Re: clipboard events

On Tue, Jan 25, 2011 at 21:26, Hallvord R. M. Steen <>wrote:

> (Responding to multiple E-mails. Plead guilty to Ianesque behaviour there.
> Last draft of spec is
> On Fri, 24 Dec 2010 07:21:35 +0900, Paul Libbrecht <>
> wrote:
>  - this seems to support the insertion in the clipboard's data of other
>> types than what is currently commonly supported by browsers and the minimum
>> quoted there; this is good and important. I think, for example, that such
>> data as the iCal format would fit very well and be very useful here.
> It intends to, but this has two open issues:
> * I assume that many OS clipboard implementations have an enumerated list
> of "known" formats, I'm not sure if all OSes can handle a request to push
> "text/foobar" data to the clipboard. Does anyone know if we can rely on such
> functionality being truly cross-platform?

Platform capabilities vary.
- Windows will be unhappy if you use up all the custom clipboard formats
(~65535 or so). There is no way to release formats once registered.
- Mac uses UTIs which are strings but not MIME types.
- GTK+ seems to support arbitrary MIME types.
So for push support, Windows will be unable to natively support arbitrary
string types.

When pulling data from the clipboard, I wonder if it may also be a bad idea
to expose all the native types. I was working on a patch to do this in
WebKit, and it turns out some of the native types leak information about
filesystem paths when files are involved in the dragging/paste operation.

> * There is not yet a clear way to push multi-part or alternate formats to
> the OS clipboard from JS. To use something like iCal, I guess best practise
> would be to push one human-readable text/plain string for target software
> without iCal support, and one alternate entry in iCal format. I guess that
> can be done with
>  DataTransferItem add(in DOMString data, in DOMString type);
> I.e. spec for copy event would be
> * default action: copy any document selection
> * if default action is prevented: push data in drag data store (as
> manipulated by setData() or items.add()) to clipboard, probably mapping
> certain known values to native clipboard formats while doing so.

If the default action is prevented and no data was added to the drag data
store, does that imply the clipboard should be cleared?


Received on Wednesday, 26 January 2011 20:40:03 UTC