[PATCH wayland] protocol: Improve data source notification around DnD progress

[Carlos Garnacho]

Hi Mike,

On Fri, Oct 16, 2015 at 5:58 PM, Mike Blumenkrantz <zmike at samsung.com> wrote:
> On Fri, 16 Oct 2015 16:53:28 +0100
> Daniel Stone <daniel at fooishbar.org> wrote:
>
>> Hi,
>>
>> On Wednesday, 30 September 2015, Carlos Garnacho <carlosg at gnome.org>
>> wrote:
>>
>> > Currently, there's no means for the DnD origin to know whether the
>> > destination is actually finished with the DnD transaction, short of
>> > finalizing it after the first transfer finishes, or leaking it
>> > forever.
>> >
>> > But this poses other interoperation problems, drag destinations
>> > might be requesting several mimetypes at once, might be just poking
>> > to find out the most suitable format, might want to defer the
>> > action to a popup, might be poking contents early before the
>> > selection was dropped...
>> >
>> > In addition, data_source.cancelled is suitable for the situations
>> > where the DnD operation fails (not on a drop target, no matching
>> > mimetypes, etc..), but seems undocumented for that use (and unused
>> > in weston's DnD).
>> >
>> > In order to improve the situation, the drag source should be
>> > notified of all stages of DnD. In addition to documenting the
>> > "cancelled" event for DnD purposes, The following 2 events have
>> > been added:
>> >
>> > - wl_data_source.drop_performed: Happens when the operation has been
>> >   physically finished (eg. the button is released), it could be the
>> > right place to reset the pointer cursor back and undo any other
>> > state resulting from the initial button press.
>> > - wl_data_source.drag_finished: Happens when the destination side
>> > destroys the wl_data_offer, at this point the source can just
>> > forget all data related to the DnD selection as well, plus
>> > optionally deleting the data on move operations.
>> >
>> > Signed-off-by: Carlos Garnacho <carlosg at gnome.org <javascript:;>>
>>
>>
>>  Mike had a look at this from EFL - CCing him.
>>
>> Cheers,
>> Daniel
>
> Hi,
>
> Having reviewed this, and also having fully implemented the current DND
> protocol, I think that this is a good idea and would be a worthwhile
> addition. I have no suggestions for modifications or trivial
> bikeshedding.

I didn't get to say, thanks very much for this. Is it ok to assume a
Reviewed-by from you for the protocol patches? I'm very much looking
forward to seeing these gaps closed in the protocol, and hopefully a
few more R-bs can leverage this in.

Cheers,
  Carlos