This allows us to have a device support multiple interfaces and evolve
those interfaces individually, e.g. add things to the keyboard interface
without having to bump the touchscreen interface.
Note that due to a name clash with the existing struct ei_touch public
API the protocol interface is named touchscreen.
The idea here is that the client announces the interfaces it can support
and their version (including the core ei_connection). The server can
then send the various bits based on those versions, where applicable.
This replaces the connect/connect_done and version/get_version requests.
Immediately after connecting, the server sends an ei_protocol_setup
event to the client with the ID of the object and the server's highest
supported version number (of this object).
This is a one-shot object that the client can use to configure its name
and whether it is a sender or receiver context. Once .done is sent, the
object is discarded.
The server version is sent along to the client to allow for requests to
be added to this object in the future.
As a fixme left: the client now assumes to be connected as soon as the
.done request is sent and the following sync event is received. The
EIS implementation will not have actually eis_client_connect()ed the
client yet, but it's good enough for now.
Arguably, the CONNECTED event is superfluous anyway since *any* event
other than DISCONNECTED indicates connected status. CONNECTED is a
leftover from when the client created devices and needed to know if it's
worth doing so.
In the protocol this is a simple rename but in the implementation we can
now separate the protocol object out from the ei/ei-client context
itself by having the ei_connection objects.
This protocol is wayland-like though it uses a slightly different
message format. The XML file uses the same structure, except for the
"fixed" type which is "float" here.
The scanner uses a jinja template to generate source and header files
for ei and eis which are now used instead of the protobuf-generated
objects. Note that the scanner is a minimal working version, some
features like enum value checks are not yet implemented.
Unlike wayland we do not need to generate the libwayland-like library,
we only need the wire protocol parser - some shortcuts can thus be taken.
To keep the changes simple, the protocol currently is a flat protocol
with only one interface and all messages copied over from the previous
ei.proto file. In future commits, this will be moved to the respective
interfaces instead.
