First-line indent slider option for paragraphs

[kosiew]

What

A slider option in the paragraph's block menu to enable first-line-only indenting (like a tab in a classic document)

Why

I've run across a few people lately who've requested this. Some people like the classic formatting look (like a book). Others may be used to writing in Word docs (where a tab or margin adjustment to top-line indents are readily available).

In any case, there should be an easy way to toggle this for non-technical users. It's a very "front-facing, writing heavy" feature that people are used to having readily available. Making it a somewhat technical workaround with CSS and classes only enforces that "You can do anything with WordPress, as long as you ave a technical background and can write CSS." This aims to break that mold.

How

CURRENTLY

You can achieve a top-line-only indent a couple ways.

1. Custom HTML - Add custom HTML block, then add paragraph tags and include the space-characters " " or " " or " " which are rendered as different levels of spacing. <p>&emsp; This is the indented first line only.</p>
2. Custom CSS - EITHER Switching to code editor and adding <p style="text-indent: 50px;"> to your intended paragraph. OR adding in your Custom CSS section p { text-indent: 1em; } (which will indent ALL paragraph blocks across your site - so, easy to implement and update to a different value, but a pain to have it apply to all paragraph blocks everywhere). Alternative is to create a custom class like "book-styling-paragraph" and then label all paragraphs you want indented like this with that class name.

References

• https://developer.mozilla.org/en-US/docs/Web/CSS/text-indent
• https://stackoverflow.com/questions/9792849/how-to-insert-spaces-tabs-in-text-using-html-css#:~:text=Follow-,answered,-Sep%202%20%2718

FUTURE

A slider in the block menu of the paragraph block you can easily toggle a first-line-only indent.

Design considerations

• A little clumsy to have to toggle each paragraph you want indented, especially if you're writing a long piece (but better option than indenting all p blocks across your website)
• A way to highlight multiple paragraphs and toggling it in one place changes all of the blocks
• A custom shortcut keystroke which acts like a tab in Word, but in fact toggles this menu option in the paragraph block menu (ie: SHIFT-tab [toggles indent menu option] "Hello world...")
• When FSE editing comes around, you could change one specific parameter of the styling of that first-line-only indent making it bigger or smaller

References

• Move the paragraph indent style to the first paragraph of every container themes#4481 Which came up with a workaround to indent all only-first paragraph blocks, but ended up with a lot of unintended side-effects and complications. A toggle would make this really easy as one manual action per new page/post

[skorasaurus]

related, previous discussion about this: #28524 and #14554

[jordesign]

Closing this as it has been long dormant, and also a duplicate of #37462