[whatwg] more drag/drop feedback

Thomas Broyer t.broyer at gmail.com
Wed Jun 18 14:31:48 PDT 2008

On Wed, Jun 18, 2008 at 4:46 PM, Neil Deakin wrote:
> The initDragEvent/initDragEvent methods take a DataTransfer as an argument.
> Is it expected that the DataTransfer to use here can be created with 'new
> DataTransfer'?
> IE and Safari allow a no-argument form of clearData as well which clears all
> formats.

FWIW, Adobe AIR's Clipboard (which is equivalent to the DataTransfer
object) has a clear() no-argument method.


> The description for the 'types' property implies that this should be a live
> list. Why?

Maybe so that you can keep a reference to it while setData/clearData
is being called? But couldn't you just keep a reference to the
DataTransfer object? It seems that IE doesn't have such a property.
Adobe AIR's WebKit does, but how about Safari?

> The clearData, setData and getData methods should clarify what happens if an
> empty format is supplied.

For my personal culture, what happens in IE and Safari?

> I still don't understand the purpose of the addElement method.

I think addElement is there to allow e.g. "dialog boxes" where the box
can be dragged using its "title bar": only the title-bar is draggable
but ondragstart it adds the whole dialog box to the list of what is
being dragged...

> Either this
> should be removed or there should be clarification of the difference between
> addElement and setDragImage

setDragImage is only about the "drag feedback", not "what is being
dragged", if I understand correctly...

> Previously, I said that DragEvents should be UIEvents. I think they should
> instead inherit from MouseEvent.

FWIW, NativeDragEvent in Adobe AIR inherits MouseEvent.

> We have a need to be able to support both dragging multiple items, as well
> as dragging non-string data, for instance dragging a set of files as a set
> of File objects (see http://www.w3.org/TR/file-upload/) from the file system
> onto a page.

That would be new data formats.
That's how Adobe AIR solved the problem. They added a Bitmap and File
list data formats, for which getData returns AIR-specific objets (a
BitmapData and an array of File objects respectively)

> For this, we would also like to propose methods like the following, which
> are analagous to the existing methods (where Variant is just any type of
> object):

I don't see a real need for them (others didn't need them while
providing the same features) and they wouldn't be backwards compatible
with IE and Safari, while AFAIK the current draft is.

Thomas Broyer

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