Add "Paste as plain text" feature

[Alspb]

Is there an existing issue for this?

• I have searched the existing issues

Use case

It would be great to have "Paste as plain text" feature, as e.g. TextField on Android has.
Sometimes format is not needed, like when text is copied from browser.
Also, this should help avoid misunderstanding on when formatted or plain text is pasted, see #1772.

Proposal

Implement "Paste as plain text" feature and add it to the context menu for pasting. Maybe there should be an option on whether "Paste as plain text" should be included into that menu or not.

[Alspb]

It looks like to paste plain text one should disable the following code blocks from quill_controller.dart:

if (await _pasteHTML()) {
    updateEditor?.call();
    return true;
}

_applyPasteStyleAndEmbed(insertedText, index, containsEmbed);

But adding "Paste as plain text" to the context menu is not that straightforward, since the menu is implemented using EditableText.getEditableButtonItems.

[singerdmx]

@ellet0 Do you have any suggestion?

[ellet0]

If the user paste using the paste button above the keyboard, it should alwats paste as text. This behavior is specific to Android and will apply to all apps. As for the paste as plain text, we could also add the option to always paste as plain text and disable rich text pasting feature.

Notice that if you don't use flutter_quill_extensions, it will be displayed by default.

As for paste as plain text, it's might not be common or known by users, I would suggest having this option only if rich text paste is available.