Hey, On Tue, Dec 22, 2015 at 1:36 PM, Jonas Ådahl <[email protected]> wrote: > On Tue, Dec 22, 2015 at 12:20:35PM +0100, Carlos Garnacho wrote: >> Hey!, >> >> On Tue, Dec 22, 2015 at 4:12 AM, Jonas Ådahl <[email protected]> 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 <[email protected]> >> >> >> >> 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 <[email protected]> >> >> Reviewed-by: Michael Catanzaro <[email protected]> >> >> Reviewed-by: Mike Blumenkrantz <[email protected]> >> > >> > >> > >> >> --- >> >> 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. > > This is much better I think. What I think can be added is the > event/request flow for "ask". Here it sounds like for "ask" after the > destination sent the last wl_data_offer.set_actions with the chosen > action(s), it still need to do a roundtrip to make sure that maybe > emitted wl_data_offer.action is received. It'd be more clear if this is > actually spelled out. > > Or should it be like that? The wl_data_offer do have the information it > needs to make a decision (it has the wl_data_source's actions, and the > compositor will have no say anyway as you wrote above), so we could > avoid the roundtrip by just having the client make the decision while > the compositor just acts as a guard and terminates a client that tries > to set more than one action or any action not supported by the data > source.
Yeah, right. As you say the drag dest can preempt the final action through wl_data_offer.source_actions, that's also in fact useful for "ask" actions, as otherwise you have to probe the available actions. I've added the following blurb, again to wl_data_offer.action: Upon "ask" actions, the drag-and-drop destination is expected to possibly choose different a different action and/or mime type, based on wl_data_offer.source_actions and finally chosen by the user (e.g. popping up a menu with the available options). The final wl_data_offer.set_action and wl_data_offer.accept requests must happen before the call to wl_data_offer.finish. Cheers, Carlos _______________________________________________ wayland-devel mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/wayland-devel
