On Wed, 1 May 2019 03:24:04 +0100 adlo <adloco...@gmail.com> wrote: > > On 29 Oct 2018, at 09:33, Pekka Paalanen <ppaala...@gmail.com> wrote: > > > > the only opinionated advice I can give you is don't do it. Instead, put > > the GTK stuff in a separate process, let your compositor fork & exec > > it, and talk to it through your own private protocol extension for the > > special bits you need. > > What are the basics for creating a private protocol extension, i.e. what's > the minimum boilerplate code needed? What's a simple example of how to > implement a request between the two processes? The Weston source code is > difficult to follow. > > How do I allow the child process to call functions and pass data to the > parent and vice versa?
Hi adlo, it is all just the normal Wayland protocol exchange but with a new interface of your own design. I'm not sure if there is a really minimal example, but I'll list at least some. One example of such private protocol extension is https://gitlab.freedesktop.org/wayland/weston/blob/master/protocol/weston-desktop-shell.xml The server-side implementation of it is in shell.c and the entrypoint to that is https://gitlab.freedesktop.org/wayland/weston/blob/master/desktop-shell/shell.c#L5143 wl_global_create(ec->wl_display, &weston_desktop_shell_interface, 1, shell, bind_desktop_shell) which installs the protocol extension in the compositor. You can see everything about the implementation by following all callbacks that get registered, starting with bind_desktop_shell(). The privacy of the protocol extension, the installed wayland global really, is achieved in https://gitlab.freedesktop.org/wayland/weston/blob/master/desktop-shell/shell.c#L4366 shell->child.client = weston_client_start(shell->compositor, shell->client); which creates the Wayland connection before forking the child process and bind_desktop_shell() then verifying the client trying to bind to the global is the client that was forked. The client-side implementation is in desktop-shell.c with the entry point at https://gitlab.freedesktop.org/wayland/weston/blob/master/clients/desktop-shell.c#L1392 if (!strcmp(interface, "weston_desktop_shell")) { desktop->shell = display_bind(desktop->display, id, &weston_desktop_shell_interface, 1); weston_desktop_shell_add_listener(desktop->shell, &listener, desktop); https://gitlab.freedesktop.org/wayland/weston/blob/master/protocol/weston-touch-calibration.xml is another example of a custom protocol extension (not for a shell helper client though), with implementations in https://gitlab.freedesktop.org/wayland/weston/blob/master/libweston/touch-calibration.c and https://gitlab.freedesktop.org/wayland/weston/blob/master/clients/touch-calibrator.c Again, you can find the entry points with wl_global_create() and display_bind(), respectively. There is also https://gitlab.freedesktop.org/wayland/weston/blob/master/protocol/weston-test.xml used by the test suite exclusively, implemented in https://gitlab.freedesktop.org/wayland/weston/blob/master/tests/weston-test.c and https://gitlab.freedesktop.org/wayland/weston/blob/master/tests/weston-test-client-helper.c this time using wl_global_create() and wl_registry_bind(). Yet another external example is https://github.com/raspberrypi/maynard/ which contains its own additional protocol extensions and both a weston plugin and a GTK-based helper client. Unfortunately it hasn't been touched in a few years, so it probably won't work with a recent Weston. Hope this helps. Thanks, pq
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