Hey!, On Tue, Dec 22, 2015 at 4:12 AM, Jonas Ådahl <jad...@gmail.com> wrote: > On Tue, Dec 22, 2015 at 02:33:33AM +0100, Carlos Garnacho wrote: >> These 2 requests have been added: >> >> - wl_data_source.set_actions: Notifies the compositor of the available >> actions on the data source. >> - wl_data_offer.set_actions: Notifies the compositor of the available >> actions on the destination side, plus the preferred action. >> >> Out of the data from these requests, the compositor can determine the action >> both parts agree on (and let the user play a role through eg. keyboard >> modifiers). The chosen option will be notified to both parties >> through the following two requests: >> >> - wl_data_source.action >> - wl_data_offer.action >> >> In addition, the destination side can peek the source side actions through >> wl_data_offer.source_actions. >> >> Compared to the XDND protocol, there's two notable changes: >> >> - XDND lets the source suggest an action, whereas wl_data_device lets >> the destination prefer a given action. The difference is subtle here, >> it comes off as convenience because it is the drag destination which >> receives the motion events (unlike in X) and can perform action updates. >> >> The drag destination seems also in a better position to update the >> preferred action based on things like the data being transferred, the >> place being dropped, and whether the drag is client-local. >> >> - That same source-side preferred action is used in XDND to convey the >> modifier-induced action to the drag destination, which would then ack >> it, or reply with another action that's accepted (or none), this makes >> the XdndPosition/XdndStatus messaging very verbose, and synchronous >> because the drag source always needs to know the latest status/action >> for every position+action sent. >> >> Here it's the compositor which takes care of modifiers and matching >> available/accepted actions, this allows for the signaling to happen >> only whenever the actions/modifiers change for real. >> >> Roughly based on previous work by Giulio Camuffo <giuliocamu...@gmail.com> >> >> Changes since v5: >> - Applied rewording suggestions from Jonas Ådahl. Dropped slot reservation >> scheme for actions. Fixed indentation and other minor formatting issues. >> >> Changes since v4: >> - Minor rewording. >> >> Changes since v3: >> - Splitted from DnD progress notification changes. >> - Further rationales in commit log. >> >> Changes since v2: >> - Renamed notify_actions to set_actions on both sides, seems more consistent >> with the rest of the protocol. >> - Spelled out better which events may be triggered on the compositor side >> by the requests, the circumstances in which events are emitted, and >> what are events useful for in clients. >> - Defined a minimal common ground wrt compositor-side action picking and >> keybindings. >> - Acknowledge the possibility of compositor/toolkit defined actions, even >> though none are used at the moment. >> Changes since v1: >> - Added wl_data_offer.source_actions to let know of the actions offered >> by a data source. >> - Renamed wl_data_source.finished to "drag_finished" for clarity >> - Improved wording as suggested by Bryce >> >> Signed-off-by: Carlos Garnacho <carl...@gnome.org> >> Reviewed-by: Michael Catanzaro <mcatanz...@igalia.com> >> Reviewed-by: Mike Blumenkrantz <zm...@samsung.com> > > > >> --- >> protocol/wayland.xml | 122 >> +++++++++++++++++++++++++++++++++++++++++++++++++++ >> 1 file changed, 122 insertions(+) >> >> diff --git a/protocol/wayland.xml b/protocol/wayland.xml >> index ae5ef21..001d811 100644 >> --- a/protocol/wayland.xml >> +++ b/protocol/wayland.xml >> @@ -486,6 +486,55 @@ >> wl_data_offer.destroy after this one. >> </description> >> </request> >> + >> + <request name="set_actions" since="3"> >> + <description summary="set the available/preferred drag-and-drop >> actions"> >> + Sets the actions that the destination side client supports for >> + this operation. This request may trigger the emission of >> + wl_data_source.action and wl_data_offer.action events if the compositor >> + needs changing the selected action. >> + >> + This request can be called multiple times throughout the >> + drag-and-drop operation, typically in response to wl_data_device.enter >> + or wl_data_device.motion events. >> + >> + This request determines the final result of the drag-and-drop >> + operation. If the end result is that no action is accepted, >> + the drag source will receive wl_drag_source.cancelled. >> + </description> >> + <arg name="dnd_actions" type="uint"/> >> + <arg name="preferred_action" type="uint"/> >> + </request> >> + >> + <event name="source_actions" since="3"> >> + <description summary="notify the source-side available actions"> >> + This event indicates the actions offered by the data source. It >> + will be sent right after wl_data_device.enter, or anytime the source >> + side changes its offered actions through wl_data_source.set_actions. >> + </description> >> + <arg name="source_actions" type="uint"/> >> + </event> >> + >> + <event name="action" since="3"> >> + <description summary="notify the selected action"> >> + This event indicates the action selected by the compositor after >> + matching the source/destination side actions. Only one action (or >> + none) will be offered here. >> + >> + This event can be emitted multiple times during the drag-and-drop >> + operation, mainly in response to source side changes (through >> + wl_data_source.set_actions), destination side changes (through >> + wl_data_offer.set_actions), and as the pointer enters/leaves >> + surfaces. >> + >> + Compositors may also change the selected action on the fly, mainly >> + in response to keyboard modifier changes during the drag-and-drop >> + operation. >> + >> + The most recent action received is always the valid one. > > How can we describe this more precisely? "most recent" is ambigous, and > it makes it seem possible to have the destination and client o have > different ideas of what action is actually used. > > I suppose it is a bit problematic. For "move"/"copy" it's simpler, > because no changes will be made after wl_data_device.drop and that > event could act as a barrier, but for "ask" it is tricky. > > When "ask" is used, I assume the destination will call > wl_data_offer.set_actions to something other than "ask" (this doesn't > seem spelled out anywhere btw, should probably describe what "ask" > actually is). After this is done, should the compositor reply with the > actual action after having made sure the source supports the newly set > action, with the client waiting for a reply. Or should the destination > make sure to choose from one of the "source_actions" actions (while the > compositor would terminate any client choosing an unavailable action)? > >> + </description> >> + <arg name="dnd_action" type="uint"/> >> + </event> >> </interface> >> >> <interface name="wl_data_source" version="3"> >> @@ -542,6 +591,9 @@ >> - The drag-and-drop operation was performed, but the drop destination >> did not accept any of the mimetypes offered through >> wl_data_source.target. >> + - The drag-and-drop operation was performed, but the drop destination >> + did not select any action present in the mask offered through >> + wl_data_source.action. >> - The drag-and-drop operation was performed but didn't happen over a >> surface. >> - The compositor cancelled the drag-and-drop operation (e.g. compositor >> @@ -557,6 +609,16 @@ >> >> <!-- Version 3 additions --> >> >> + <request name="set_actions" since="3"> >> + <description summary="set the available drag-and-drop actions"> >> + Sets the actions that the source side client supports for this >> + operation. This request may trigger a wl_data_source.action event >> and >> + wl_data_offer.action events if the compositor needs changing the >> + selected action. >> + </description> >> + <arg name="dnd_actions" type="uint"/> >> + </request> >> + >> <event name="dnd_drop_performed" since="3"> >> <description summary="the drag-and-drop operation physically >> finished"> >> The user performed the drop action. This event does not indicate >> @@ -576,8 +638,34 @@ >> The drop destination finished interoperating with this data >> source, the client is now free to destroy this data source and >> free all associated data. >> + >> + If the action used to perform the operation was "move", the >> + source can now delete the transferred data. >> </description> >> </event> >> + >> + <event name="action" since="3"> >> + <description summary="notify the selected action"> >> + This event indicates the action selected by the compositor after >> + matching the source/destination side actions. Only one action (or >> + none) will be offered here. >> + >> + This event can be emitted multiple times during the drag-and-drop >> + operation, mainly in response to source side changes (through >> + wl_data_source.set_actions), destination side changes (through >> + wl_data_offer.set_actions), and as pointer enters/leaves surfaces. >> + >> + Compositors may also change the selected action on the fly, mainly >> + in response to keyboard modifier changes during the drag-and-drop >> + operation. >> + >> + The most recent action received is always the valid one. > > Here as well I'd still like to see something more like "the last action > received before X" to describe what will be the final action. I guess > it's the last .action event emitted before .send (or .finished if no > data transfer was made for some odd reason)?
Oh, right, this didn't get much more verbosity... Right, since the action is to take effect in wl_data_source.dnd_finished, it would be the last one received at that point, so if a drag-and-drop operation starts as "ask", and the user selects "move", the action that must take effect on .dnd_finished is indeed "move". I've locally added the following blurb to wl_data_source.action: The most recent action received is always the valid one. The chosen action may change alongside negotiation (e.g. an "ask" action can turn into a "move" operation), so the effects of the final action must be always applied in wl_data_offer.dnd_finished. And this one to wl_data_offer.action: The most recent action received is always the valid one. Prior to receiving wl_data_device.drop, the chosen action may change (e.g. due to keyboard modifiers being pressed). At the time of receiving wl_data_device.drop the drag-and-drop destination must honor the last action received. Action changes may still happen after wl_data_device.drop, especially on "ask" actions, where the drag-and-drop destination may choose another action afterwards. Action changes happening at this stage are always the result of inter-client negotiation, the compositor shall no longer be able to induce a different action. Cheers, Carlos _______________________________________________ wayland-devel mailing list wayland-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/wayland-devel