Implement Tray Icons

This commit implements the StatusNotifierItem protocol, and enables
swaybar to show tray icons. It also uses `xembedsniproxy` in order to
communicate with xembed applications.
The tray is completely optional, and can be disabled on compile time
with the `enable-tray` option. Or on runtime with the bar config option
`tray_output none`.

Overview of changes:
In swaybar very little is changed outside the tray subfolder except
that all events are now polled in `event_loop.c`, this creates no
functional difference.

Six bar configuration options were added, these are detailed in
sway-bar(5)

The tray subfolder is where all protocol implementation takes place and
is organised as follows:

tray/sni_watcher.c:
	This file contains the StatusNotifierWatcher. It keeps track of
	items and hosts and reports when they come or go.
tray/tray.c
	This file contains the StatusNotifierHost. It keeps track of
	sway's version of the items and represents the tray itself.
tray/sni.c
	This file contains the StatusNotifierItem struct and all
	communication with individual items.
tray/icon.c
	This file implements the icon theme protocol. It allows for
	finding icons by name, rather than by pixmap.
tray/dbus.c
	This file allows for asynchronous DBus communication.

See #986 #343

1 files changed, 24 insertions, 2 deletions

diff --git a/sway/commands/bar/tray_output.c b/sway/commands/bar/tray_output.c
index 8a1b5d35..012304a9 100644
--- a/sway/commands/bar/tray_output.c
+++ b/sway/commands/bar/tray_output.c
@@ -1,7 +1,29 @@
+#define _XOPEN_SOURCE 500
+#include <string.h>
 #include "sway/commands.h"
-#include "log.h"
 
 struct cmd_results *bar_cmd_tray_output(int argc, char **argv) {
-        sway_log(L_ERROR, "Warning: tray_output is not supported on wayland");
+        const char *cmd_name = "tray_output";
+#ifndef ENABLE_TRAY
+        return cmd_results_new(CMD_INVALID, cmd_name, "Invalid %s command "
+                        "%s called, but sway was compiled without tray support",
+                        cmd_name, cmd_name);
+#else
+        struct cmd_results *error = NULL;
+        if ((error = checkarg(argc, cmd_name, EXPECTED_EQUAL_TO, 1))) {
+                return error;
+        }
+
+        if (!config->current_bar) {
+                return cmd_results_new(CMD_FAILURE, cmd_name, "No bar defined.");
+        }
+
+        if (strcmp(argv[0], "all") == 0) {
+                // Default behaviour
+                return cmd_results_new(CMD_SUCCESS, NULL, NULL);
+        }
+        config->current_bar->tray_output = strdup(argv[0]);
+
         return cmd_results_new(CMD_SUCCESS, NULL, NULL);
+#endif
 }