Implement everything

.gitignore

@@ -0,0 +1,6 @@
+*.o
+wlr-output-power-management-unstable-v1.c
+wlr-output-power-management-unstable-v1.h
+xdg-output-unstable-v1.c
+xdg-output-unstable-v1.h
+wlopm

Makefile

@@ -0,0 +1,35 @@
+SCANNER := wayland-scanner
+
+PREFIX=/usr/local
+BINDIR=$(PREFIX)/bin
+MANDIR=$(PREFIX)/share/man
+
+CFLAGS=-Wall -Werror -Wextra -Wpedantic -Wno-unused-parameter -Wconversion
+LIBS=-lwayland-client
+OBJ=wlopm.o wlr-output-power-management-unstable-v1.o xdg-output-unstable-v1.o
+GEN=wlr-output-power-management-unstable-v1.c wlr-output-power-management-unstable-v1.h xdg-output-unstable-v1.c xdg-output-unstable-v1.h
+
+wlopm: $(OBJ)
+	$(CC)$ $(LDFLAGS) -o $@ $(OBJ) $(LIBS)
+
+$(OBJ): $(GEN)
+
+%.c: %.xml
+	$(SCANNER) private-code < $< > $@
+
+%.h: %.xml
+	$(SCANNER) client-header < $< > $@
+
+install: wlopm
+	install -D wlopm   $(DESTDIR)$(BINDIR)/wlopm
+	install -D wlopm.1 $(DESTDIR)$(MANDIR)/man1/wlopm.1
+
+uninstall:
+	$(RM) $(DESTDIR)$(BINDIR)/wlopm
+	$(RM) $(DESTDIR)$(MANDIR)/man1/wlopm.1
+
+clean:
+	$(RM) wlopm $(GEN) $(OBJ)
+
+.PHONY: clean install
+

wlopm.1

@@ -0,0 +1,31 @@
+.TH wlopm 1 2021-03-14 wlopm-0.0.1
+
+.SH NAME
+wlopm - Wayland output power management
+
+.SH DESCRIPTION
+wlopm is a simple client implementing zwlr-output-power-management-v1. It can be
+used to query and set the output power mode of Wayland outputs.
+
+.SH USAGE
+\fBwlopm\fR
+.RS 4
+List outputs and their power modes.
+.P
+.RE
+
+\fBwlopm on <output-name>\fR
+.RS 4
+Set output power mode to on.
+.P
+.RE
+
+\fBwlopm off <output-name>\fR
+.RS 4
+Set output power mode to off.
+.P
+.RE
+
+.SH AUTHOR
+Leon Henrik Plickat
+

wlopm.c

@@ -0,0 +1,307 @@
+/*
+ * wlopm - Wayland output power manager
+ *
+ * Copyright (C) 2021 Leon Henrik Plickat
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+
+#include <wayland-client.h>
+
+#include "xdg-output-unstable-v1.h"
+#include "wlr-output-power-management-unstable-v1.h"
+
+#define VERSION "0.0.1"
+
+const char usage[] =
+	"Usage:\n"
+	"\twlopm                     List outputs and their power modes.\n"
+	"\twlopm on  <output-name>   Set output power mode to on.\n"
+	"\twlopm off <output-name>   Set output power mode to off.\n"
+	"\n";
+
+enum Action
+{
+	LIST,
+	ON,
+	OFF,
+};
+
+enum Action action = LIST;
+char *name = NULL;
+
+struct Output
+{
+	struct wl_list link;
+	struct wl_output *wl_output;
+	struct zxdg_output_v1 *xdg_output;
+	struct zwlr_output_power_v1 *wlr_output_power;
+	enum zwlr_output_power_v1_mode mode;
+	char *name;
+	uint32_t global_name;
+};
+
+struct wl_display *wl_display = NULL;
+struct wl_registry *wl_registry = NULL;
+struct wl_callback *sync_callback = NULL;
+
+struct wl_list outputs;
+
+struct zxdg_output_manager_v1 *xdg_output_manager = NULL;
+struct zwlr_output_power_manager_v1 *wlr_output_power_manager = NULL;
+
+int ret = EXIT_SUCCESS;
+bool loop = true;
+
+static void noop () {}
+
+static void wlr_output_power_handle_mode (void *data, struct zwlr_output_power_v1 *wlr_output_power,
+		enum zwlr_output_power_v1_mode mode)
+{
+	struct Output *output = (struct Output *)data;
+	output->mode = mode;
+}
+
+static void wlr_output_power_handle_failed (void *data, struct zwlr_output_power_v1 *wlr_output_power)
+{
+	struct Output *output = (struct Output *)data;
+	fprintf(stderr, "ERROR: Setting mode for output \"%s\" failed.\n", output->name);
+	loop = false;
+	ret = EXIT_FAILURE;
+}
+
+static const struct zwlr_output_power_v1_listener wlr_output_power_listener = {
+	.mode   = wlr_output_power_handle_mode,
+	.failed = wlr_output_power_handle_failed,
+};
+
+static void xdg_output_handle_name (void *data, struct zxdg_output_v1 *xdg_output,
+		const char *name)
+{
+	struct Output *output = (struct Output *)data;
+	if ( output->name != NULL )
+		free(output->name);
+	output->name = strdup(name);
+}
+
+static const struct zxdg_output_v1_listener xdg_output_listener = {
+	.logical_size     = noop,
+	.name             = xdg_output_handle_name,
+	.logical_position = noop,
+	.description      = noop,
+	.done             = noop, /* Deprecated since version 3. */
+};
+
+static void registry_handle_global (void *data, struct wl_registry *registry,
+		uint32_t name, const char *interface, uint32_t version)
+{
+	if ( strcmp(interface, wl_output_interface.name) == 0 )
+	{
+		struct Output *output = calloc(1, sizeof(struct Output));
+		if ( output == NULL )
+		{
+			fputs("ERROR: Failed to allocate.\n", stderr);
+			return;
+		}
+
+		output->wl_output = wl_registry_bind(registry, name, 
+				&wl_output_interface, version);
+		output->xdg_output = NULL;
+		output->name = NULL;
+		output->global_name = name;
+
+		wl_list_insert(&outputs, &output->link);
+	}
+	else if ( strcmp(interface, zxdg_output_manager_v1_interface.name) == 0 )
+		xdg_output_manager = wl_registry_bind(registry, name,
+				&zxdg_output_manager_v1_interface, version);
+	else if ( strcmp(interface, zwlr_output_power_manager_v1_interface.name) == 0 )
+		wlr_output_power_manager = wl_registry_bind(registry, name,
+				&zwlr_output_power_manager_v1_interface, version);
+}
+
+static const struct wl_registry_listener registry_listener = {
+	.global        = registry_handle_global,
+	.global_remove = noop, /* We don't run long enough to care. */
+};
+
+static void sync_handle_done (void *data, struct wl_callback *wl_callback, uint32_t other_data);
+static const struct wl_callback_listener sync_callback_listener = {
+	.done = sync_handle_done,
+};
+
+static void sync_handle_done (void *data, struct wl_callback *wl_callback, uint32_t other_data)
+{
+	wl_callback_destroy(wl_callback);
+	sync_callback = NULL;
+
+	static int sync = 0;
+	if ( sync == 0 )
+	{
+		if ( wlr_output_power_manager == NULL )
+		{
+			fputs("ERROR: Wayland server does not support wlr-output-power-management-v1.\n", stderr);
+			loop = false;
+			ret = EXIT_FAILURE;
+			return;
+		}
+
+		if ( xdg_output_manager == NULL )
+		{
+			fputs("ERROR: Wayland server does not support xdg-output.\n", stderr);
+			loop = false;
+			ret = EXIT_FAILURE;
+			return;
+		}
+
+		struct Output *output;
+		wl_list_for_each(output, &outputs, link)
+		{
+			output->xdg_output = zxdg_output_manager_v1_get_xdg_output(
+					xdg_output_manager, output->wl_output);
+			zxdg_output_v1_add_listener(output->xdg_output,
+					&xdg_output_listener, output);
+
+			output->wlr_output_power = zwlr_output_power_manager_v1_get_output_power(
+					wlr_output_power_manager, output->wl_output);
+			zwlr_output_power_v1_add_listener(output->wlr_output_power,
+					&wlr_output_power_listener, output);
+		}
+
+		sync_callback = wl_display_sync(wl_display);
+		wl_callback_add_listener(sync_callback, &sync_callback_listener, NULL);
+	}
+	else if ( sync == 1 )
+	{
+		if ( action == LIST )
+		{
+			struct Output *output;
+			wl_list_for_each(output, &outputs, link)
+				fprintf(stdout, "%s %s\n", output->name,
+						output->mode == ZWLR_OUTPUT_POWER_V1_MODE_ON ? "on" : "off");
+			loop = false;
+		}
+		else
+		{
+			struct Output *output;
+			wl_list_for_each(output, &outputs, link)
+				if ( strcmp(output->name, name) == 0 )
+					goto found;
+			fprintf(stdout, "ERROR: No output with name \"%s\".\n", name);
+			ret = EXIT_FAILURE;
+			loop = false;
+			return;
+found:
+			zwlr_output_power_v1_set_mode(output->wlr_output_power,
+					action == ON ? ZWLR_OUTPUT_POWER_V1_MODE_ON : ZWLR_OUTPUT_POWER_V1_MODE_OFF);
+
+			/* We need to sync yet another time because setting the
+			 * power mode might fail.
+			 */
+			sync_callback = wl_display_sync(wl_display);
+			wl_callback_add_listener(sync_callback, &sync_callback_listener, NULL);
+		}
+	}
+	else
+		loop = false;
+	sync++;
+}
+
+int main(int argc, char *argv[])
+{
+	if ( argc == 3 )
+	{
+		if ( strcmp(argv[1], "on") == 0 )
+			action = ON;
+		else if ( strcmp(argv[1], "off") == 0 )
+			action = OFF;
+		else
+		{
+			fputs(usage, stderr);
+			return EXIT_FAILURE;
+		}
+
+		name = strdup(argv[2]);
+	}
+	else if ( argc != 1 )
+	{
+		fputs(usage, stderr);
+		return EXIT_FAILURE;
+	}
+
+	/* We query the display name here instead of letting wl_display_connect()
+	 * figure it out itself, because libwayland (for legacy reasons) falls
+	 * back to using "wayland-0" when $WAYLAND_DISPLAY is not set, which is
+	 * generally not desirable.
+	 */
+	const char *display_name = getenv("WAYLAND_DISPLAY");
+	if ( display_name == NULL )
+	{
+		fputs("ERROR: WAYLAND_DISPLAY is not set.\n", stderr);
+		if ( name != NULL )
+			free(name);
+		return EXIT_FAILURE;
+	}
+
+	wl_display = wl_display_connect(display_name);
+	if ( wl_display == NULL )
+	{
+		fputs("ERROR: Can not connect to wayland display.\n", stderr);
+		if ( name != NULL )
+			free(name);
+		return EXIT_FAILURE;
+	}
+
+	wl_list_init(&outputs);
+
+	wl_registry = wl_display_get_registry(wl_display);
+	wl_registry_add_listener(wl_registry, &registry_listener, NULL);
+
+	sync_callback = wl_display_sync(wl_display);
+	wl_callback_add_listener(sync_callback, &sync_callback_listener, NULL);
+
+	while ( loop && wl_display_dispatch(wl_display) > 0 );
+
+	struct Output *output, *tmp;
+	wl_list_for_each_safe(output, tmp, &outputs, link)
+	{
+		zwlr_output_power_v1_destroy(output->wlr_output_power);
+		zxdg_output_v1_destroy(output->xdg_output);
+		wl_output_destroy(output->wl_output);
+		wl_list_remove(&output->link);
+		free(output->name);
+		free(output);
+	}
+
+	if ( name != NULL )
+		free(name);
+	if ( sync_callback != NULL )
+		wl_callback_destroy(sync_callback);
+	if ( wlr_output_power_manager != NULL )
+		zwlr_output_power_manager_v1_destroy(wlr_output_power_manager);
+	if ( xdg_output_manager != NULL )
+		zxdg_output_manager_v1_destroy(xdg_output_manager);
+	if ( wl_registry != NULL )
+		wl_registry_destroy(wl_registry);
+	wl_display_disconnect(wl_display);
+
+	return ret;
+}
+

wlr-output-power-management-unstable-v1.xml

@@ -0,0 +1,128 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<protocol name="wlr_output_power_management_unstable_v1">
+  <copyright>
+    Copyright © 2019 Purism SPC
+
+    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.
+  </copyright>
+
+  <description summary="Control power management modes of outputs">
+    This protocol allows clients to control power management modes
+    of outputs that are currently part of the compositor space. The
+    intent is to allow special clients like desktop shells to power
+    down outputs when the system is idle.
+
+    To modify outputs not currently part of the compositor space see
+    wlr-output-management.
+
+    Warning! The protocol described in this file is experimental and
+    backward incompatible changes may be made. Backward compatible changes
+    may be added together with the corresponding interface version bump.
+    Backward incompatible changes are done by bumping the version number in
+    the protocol and interface names and resetting the interface version.
+    Once the protocol is to be declared stable, the 'z' prefix and the
+    version number in the protocol and interface names are removed and the
+    interface version number is reset.
+  </description>
+
+  <interface name="zwlr_output_power_manager_v1" version="1">
+    <description summary="manager to create per-output power management">
+      This interface is a manager that allows creating per-output power
+      management mode controls.
+    </description>
+
+    <request name="get_output_power">
+      <description summary="get a power management for an output">
+        Create a output power management mode control that can be used to
+        adjust the power management mode for a given output.
+      </description>
+      <arg name="id" type="new_id" interface="zwlr_output_power_v1"/>
+      <arg name="output" type="object" interface="wl_output"/>
+    </request>
+
+    <request name="destroy" type="destructor">
+      <description summary="destroy the manager">
+        All objects created by the manager will still remain valid, until their
+        appropriate destroy request has been called.
+      </description>
+    </request>
+  </interface>
+
+  <interface name="zwlr_output_power_v1" version="1">
+    <description summary="adjust power management mode for an output">
+      This object offers requests to set the power management mode of
+      an output.
+    </description>
+
+    <enum name="mode">
+      <entry name="off" value="0"
+             summary="Output is turned off."/>
+      <entry name="on" value="1"
+             summary="Output is turned on, no power saving"/>
+    </enum>
+
+    <enum name="error">
+      <entry name="invalid_mode" value="1" summary="inexistent power save mode"/>
+    </enum>
+
+    <request name="set_mode">
+      <description summary="Set an outputs power save mode">
+        Set an output's power save mode to the given mode. The mode change
+        is effective immediately. If the output does not support the given
+        mode a failed event is sent.
+      </description>
+      <arg name="mode" type="uint" enum="mode" summary="the power save mode to set"/>
+    </request>
+
+    <event name="mode">
+      <description summary="Report a power management mode change">
+        Report the power management mode change of an output.
+
+        The mode event is sent after an output changed its power
+        management mode. The reason can be a client using set_mode or the
+        compositor deciding to change an output's mode.
+        This event is also sent immediately when the object is created
+        so the client is informed about the current power management mode.
+      </description>
+      <arg name="mode" type="uint" enum="mode"
+           summary="the output's new power management mode"/>
+    </event>
+
+    <event name="failed">
+      <description summary="object no longer valid">
+        This event indicates that the output power management mode control
+        is no longer valid. This can happen for a number of reasons,
+        including:
+        - The output doesn't support power management
+        - Another client already has exclusive power management mode control
+          for this output
+        - The output disappeared
+
+        Upon receiving this event, the client should destroy this object.
+      </description>
+    </event>
+
+    <request name="destroy" type="destructor">
+      <description summary="destroy this power management">
+        Destroys the output power management mode control object.
+      </description>
+    </request>
+  </interface>
+</protocol>

xdg-output-unstable-v1.xml

@@ -0,0 +1,220 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<protocol name="xdg_output_unstable_v1">
+
+  <copyright>
+    Copyright © 2017 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.
+  </copyright>
+
+  <description summary="Protocol to describe output regions">
+    This protocol aims at describing outputs in a way which is more in line
+    with the concept of an output on desktop oriented systems.
+
+    Some information are more specific to the concept of an output for
+    a desktop oriented system and may not make sense in other applications,
+    such as IVI systems for example.
+
+    Typically, the global compositor space on a desktop system is made of
+    a contiguous or overlapping set of rectangular regions.
+
+    Some of the information provided in this protocol might be identical
+    to their counterparts already available from wl_output, in which case
+    the information provided by this protocol should be preferred to their
+    equivalent in wl_output. The goal is to move the desktop specific
+    concepts (such as output location within the global compositor space,
+    the connector name and types, etc.) out of the core wl_output protocol.
+
+    Warning! The protocol described in this file is experimental and
+    backward incompatible changes may be made. Backward compatible
+    changes may be added together with the corresponding interface
+    version bump.
+    Backward incompatible changes are done by bumping the version
+    number in the protocol and interface names and resetting the
+    interface version. Once the protocol is to be declared stable,
+    the 'z' prefix and the version number in the protocol and
+    interface names are removed and the interface version number is
+    reset.
+  </description>
+
+  <interface name="zxdg_output_manager_v1" version="3">
+    <description summary="manage xdg_output objects">
+      A global factory interface for xdg_output objects.
+    </description>
+
+    <request name="destroy" type="destructor">
+      <description summary="destroy the xdg_output_manager object">
+	Using this request a client can tell the server that it is not
+	going to use the xdg_output_manager object anymore.
+
+	Any objects already created through this instance are not affected.
+      </description>
+    </request>
+
+    <request name="get_xdg_output">
+      <description summary="create an xdg output from a wl_output">
+	This creates a new xdg_output object for the given wl_output.
+      </description>
+      <arg name="id" type="new_id" interface="zxdg_output_v1"/>
+      <arg name="output" type="object" interface="wl_output"/>
+    </request>
+  </interface>
+
+  <interface name="zxdg_output_v1" version="3">
+    <description summary="compositor logical output region">
+      An xdg_output describes part of the compositor geometry.
+
+      This typically corresponds to a monitor that displays part of the
+      compositor space.
+
+      For objects version 3 onwards, after all xdg_output properties have been
+      sent (when the object is created and when properties are updated), a
+      wl_output.done event is sent. This allows changes to the output
+      properties to be seen as atomic, even if they happen via multiple events.
+    </description>
+
+    <request name="destroy" type="destructor">
+      <description summary="destroy the xdg_output object">
+	Using this request a client can tell the server that it is not
+	going to use the xdg_output object anymore.
+      </description>
+    </request>
+
+    <event name="logical_position">
+      <description summary="position of the output within the global compositor space">
+	The position event describes the location of the wl_output within
+	the global compositor space.
+
+	The logical_position event is sent after creating an xdg_output
+	(see xdg_output_manager.get_xdg_output) and whenever the location
+	of the output changes within the global compositor space.
+      </description>
+      <arg name="x" type="int"
+	   summary="x position within the global compositor space"/>
+      <arg name="y" type="int"
+	   summary="y position within the global compositor space"/>
+    </event>
+
+    <event name="logical_size">
+      <description summary="size of the output in the global compositor space">
+	The logical_size event describes the size of the output in the
+	global compositor space.
+
+	For example, a surface without any buffer scale, transformation
+	nor rotation set, with the size matching the logical_size will
+	have the same size as the corresponding output when displayed.
+
+	Most regular Wayland clients should not pay attention to the
+	logical size and would rather rely on xdg_shell interfaces.
+
+	Some clients such as Xwayland, however, need this to configure
+	their surfaces in the global compositor space as the compositor
+	may apply a different scale from what is advertised by the output
+	scaling property (to achieve fractional scaling, for example).
+
+	For example, for a wl_output mode 3840×2160 and a scale factor 2:
+
+	- A compositor not scaling the surface buffers will advertise a
+	  logical size of 3840×2160,
+
+	- A compositor automatically scaling the surface buffers will
+	  advertise a logical size of 1920×1080,
+
+	- A compositor using a fractional scale of 1.5 will advertise a
+	  logical size to 2560×1620.
+
+	For example, for a wl_output mode 1920×1080 and a 90 degree rotation,
+	the compositor will advertise a logical size of 1080x1920.
+
+	The logical_size event is sent after creating an xdg_output
+	(see xdg_output_manager.get_xdg_output) and whenever the logical
+	size of the output changes, either as a result of a change in the
+	applied scale or because of a change in the corresponding output
+	mode(see wl_output.mode) or transform (see wl_output.transform).
+      </description>
+      <arg name="width" type="int"
+	   summary="width in global compositor space"/>
+      <arg name="height" type="int"
+	   summary="height in global compositor space"/>
+    </event>
+
+    <event name="done">
+      <description summary="all information about the output have been sent">
+	This event is sent after all other properties of an xdg_output
+	have been sent.
+
+	This allows changes to the xdg_output properties to be seen as
+	atomic, even if they happen via multiple events.
+
+	For objects version 3 onwards, this event is deprecated. Compositors
+	are not required to send it anymore and must send wl_output.done
+	instead.
+      </description>
+    </event>
+
+    <!-- Version 2 additions -->
+
+    <event name="name" since="2">
+      <description summary="name of this output">
+	Many compositors will assign names to their outputs, show them to the
+	user, allow them to be configured by name, etc. The client may wish to
+	know this name as well to offer the user similar behaviors.
+
+	The naming convention is compositor defined, but limited to
+	alphanumeric characters and dashes (-). Each name is unique among all
+	wl_output globals, but if a wl_output global is destroyed the same name
+	may be reused later. The names will also remain consistent across
+	sessions with the same hardware and software configuration.
+
+	Examples of names include 'HDMI-A-1', 'WL-1', 'X11-1', etc. However, do
+	not assume that the name is a reflection of an underlying DRM
+	connector, X11 connection, etc.
+
+	The name event is sent after creating an xdg_output (see
+	xdg_output_manager.get_xdg_output). This event is only sent once per
+	xdg_output, and the name does not change over the lifetime of the
+	wl_output global.
+      </description>
+      <arg name="name" type="string" summary="output name"/>
+    </event>
+
+    <event name="description" since="2">
+      <description summary="human-readable description of this output">
+	Many compositors can produce human-readable descriptions of their
+	outputs.  The client may wish to know this description as well, to
+	communicate the user for various purposes.
+
+	The description is a UTF-8 string with no convention defined for its
+	contents. Examples might include 'Foocorp 11" Display' or 'Virtual X11
+	output via :1'.
+
+	The description event is sent after creating an xdg_output (see
+	xdg_output_manager.get_xdg_output) and whenever the description
+	changes. The description is optional, and may not be sent at all.
+
+	For objects of version 2 and lower, this event is only sent once per
+	xdg_output, and the description does not change over the lifetime of
+	the wl_output global.
+      </description>
+      <arg name="description" type="string" summary="output description"/>
+    </event>
+
+  </interface>
+</protocol>