Record selection changes in history (undo)

[ellatrix]

Description

Creates selection reducers in core/editor to track selection within the withHistory reducer.

I've also split isSelectionEnabled, isMultiSelecting, and initialPosition out of the blockSelection, as these are not tied to the selection state. Since the reducer then didn't contain anything but the start and end of the selection, I flattened the structure to state.selectionStart and state.selectionEnd. The reducers ended up being much simpler.

The following gif shows the result after two times undo:

How has this been tested?

Screenshots

Types of changes

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.

[ellatrix]

Phew, this passed now! It was not obvious from the errors what the cause was, but apparently it was resetting the selection when the provider didn't provide any selection, which is the case for previews. :)

[ellatrix]

So this is again ready for a final review.

[epiqueras]

Since #16932 was merged, we'll need to take a different approach here.

I think it should be pretty easy to make the selection a transient edit of the post entity just like .blocks:

gutenberg/packages/core-data/src/entities.js

Line 38 in 973448f

transientEdits: { blocks: true },

This makes them part of undo behavior, but not considered for change detection or persistence.

We can probably still keep all of the other changes that simplify the reducer.

[ellatrix]

@epiqueras Thanks for letting me know. What's the best place I can learn about the changes? I'll have a look through the code changes soon.

[epiqueras]

• Core Data: Add util for minimally modifying items. #16823
• Core Data: Add support for entity edits and undo history. #16867
• Core Data: Add support for autosaving entities. #16903
• Editor: Update the store to use Core Data entities. #16932

[ellatrix]

Closing in favour of #17824.