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Re: Question about implementing DataTransfer.addElement

From: Daniel Cheng <dcheng@chromium.org>
Date: Fri, 7 Oct 2011 15:18:22 -0700
Message-ID: <CAF3XrKoNVhZRpq3zzpLm5sfM+iigYCjLTeVgFYrDb5Wf9z_XaQ@mail.gmail.com>
To: James Robinson <jamesr@google.com>
Cc: "Tab Atkins Jr." <jackalmage@gmail.com>, public-webapps <public-webapps@w3.org>
The way drag images work today is we take a snapshot and then hand it off to
the system. To support addElement(), we'd need:
1. Some way to detect when that element has changed in visual appearance so
we can update the drag image.
2. Some way to actually update the drag image in the middle of a drag. This
is (as far as I'm aware) impossible with the documented interface for
Windows DnD, and I'm not aware of an undocumented way to do it either.

I'm more concerned about the latter, and while I don't believe it's
impossible to solve, I think it would be difficult to make performant in
case of things like video or other embedded content.


On Fri, Oct 7, 2011 at 15:01, James Robinson <jamesr@google.com> wrote:

> On Fri, Oct 7, 2011 at 2:56 PM, Tab Atkins Jr. <jackalmage@gmail.com>wrote:
>> On Fri, Oct 7, 2011 at 2:45 PM, Daniel Cheng <dcheng@chromium.org> wrote:
>> > For technical reasons, animating the drag image is non-trivial and not
>> > likely to be implemented in the near future, if it is ever implemented.
>> I would think that it's basically identical, technically, to
>> implementing the element() function from CSS Image Values, which I
>> believe we're planning to do.
> Not quite.  With the element() function the 'live copy' still lives in the
> page and renders the same way everything else does.  My understanding (and
> Daniel can correct me if I'm wrong) is that drag images do not render the
> same way due to platform integration concerns and so the technical cost for
> the two is fairly different.
> - James
>> ~TJ
Received on Friday, 7 October 2011 22:18:49 UTC

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