Safari paste handling and Clipboard API

[dylans]

Description

A recent Safari update seems to have blocked all of Slate's attempts to append our syntax tree to application/x-slate-fragment. Previously this worked but would exclude files.

Sandbox/Steps

Any slate example shows an empty application/x-slate-fragment when pasting.

Expectation

We can control what gets pasted. Currently we're falling back to HTML which isn't great for void elements that have behavior not contained in html.

Environment

• Slate Version: Any
• Operating System: macOS, probably iOS
• Browser: Safari

Context

We probably need to switch to the newer clipboard api for Safari, though it's annoying in that it asks for user approval. See various links in #4465 (comment)

[IMSupperkaka]

same problem

[jdmanabat]

Currently, we are having an issue when pasting bullet and number lists in Safari. Do you think it's related to this?

[dylans]

Currently, we are having an issue when pasting bullet and number lists in Safari. Do you think it's related to this?

What type of issue?

[jdmanabat]

Currently, we are having an issue when pasting bullet and number lists in Safari. Do you think it's related to this?

What type of issue?

When pasting the copied bullet or numbered lists the HTML tags are removed.

[Nikhil22]

When I paste plain text with line breaks in Safari, Slate does not honor the line breaks. End result is all one block of text.

[dylans]

Safari has progressively made the old copy/paste API less usable, a strong to push to use the newer API (which requires user consent). We need to implement that in 2023 to solve a number of problems with copy/paste in Safari.

[Nikhil22]

@dylans Sounds good. If you or the team need any help, I'm happy to contribute in any way I can.

[12joan]

The Clipboard API doesn't require prompting for permission when writing to the clipboard from an event handler, only when reading it outside of a paste event. However, it won't work for copying application/x-slate-fragment data in Safari, since all major browsers only allow a limited set of data types when writing with Clipbard.write(). See https://webkit.org/blog/10855/.

I don't think there are any APIs that allow us to copy application/x-slate-fragment in Safari.