[whatwg] Drag-and-drop feedback

Daniel Cheng dcheng at google.com
Mon Feb 22 18:06:08 PST 2010


Several questions about the proposal:
How does DataTransferItems interact with the original DataTransfer object?
I'm assuming changes in one should be reflected in the other. If that's the
case, what should happen if I do this:
dataTransfer.items.add(fileData);
dataTransfer.getData(mimeTypeForFile);

How come there's no DataTransferItems.get(type) method?

DataTransferItem provides richer metadata than is available through the
native drag-and-drop interface on most platforms. When dragging data from a
non-DOM application, how do you extrapolate the metadata to fill in the
type/binary fields?

Daniel

On Mon, Feb 22, 2010 at 3:51 PM, Ian Hickson <ian at hixie.ch> wrote:

> On Thu, 4 Feb 2010, Ian Hickson wrote:
> > On Sat, 23 Jan 2010, Eduard Pascual wrote:
> > >
> > > Would it be possible to provide a list of "drag items" (to call them
> > > somehow) instead of, or in addition to, the current info provided by
> > > the DataTransfer object?
> >
> > That's a pretty good idea. I think we should probably do this when we
> > add more types to the DataTransfer object.
>
> Some engineers at Google discussed this a bit and came up with the
> following proposal:
>
>   dataTransfer.items = DataTransferItems
>
>    DataTransferItems.length
>                     .getItem(n) = DataTransferItem
>                     .add(stringData, type)
>                     .add(blobData)
>                     .add(fileData)
>                     .add(dataTransferItem)
>                     .clear()
>
>    DataTransferItem.kind = 'string', 'file', 'blob', ...
>                    .type = MIME type
>                    .binary = boolean
>                    .getTextData(function callback (data)) - throws if
> binary is true
>                    .getBlob() - returns File or Blob
>
> When we add promises later, this can easily be extended to support that as
> well (basically, just by adding a new add() method for the promise case).
>
> I've put this into the comment in the spec, but haven't specced it. If any
> browser vendors want to try implementing this or something like it, any
> reports of implementation experience would be very useful. Please prefix
> the "items" attribute with some unique string like "webkitItems" or
> "geckoItems" so that it doesn't clash with the spec when we do add
> something like this!
>
> Cheers,
> --
> Ian Hickson               U+1047E                )\._.,--....,'``.    fL
> http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
> Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
>
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