Copyright 2018 Mike Blumenkrantz Copyright 2018 Samsung Electronics Co., Ltd Copyright 2018 Red Hat Inc. Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice (including the next paragraph) shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. This description provides a high-level overview of the interplay between the interfaces defined this protocol. For details, see the protocol specification. The xx_session_manager protocol declares interfaces necessary to allow clients to restore toplevel state from previous executions. The xx_session_manager_v1.get_session request can be used to obtain a xx_session_v1 resource representing the state of a set of toplevels. Clients may obtain the session string to use in future calls through the xx_session_v1.created event. Compositors will use this string as an identifiable token for future runs, possibly storing data about the related toplevels in persistent storage. Toplevels are managed through the xx_session_v1.add_toplevel and xx_session_toplevel_v1.remove pair of requests. Clients will explicitly request a toplevel to be restored according to prior state through the xx_session_v1.restore_toplevel request before the toplevel is mapped. Warning! The protocol described in this file is currently in the experimental phase. Backwards incompatible major versions of the protocol are to be expected. Exposing this protocol without an opt-in mechanism is discouraged. The xx_session_manager interface defines base requests for creating and managing a session for an application. Sessions persist across application and compositor restarts unless explicitly destroyed. A session is created for the purpose of maintaining an application's xdg_toplevel surfaces across compositor or application restarts. The compositor should remember as many states as possible for surfaces in a given session, but there is no requirement for which states must be remembered. The reason may determine in what way a session restores the window management state of associated toplevels. For example newly launched applications might be launched on the active workspace with restored size and position, while a recovered applications might restore additional state such as active workspace and stacking order. A new app instance is launched, for example from an app launcher. A app instance is recovering from for example a compositor or app crash. A app instance is restored, for example part of a restored session, or restored from having been temporarily terminated due to resource constraints. This has no effect other than to destroy the xx_session_manager object. Create a session object corresponding to either an existing session identified by the given session identifier string or a new session. While the session object exists, the session is considered to be "in use". If a identifier string represents a session that is currently actively in use by the the same client, an 'in_use' error is raised. If some other client is currently using the same session, the new session will replace managing the associated state. NULL is passed to initiate a new session. If an id is passed which does not represent a valid session, the compositor treats it as if NULL had been passed. A client is allowed to have any number of in use sessions at the same time. A xx_session_v1 object represents a session for an application. While the object exists, all surfaces which have been added to the session will have states stored by the compositor which can be reapplied at a later time. Two sessions cannot exist for the same identifier string. States for surfaces added to a session are automatically updated by the compositor when they are changed. Surfaces which have been added to a session are automatically removed from the session if xdg_toplevel.destroy is called for the surface. Destroy a session object, preserving the current state but not continuing to make further updates if state changes occur. This makes the associated xx_toplevel_session_v1 objects inert. Remove the session, making it no longer available for restoration. A compositor should in response to this request remove the data related to this session from its storage. Attempt to add a given surface to the session. The passed name is used to identify what window is being restored, and may be used store window specific state within the session. Calling this with a toplevel that is already managed by the session with the same associated will raise an in_use error. Inform the compositor that the toplevel associated with the passed name should have its window management state restored. Calling this with a toplevel that is already managed by the session with the same associated will raise an in_use error. This request must be called prior to the first commit on the associated wl_surface, otherwise an already_mapped error is raised. As part of the initial configure sequence, if the toplevel was successfully restored, a xx_toplevel_session_v1.restored event is emitted. See the xx_toplevel_session_v1.restored event for further details. Emitted at most once some time after getting a new session object. It means that no previous state was restored, and a new session was created. The passed id can be used to restore previous sessions. Emitted at most once some time after getting a new session object. It means that previous state was at least partially restored. The same id can again be used to restore previous sessions. Emitted at most once, if the session was taken over by some other client. When this happens, the session and all its toplevel session objects become inert, and should be destroyed. Destroy the object. This has no effect window management of the associated toplevel. Remove a specified surface from the session and render any corresponding xx_toplevel_session_v1 object inert. The compositor should remove any data related to the toplevel in the corresponding session from its internal storage. The "restored" event is emitted prior to the first xdg_toplevel.configure for the toplevel. It will only be emitted after xx_session_v1.restore_toplevel, and the initial empty surface state has been applied, and it indicates that the surface's session is being restored with this configure event.