add indent/outdentBlocks commands

[ianstormtaylor]

Do you want to request a feature or report a bug?

Feature.

What's the expected behavior?

There are lots of use cases that make use of "indenting" and "outdenting". The native beforeinput events even tap into them too. I think it would be good to standardize change.indentBlocks and change.outdentBlocks, so that other plugins can build on them. For example, a quote behavior plugin could listen for 'indentBlocks' and do quote-specific behaviors.

By default, I think it should look for the top-level blocks and double nest them. Such that this:

<quote>
  <paragraph>
    <anchor />one
  </paragraph>
  <paragraph>
    two<focus />
  </paragraph>
</quote>

Would turn into:

<quote>
  <quote>
    <paragraph>
      <anchor />one
    </paragraph>
    <paragraph>
      two<focus />
    </paragraph>
  </quote>
</quote>

[Dundercover]

I think there are quite a few different approaches people take to denote indentation. Those I've guessed are the most used:

• Double nest single block. Like you described above. Could also be leaf block.
• Double nest multiple blocks. Like with html ul/ol + li.
• Additional data on block node. Like { indent: 2 } or something.

Default behaviour of this command wouldn't be able to handle all of these but support for them would be nice somehow.

Maybe we could make a plugin which you could configure for your use case? (If it doesn't already exist such plugin?)

[ianstormtaylor]

Nice, thanks @Dundercover! I think the ul/ol/li case is too complex to try to handle in core well, at least from my experience. Maybe there's a different way of thinking about that one that my brain's not finding though. And for the data on blocks, that one seems easy enough for people to override.

I think it's a good question though to ask whether the default behavior should exist at all, or whether it should be be standardizing the "indent/outdent" command intent names for people to use in all cases.

[ianstormtaylor]

As of #3093 (which was just merged), I believe this issue is no longer applicable, because a lot has changed. I'm going through and closing out any potential issues that are not out of date with the overhaul. Thanks for understanding.