting? And if it's not for image bundles then it probably should be, because that was an explicit decision that was made to ensure good accessibility.

@berdir, good points. My comment came off as more dismissive of the alt field's importance than I meant it to. I think I've been hyper-focused on getting the whole Media(File|Image)Widget setup working for the 80% use case, and lost sight of accessibility to some extent. In my defense, I am ensuring that the alt field works :)

Sure, I just meant to underline that supporting that is important because it *should* be the 80%/default use case and if it's not that now then we should have a separate issue to change that.

Did not mean to critize you (or anyone else) in any way.

@berdir no offense taken! It's absolutely helpful feedback.

Also, I just cleaned up the code a bit and added some testing. This patch includes the work from #18.

Please note that #2377747: Incorrect node create validation error when an invalid image is attached to a field has added an additional validation to the ImageWidget (i.e. checking that the image file is valid). Would that need to be ported here too.

SAme as #23, but for #1014816: Allow image fields to use any extensions the current image toolkit supports (instead of hard-coding jpg, png and gif only).

Since #2831940: Create file field widget on top of media entity is marked as wont fix, can we proceed with this?

We don't need to! :) The experimental Media Library module went into Drupal 8.6 and provides this functionality. I think we can close this issue as outdated.

#28, I don't see that Media Library 8.6 supports editing alt / title on the node edit page? "Replicate look & feel of the existing image field. Also keep support for alt/title and save them as field values on the media entity." so probably best not to close? Or am I missing something :-)