PR: Acknowledge inline widgets

[jodator]

Suggested merge commit message (convention)

Other: Introduce inline widget sample. Closes ckeditor/ckeditor5#1096.

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Additional information

• 🎉 inline widgets
• all required changes gathered under the ckeditor5#t/1096 branch:
  • engine: PR
  • enter: PR
  • typing: PR

ps.: WIP as other PRs requires tests

[jodator]

@Reinmar Finally done - all issues should be resolved. The go-to is a manual test with placeholder inline widget POC.

Works:

• typing after inline widget
• inline widget selection
• fake selection on inline widget (selection was set in text nodes around IW in the view. I've fixed that by introducing default modelToView helper in mapper (added by editing).

The build is green on CI.

[scofalik]

I've added mapper callback for non-empty view element -> empty model element mapping. I've modified the manual sample to use it. Also, {...} placeholder brackets are now inserted in view instead of CSS, which caused problems.

[Reinmar]

I'm wondering – shouldn't that placeholder be selected by insertContent()? If it was a block, it would be. However, if it was a block, the case is slightly different because the selection should not be set after it. So selecting it is the most reasonable solution. In case of inline objects, we can set the selection after this element (and we do that now). WDYT?

cc @scofalik @jodator

[scofalik]

From UX perspective, I think that setting the selection after the inline-widget is defensible. You insert the widget and maybe want to go on with writing.

[Reinmar]

Actually, I can asnwer this myself – pasting should not select the placeholder, so should not insertContent().

[scofalik]

BTW. I am missing one here thing, which I forgot to add. The widget has no label, resulting in no description for fake selection. I think we should encourage people to add these so it should be in a guide and I guess in the manual sample too.