Pickling for Async Clipboard API

[snianu]

Request for Mozilla Position on an Emerging Web Specification

• Specification Title: Pickling for Async Clipboard API

• Specification or proposal URL: https://github.com/w3c/editing/blob/gh-pages/docs/clipboard-pickling/explainer.md

• Caniuse.com URL (optional):

• Bugzilla URL (optional): https://bugzilla.mozilla.org/show_bug.cgi?id=860857

• Mozillians who can provide input (optional): @smaug----

Other information

There have been discussions on Pickling Clipboard API during TPAC and also while discussing Raw Clipboard API.
Slides: https://docs.google.com/presentation/d/1_fAgL54D0whQ497G8iL0K2kKpxiWDr3M7gXXSIS76II
Editing TF Minutes: https://lists.w3.org/Archives/Public/public-editing-tf/2020Oct/0017.html
Chrome Status entry: https://chromestatus.com/feature/5649558757441536
Design Doc: https://docs.google.com/document/d/1afc45MQuwxEWgoUeJCO-sOWRSzs31V4JS-kKXJNMTXw/edit?usp=sharing

Some notes about Mozilla's support for custom formats.

• It currently has an implementation to support custom format, but that is not standardized.
• This proposal just adds an option to include custom formats via ClipboardItemOption so the formats don't get written into the clipboard without web authors explicitly specifying the custom formats. This also allows for creating unsanitized pickled formats even for well-known mime types

Thanks!

[evilpie]

I think before specifying support for custom formats it would be good to specify the subset of other formats that are actually supported.

We are interested in the async clipboard API, but the current specification is under-specified and differs between Webkit and Blink, which currently blocks us from enabling at least clipboard.write. It would be great if we could make progress on w3c/clipboard-apis#135 first.

[snianu]

@evilpie I've responded to w3c/clipboard-apis#135 issue, but I think custom format support is sort of orthogonal to other standard formats. Custom format is already supported by major browsers via DataTransfer object(e.g. https://jsfiddle.net/gked/5xo1whye/4) and we are trying to standardize this via Async Clipboard APIs. Particularly we are interested in getting feedback for:
(a) The shape of the API to read/write the pickled data.
(b) The format of pickled data on the native clipboard.
Please let us know if you have any thoughts on the proposal.

[annevk]

It's a problem to be asked to evaluate new stuff when the older new stuff isn't written down/maintained to the point where it can be implemented. Sure, it's a somewhat separable API piece, but there's a larger problem here that needs addressing first as we don't want this to compound.

[gked]

Thanks, @annevk. We've started discussing this over on web editing front - w3c/editing#305.
I agree that we could specify mime types. At least the ones that are non-controversial and having cross-browser support.

Given that you also agree it is somewhat tangential to pickling, we were hoping to get a yay/nay on the current proposal so we know how to proceed with the work and we'll address adding supported MIME types to the async clipboard spec shortly after the pickling format goes in.

Thoughts?

[annevk]

The problem goes a lot further than that, no? E.g., looking at https://w3c.github.io/clipboard-apis/#clipboard-interface there's an entire object there (ClipboardItem) that is not defined in the slightest. And that object seems somewhat important for the case at hand.

In the abstract pickling is a good idea and something we have suggested we should do for a while. So from that perspective I'm glad we all landed on the same page, but I feel like we have more fundamental problems to tackle first such as getting the specification maintained and adding cross-browser automated test infrastructure.

[snianu]

@annevk ClipboardItem is described here. I'm not sure what information is missing there though. We are discussing some changes related to clipboard formats in w3c/editing#305 issue. It'd be great if Mozilla can participate in those discussions as well.

[annevk]

It's not? Where is the definition of its constructor or any of its members for instance?

[snianu]

Sorry, but I'm still confused. Below is the description of the interface and its members copy-pasted from here:

typedef Promise<ClipboardItemDataType> ClipboardItemData;

callback ClipboardItemDelayedCallback = ClipboardItemData ();

[Exposed=Window] interface ClipboardItem {
  constructor(record<DOMString, ClipboardItemData> items,
    optional ClipboardItemOptions options = {});
  static ClipboardItem createDelayed(
      record<DOMString, ClipboardItemDelayedCallback> items,
      optional ClipboardItemOptions options = {});

  readonly attribute PresentationStyle presentationStyle;
  readonly attribute long long lastModified;
  readonly attribute boolean delayed;

  readonly attribute FrozenArray<DOMString> types;

  Promise<Blob> getType(DOMString type);
};

enum PresentationStyle { "unspecified", "inline", "attachment" };

dictionary ClipboardItemOptions {
  PresentationStyle presentationStyle = "unspecified";
};

[annevk]

That's IDL. IDL needs to be accompanied by prose that defines how things work. E.g., https://dom.spec.whatwg.org/#interface-text has the Text interface and https://dom.spec.whatwg.org/#dom-text-text defines the constructor for it (linked from the IDL).

[snianu]

@annevk @mbrodesser we are committed to improving the existing async clipboard spec. Any chance you could comment on the Pickling API proposal?

[annevk]

As per w3c/clipboard-apis#162 (comment) I still think the proposal needs further work before it can be evaluated properly.

[mbrodesser]

@annevk @mbrodesser we are committed to improving the existing async clipboard spec. Any chance you could comment on the Pickling API proposal?

I'd like to finish w3c/clipboard-apis#158 first. AFAIU, pickling comes on top of it.

[zcorpan]

It seems the spec is now in a better shape with IDL members properly defined. e.g. https://w3c.github.io/clipboard-apis/#clipboard-item-interface

The explainer for Pickling has moved to https://github.com/w3c/editing/blob/gh-pages/docs/clipboard-pickling/explainer.md#pickling-for-async-clipboard-api

[snianu]

I have also made the required spec changes for this feature. To merge these changes, I need someone who has write access to the repo to sign-off on the PR.