~kennylevinsen/wayllpaper

e93449e9da85ae6948660d7ecdea92bddc02f421 — Kenny Levinsen 1 year, 1 month ago
Initial commit
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root = true

[*]
end_of_line = lf
insert_final_newline = true
trim_trailing_whitespace = true
indent_style = tab
indent_size = 8

A  => .gitignore +2 -0
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build/
.cache/

A  => LICENSE +7 -0
@@ 1,7 @@
Copyright 2023 Kenny Levinsen

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 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.

A  => README.md +47 -0
@@ 1,47 @@
# wayllpaper

Likely the fastest, least user-friendly, and worst named Wayland wallpaper utility possible. Requires for `zwlr_layer_shell_v1` and `wp_viewporter`.

The wallpaper is stored in ARGB8888 format on disk, so that a file descriptor for the file can be sent straight to the Wayland server. All outputs share the same buffer, and a viewport is used to match the content to each output.

Unscientific speed comparison with three 4k displays, measured from start of main to surface commit:

| tool       | input        | first output | last output |
|------------|--------------|--------------|-------------|
| wayllpaper | 31.6 MiB bin |         1 ms |        1 ms |
| wbg        |  0.6 MiB jpg |        74 ms |      122 ms |
| wbg        |  1.9 MiB png |       111 ms |      156 ms |
| wbg        |  2.3 MiB jpg |       193 ms |      240 ms |
| swaybg     |  0.6 MiB jpg |        76 ms |      119 ms |
| swaybg     |  1.9 MiB png |       123 ms |      161 ms |
| swaybg     |  2.3 MiB jpg |       177 ms |      215 ms |

# How to build and install

```
meson build
ninja -C build
sudo ninja -C build install
```

# How to use

First, convert the background to a raw ARGB8888 file. A tool to convert from PNG is included:

```shell
$ wayllpaper-convert input.png wallpaper.bin
width:  3840
height: 2160
```

Then run wayllpaper using the output from the above to show the wallpaper:

```shell
$ wayllpaper wallpaper.bin 3840 2160
```

The dimensions are required as the file does not contain any metadata, only raw pixel values.

# Help

Go to #kennylevinsen @ irc.libera.chat to discuss, or use [~kennylevinsen/public-inbox@lists.sr.ht](https://lists.sr.ht/~kennylevinsen/public-inbox)

A  => main.c +237 -0
@@ 1,237 @@
#define _DEFAULT_SOURCE
#define _XOPEN_SOURCE 700
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <poll.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>

#include <wayland-client-protocol.h>
#include <wayland-client.h>

#include "viewporter-client-protocol.h"
#include "wlr-layer-shell-unstable-v1-client-protocol.h"

struct context {
	struct wl_compositor *wl_compositor;
	struct zwlr_layer_shell_v1 *layer_shell;
	struct wp_viewporter *wp_viewporter;

	int fd;
	int width, height;
	struct wl_buffer *buffer;

	struct wl_list outputs;
};

struct output {
	struct wl_list link;

	struct context *context;
	struct wl_output *wl_output;
	uint32_t id;

	struct wl_surface *wl_surface;
	struct wp_viewport *wp_viewport;
	struct zwlr_layer_surface_v1 *layer_surface;
	uint32_t width, height;
};

static void layer_surface_configure(void *data, struct zwlr_layer_surface_v1 *surface,
				    uint32_t serial, uint32_t w, uint32_t h) {
	struct output *output = data;
	struct context *ctx = output->context;
	zwlr_layer_surface_v1_ack_configure(surface, serial);

	if (output->width != w || output->height != h) {
		output->width = w;
		output->height = h;
		wl_surface_attach(output->wl_surface, ctx->buffer, 0, 0);
		wp_viewport_set_destination(output->wp_viewport, output->width, output->height);
	}
	wl_surface_commit(output->wl_surface);
}

static void layer_surface_closed(void *data, struct zwlr_layer_surface_v1 *surface) {
	struct output *output = data;
	zwlr_layer_surface_v1_destroy(surface);
	wp_viewport_destroy(output->wp_viewport);
	wl_surface_destroy(output->wl_surface);
	output->layer_surface = NULL;
	output->wp_viewport = NULL;
	output->wl_surface = NULL;
}

struct zwlr_layer_surface_v1_listener layer_surface_listener = {
	.configure = layer_surface_configure,
	.closed = layer_surface_closed,
};

static void prepare_output(struct output *output) {
	struct context *ctx = output->context;
	if (ctx->wl_compositor == NULL || ctx->wp_viewporter == NULL || ctx->layer_shell == NULL ||
	    ctx->buffer == NULL) {
		return;
	}
	if (output->layer_surface != NULL) {
		return;
	}

	output->wl_surface = wl_compositor_create_surface(ctx->wl_compositor);
	output->wp_viewport = wp_viewporter_get_viewport(ctx->wp_viewporter, output->wl_surface);
	output->layer_surface =
		zwlr_layer_shell_v1_get_layer_surface(ctx->layer_shell, output->wl_surface,
						      output->wl_output,
						      ZWLR_LAYER_SHELL_V1_LAYER_BACKGROUND,
						      "wayllpaper");

	zwlr_layer_surface_v1_add_listener(output->layer_surface, &layer_surface_listener, output);

	zwlr_layer_surface_v1_set_anchor(output->layer_surface,
					 ZWLR_LAYER_SURFACE_V1_ANCHOR_TOP |
						 ZWLR_LAYER_SURFACE_V1_ANCHOR_BOTTOM |
						 ZWLR_LAYER_SURFACE_V1_ANCHOR_LEFT |
						 ZWLR_LAYER_SURFACE_V1_ANCHOR_RIGHT);
	wl_surface_commit(output->wl_surface);
}

static void finish_output(struct output *output) {
	zwlr_layer_surface_v1_destroy(output->layer_surface);
	wp_viewport_destroy(output->wp_viewport);
	wl_surface_destroy(output->wl_surface);
	output->layer_surface = NULL;
	output->wp_viewport = NULL;
	output->wl_surface = NULL;
}

static void registry_handle_global(void *data, struct wl_registry *registry, uint32_t name,
				   const char *interface, uint32_t version) {
	struct context *ctx = (struct context *)data;
	if (strcmp(interface, wl_output_interface.name) == 0) {
		fprintf(stderr, "registry: adding output %d\n", name);
		struct output *output = calloc(1, sizeof(struct output));
		output->id = name;
		output->wl_output = wl_registry_bind(registry, name, &wl_output_interface, 1);
		output->context = ctx;
		wl_list_insert(&ctx->outputs, &output->link);
	} else if (strcmp(interface, wl_compositor_interface.name) == 0) {
		ctx->wl_compositor = wl_registry_bind(registry, name, &wl_compositor_interface, 1);
	} else if (strcmp(interface, wp_viewporter_interface.name) == 0) {
		ctx->wp_viewporter = wl_registry_bind(registry, name, &wp_viewporter_interface, 1);
	} else if (strcmp(interface, wl_shm_interface.name) == 0) {
		struct wl_shm *shm = wl_registry_bind(registry, name, &wl_shm_interface, 1);
		struct wl_shm_pool *pool =
			wl_shm_create_pool(shm, ctx->fd, ctx->width * ctx->height * 4);
		ctx->buffer = wl_shm_pool_create_buffer(pool, 0, ctx->width, ctx->height,
							ctx->width * 4, WL_SHM_FORMAT_ARGB8888);
		wl_shm_pool_destroy(pool);

		close(ctx->fd);
		ctx->fd = -1;
	} else if (strcmp(interface, zwlr_layer_shell_v1_interface.name) == 0) {
		assert(version >= 3);
		ctx->layer_shell =
			wl_registry_bind(registry, name, &zwlr_layer_shell_v1_interface, 3);
	} else {
		return;
	}

	struct output *output;
	wl_list_for_each(output, &ctx->outputs, link) {
		prepare_output(output);
	}
}

static void registry_handle_global_remove(void *data, struct wl_registry *registry, uint32_t name) {
	(void)registry;
	struct context *ctx = (struct context *)data;
	struct output *output, *tmp;
	wl_list_for_each_safe(output, tmp, &ctx->outputs, link) {
		if (output->id == name) {
			fprintf(stderr, "registry: removing output %d\n", name);
			finish_output(output);
			wl_list_remove(&output->link);
			free(output);
			break;
		}
	}
}

static const struct wl_registry_listener registry_listener = {
	.global = registry_handle_global,
	.global_remove = registry_handle_global_remove,
};

static const char usage[] = "usage: wayllpaper filename width height\n";

int main(int argc, char *argv[]) {
	if (argc != 4) {
		fprintf(stderr, usage);
		return argc == 1 ? EXIT_SUCCESS : EXIT_FAILURE;
	}
	char *filename = argv[1];
	int width = atoi(argv[2]);
	int height = atoi(argv[3]);

	if (filename == NULL) {
		fprintf(stderr, "no file selected\n");
		return EXIT_FAILURE;
	}

	int fd = open(filename, O_RDWR | O_EXCL);
	if (fd == -1) {
		fprintf(stderr, "could not open file: %d\n", errno);
		return EXIT_FAILURE;
	}

	struct stat st;
	if (fstat(fd, &st) == -1) {
		fprintf(stderr, "could not stat file: %d\n", errno);
		return EXIT_FAILURE;
	}

	if (st.st_size != width * height * 4) {
		fprintf(stderr, "dimensions do not match file size: %ld != %d\n", st.st_size,
			width * height * 4);
		return EXIT_FAILURE;
	}

	// Initialize defaults
	struct context ctx = {
		.fd = fd,
		.width = width,
		.height = height,
	};
	wl_list_init(&ctx.outputs);

	struct wl_display *display = wl_display_connect(NULL);
	if (display == NULL) {
		fprintf(stderr, "could not create display\n");
		return EXIT_FAILURE;
	}

	struct wl_registry *registry = wl_display_get_registry(display);
	wl_registry_add_listener(registry, &registry_listener, &ctx);
	wl_display_roundtrip(display);

	struct output *output;
	wl_list_for_each(output, &ctx.outputs, link) {
		if (output->layer_surface == NULL) {
			fprintf(stderr,
				"could not prepare layer surfaces, possible missing interface\n");
			return EXIT_FAILURE;
		}
	}

	while (wl_display_dispatch(display) != -1) {
		// pass
	}

	return EXIT_SUCCESS;
}

A  => meson.build +73 -0
@@ 1,73 @@
project(
	'wayllpaper',
	'c',
	version: '0.1.0',
	license: 'MIT',
	meson_version: '>=0.58.0',
	default_options: [
		'c_std=c11',
		'warning_level=3',
		'werror=true',
	],
)

add_project_arguments(
	[
		'-Wundef',
		'-Wunused',
		'-Wlogical-op',
		'-Wmissing-include-dirs',
		'-Wold-style-definition', # nop
		'-Wpointer-arith',
		'-Wstrict-prototypes',
		'-Wmissing-prototypes',
		'-Wno-implicit-fallthrough',
		'-Wno-unknown-warning-option',
		'-Wno-unused-command-line-argument',
		'-Wvla',
		'-Wl,--exclude-libs=ALL',
		'-DWAYLL_VERSION="@0@"'.format(meson.project_version()),
	],
	language: 'c',
)

wl_client = dependency('wayland-client')
wl_protocols = dependency('wayland-protocols')
wl_protocols_dir = wl_protocols.get_variable('pkgdatadir')

scanner = find_program('wayland-scanner')
scanner_private_code = generator(scanner, output: '@BASENAME@-protocol.c', arguments: ['private-code', '@INPUT@', '@OUTPUT@'])
scanner_client_header = generator(scanner, output: '@BASENAME@-client-protocol.h', arguments: ['client-header', '@INPUT@', '@OUTPUT@'])

protocols_src = [
	scanner_private_code.process(wl_protocols_dir / 'stable/xdg-shell/xdg-shell.xml'),
	scanner_private_code.process(wl_protocols_dir / 'stable/viewporter/viewporter.xml'),
	scanner_private_code.process('wlr-layer-shell-unstable-v1.xml'),
]
protocols_headers = [
	scanner_client_header.process(wl_protocols_dir / 'stable/xdg-shell/xdg-shell.xml'),
	scanner_client_header.process(wl_protocols_dir / 'stable/viewporter/viewporter.xml'),
	scanner_client_header.process('wlr-layer-shell-unstable-v1.xml'),
]

lib_protocols = static_library('protocols', protocols_src + protocols_headers, dependencies: wl_client)
protocols_dep = declare_dependency(link_with: lib_protocols, sources: protocols_headers)

cc = meson.get_compiler('c')

executable(
	'wayllpaper',
	['main.c'],
	dependencies: [wl_client, protocols_dep],
	install: true,
)

executable(
	'wayllpaper-convert',
	['wayllpaper-convert.c'],
	dependencies: [
		dependency('cairo'),
	],
	install: true,
)


A  => wayllpaper-convert.c +60 -0
@@ 1,60 @@
#include <cairo.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

int main(int argc, char **argv) {
	if (argc != 3) {
		fprintf(stderr, "wayllpaper-convert input.png output.bin");
		return EXIT_FAILURE;
	}

	char *input = argv[1];
	char *output = argv[2];
	cairo_surface_t *image = cairo_image_surface_create_from_png(input);
	if (!image) {
		fprintf(stderr, "could not read image\n");
		return EXIT_FAILURE;
	}
	if (cairo_surface_status(image) != CAIRO_STATUS_SUCCESS) {
		fprintf(stderr, "could not read image: %s\n",
			cairo_status_to_string(cairo_surface_status(image)));
		return EXIT_FAILURE;
	}

	int width = cairo_image_surface_get_width(image);
	int height = cairo_image_surface_get_height(image);
	if (cairo_image_surface_get_format(image) != CAIRO_FORMAT_RGB24) {
		fprintf(stderr, "unexpected cairo format: %d\n",
			cairo_image_surface_get_format(image));
		return EXIT_FAILURE;
	}

	printf("width:  %d\n", width);
	printf("height: %d\n", height);

	int size = width * height * 4;

	int fd = creat(output, 0750);
	if (fd == -1) {
		fprintf(stderr, "unable to open output: %s\n", strerror(errno));
		return EXIT_FAILURE;
	}

	ssize_t total = 0;
	void *p = cairo_image_surface_get_data(image);

	while (total < size) {
		ssize_t n = write(fd, (char *)p + total, size - total);
		if (n < 0) {
			fprintf(stderr, "unable to write: %s\n", strerror(errno));
			return EXIT_FAILURE;
		}
		total += n;
	}
	close(fd);
	return EXIT_SUCCESS;
}

A  => wlr-layer-shell-unstable-v1.xml +390 -0
@@ 1,390 @@
<?xml version="1.0" encoding="UTF-8"?>
<protocol name="wlr_layer_shell_unstable_v1">
  <copyright>
    Copyright © 2017 Drew DeVault

    Permission to use, copy, modify, distribute, and sell this
    software and its documentation for any purpose is hereby granted
    without fee, provided that the above copyright notice appear in
    all copies and that both that copyright notice and this permission
    notice appear in supporting documentation, and that the name of
    the copyright holders not be used in advertising or publicity
    pertaining to distribution of the software without specific,
    written prior permission.  The copyright holders make no
    representations about the suitability of this software for any
    purpose.  It is provided "as is" without express or implied
    warranty.

    THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
    SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
    FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
    SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
    AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
    ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
    THIS SOFTWARE.
  </copyright>

  <interface name="zwlr_layer_shell_v1" version="4">
    <description summary="create surfaces that are layers of the desktop">
      Clients can use this interface to assign the surface_layer role to
      wl_surfaces. Such surfaces are assigned to a "layer" of the output and
      rendered with a defined z-depth respective to each other. They may also be
      anchored to the edges and corners of a screen and specify input handling
      semantics. This interface should be suitable for the implementation of
      many desktop shell components, and a broad number of other applications
      that interact with the desktop.
    </description>

    <request name="get_layer_surface">
      <description summary="create a layer_surface from a surface">
        Create a layer surface for an existing surface. This assigns the role of
        layer_surface, or raises a protocol error if another role is already
        assigned.

        Creating a layer surface from a wl_surface which has a buffer attached
        or committed is a client error, and any attempts by a client to attach
        or manipulate a buffer prior to the first layer_surface.configure call
        must also be treated as errors.

        After creating a layer_surface object and setting it up, the client
        must perform an initial commit without any buffer attached.
        The compositor will reply with a layer_surface.configure event.
        The client must acknowledge it and is then allowed to attach a buffer
        to map the surface.

        You may pass NULL for output to allow the compositor to decide which
        output to use. Generally this will be the one that the user most
        recently interacted with.

        Clients can specify a namespace that defines the purpose of the layer
        surface.
      </description>
      <arg name="id" type="new_id" interface="zwlr_layer_surface_v1"/>
      <arg name="surface" type="object" interface="wl_surface"/>
      <arg name="output" type="object" interface="wl_output" allow-null="true"/>
      <arg name="layer" type="uint" enum="layer" summary="layer to add this surface to"/>
      <arg name="namespace" type="string" summary="namespace for the layer surface"/>
    </request>

    <enum name="error">
      <entry name="role" value="0" summary="wl_surface has another role"/>
      <entry name="invalid_layer" value="1" summary="layer value is invalid"/>
      <entry name="already_constructed" value="2" summary="wl_surface has a buffer attached or committed"/>
    </enum>

    <enum name="layer">
      <description summary="available layers for surfaces">
        These values indicate which layers a surface can be rendered in. They
        are ordered by z depth, bottom-most first. Traditional shell surfaces
        will typically be rendered between the bottom and top layers.
        Fullscreen shell surfaces are typically rendered at the top layer.
        Multiple surfaces can share a single layer, and ordering within a
        single layer is undefined.
      </description>

      <entry name="background" value="0"/>
      <entry name="bottom" value="1"/>
      <entry name="top" value="2"/>
      <entry name="overlay" value="3"/>
    </enum>

    <!-- Version 3 additions -->

    <request name="destroy" type="destructor" since="3">
      <description summary="destroy the layer_shell object">
        This request indicates that the client will not use the layer_shell
        object any more. Objects that have been created through this instance
        are not affected.
      </description>
    </request>
  </interface>

  <interface name="zwlr_layer_surface_v1" version="4">
    <description summary="layer metadata interface">
      An interface that may be implemented by a wl_surface, for surfaces that
      are designed to be rendered as a layer of a stacked desktop-like
      environment.

      Layer surface state (layer, size, anchor, exclusive zone,
      margin, interactivity) is double-buffered, and will be applied at the
      time wl_surface.commit of the corresponding wl_surface is called.

      Attaching a null buffer to a layer surface unmaps it.

      Unmapping a layer_surface means that the surface cannot be shown by the
      compositor until it is explicitly mapped again. The layer_surface
      returns to the state it had right after layer_shell.get_layer_surface.
      The client can re-map the surface by performing a commit without any
      buffer attached, waiting for a configure event and handling it as usual.
    </description>

    <request name="set_size">
      <description summary="sets the size of the surface">
        Sets the size of the surface in surface-local coordinates. The
        compositor will display the surface centered with respect to its
        anchors.

        If you pass 0 for either value, the compositor will assign it and
        inform you of the assignment in the configure event. You must set your
        anchor to opposite edges in the dimensions you omit; not doing so is a
        protocol error. Both values are 0 by default.

        Size is double-buffered, see wl_surface.commit.
      </description>
      <arg name="width" type="uint"/>
      <arg name="height" type="uint"/>
    </request>

    <request name="set_anchor">
      <description summary="configures the anchor point of the surface">
        Requests that the compositor anchor the surface to the specified edges
        and corners. If two orthogonal edges are specified (e.g. 'top' and
        'left'), then the anchor point will be the intersection of the edges
        (e.g. the top left corner of the output); otherwise the anchor point
        will be centered on that edge, or in the center if none is specified.

        Anchor is double-buffered, see wl_surface.commit.
      </description>
      <arg name="anchor" type="uint" enum="anchor"/>
    </request>

    <request name="set_exclusive_zone">
      <description summary="configures the exclusive geometry of this surface">
        Requests that the compositor avoids occluding an area with other
        surfaces. The compositor's use of this information is
        implementation-dependent - do not assume that this region will not
        actually be occluded.

        A positive value is only meaningful if the surface is anchored to one
        edge or an edge and both perpendicular edges. If the surface is not
        anchored, anchored to only two perpendicular edges (a corner), anchored
        to only two parallel edges or anchored to all edges, a positive value
        will be treated the same as zero.

        A positive zone is the distance from the edge in surface-local
        coordinates to consider exclusive.

        Surfaces that do not wish to have an exclusive zone may instead specify
        how they should interact with surfaces that do. If set to zero, the
        surface indicates that it would like to be moved to avoid occluding
        surfaces with a positive exclusive zone. If set to -1, the surface
        indicates that it would not like to be moved to accommodate for other
        surfaces, and the compositor should extend it all the way to the edges
        it is anchored to.

        For example, a panel might set its exclusive zone to 10, so that
        maximized shell surfaces are not shown on top of it. A notification
        might set its exclusive zone to 0, so that it is moved to avoid
        occluding the panel, but shell surfaces are shown underneath it. A
        wallpaper or lock screen might set their exclusive zone to -1, so that
        they stretch below or over the panel.

        The default value is 0.

        Exclusive zone is double-buffered, see wl_surface.commit.
      </description>
      <arg name="zone" type="int"/>
    </request>

    <request name="set_margin">
      <description summary="sets a margin from the anchor point">
        Requests that the surface be placed some distance away from the anchor
        point on the output, in surface-local coordinates. Setting this value
        for edges you are not anchored to has no effect.

        The exclusive zone includes the margin.

        Margin is double-buffered, see wl_surface.commit.
      </description>
      <arg name="top" type="int"/>
      <arg name="right" type="int"/>
      <arg name="bottom" type="int"/>
      <arg name="left" type="int"/>
    </request>

    <enum name="keyboard_interactivity">
      <description summary="types of keyboard interaction possible for a layer shell surface">
        Types of keyboard interaction possible for layer shell surfaces. The
        rationale for this is twofold: (1) some applications are not interested
        in keyboard events and not allowing them to be focused can improve the
        desktop experience; (2) some applications will want to take exclusive
        keyboard focus.
      </description>

      <entry name="none" value="0">
        <description summary="no keyboard focus is possible">
          This value indicates that this surface is not interested in keyboard
          events and the compositor should never assign it the keyboard focus.

          This is the default value, set for newly created layer shell surfaces.

          This is useful for e.g. desktop widgets that display information or
          only have interaction with non-keyboard input devices.
        </description>
      </entry>
      <entry name="exclusive" value="1">
        <description summary="request exclusive keyboard focus">
          Request exclusive keyboard focus if this surface is above the shell surface layer.

          For the top and overlay layers, the seat will always give
          exclusive keyboard focus to the top-most layer which has keyboard
          interactivity set to exclusive. If this layer contains multiple
          surfaces with keyboard interactivity set to exclusive, the compositor
          determines the one receiving keyboard events in an implementation-
          defined manner. In this case, no guarantee is made when this surface
          will receive keyboard focus (if ever).

          For the bottom and background layers, the compositor is allowed to use
          normal focus semantics.

          This setting is mainly intended for applications that need to ensure
          they receive all keyboard events, such as a lock screen or a password
          prompt.
        </description>
      </entry>
      <entry name="on_demand" value="2" since="4">
        <description summary="request regular keyboard focus semantics">
          This requests the compositor to allow this surface to be focused and
          unfocused by the user in an implementation-defined manner. The user
          should be able to unfocus this surface even regardless of the layer
          it is on.

          Typically, the compositor will want to use its normal mechanism to
          manage keyboard focus between layer shell surfaces with this setting
          and regular toplevels on the desktop layer (e.g. click to focus).
          Nevertheless, it is possible for a compositor to require a special
          interaction to focus or unfocus layer shell surfaces (e.g. requiring
          a click even if focus follows the mouse normally, or providing a
          keybinding to switch focus between layers).

          This setting is mainly intended for desktop shell components (e.g.
          panels) that allow keyboard interaction. Using this option can allow
          implementing a desktop shell that can be fully usable without the
          mouse.
        </description>
      </entry>
    </enum>

    <request name="set_keyboard_interactivity">
      <description summary="requests keyboard events">
        Set how keyboard events are delivered to this surface. By default,
        layer shell surfaces do not receive keyboard events; this request can
        be used to change this.

        This setting is inherited by child surfaces set by the get_popup
        request.

        Layer surfaces receive pointer, touch, and tablet events normally. If
        you do not want to receive them, set the input region on your surface
        to an empty region.

        Keyboard interactivity is double-buffered, see wl_surface.commit.
      </description>
      <arg name="keyboard_interactivity" type="uint" enum="keyboard_interactivity"/>
    </request>

    <request name="get_popup">
      <description summary="assign this layer_surface as an xdg_popup parent">
        This assigns an xdg_popup's parent to this layer_surface.  This popup
        should have been created via xdg_surface::get_popup with the parent set
        to NULL, and this request must be invoked before committing the popup's
        initial state.

        See the documentation of xdg_popup for more details about what an
        xdg_popup is and how it is used.
      </description>
      <arg name="popup" type="object" interface="xdg_popup"/>
    </request>

    <request name="ack_configure">
      <description summary="ack a configure event">
        When a configure event is received, if a client commits the
        surface in response to the configure event, then the client
        must make an ack_configure request sometime before the commit
        request, passing along the serial of the configure event.

        If the client receives multiple configure events before it
        can respond to one, it only has to ack the last configure event.

        A client is not required to commit immediately after sending
        an ack_configure request - it may even ack_configure several times
        before its next surface commit.

        A client may send multiple ack_configure requests before committing, but
        only the last request sent before a commit indicates which configure
        event the client really is responding to.
      </description>
      <arg name="serial" type="uint" summary="the serial from the configure event"/>
    </request>

    <request name="destroy" type="destructor">
      <description summary="destroy the layer_surface">
        This request destroys the layer surface.
      </description>
    </request>

    <event name="configure">
      <description summary="suggest a surface change">
        The configure event asks the client to resize its surface.

        Clients should arrange their surface for the new states, and then send
        an ack_configure request with the serial sent in this configure event at
        some point before committing the new surface.

        The client is free to dismiss all but the last configure event it
        received.

        The width and height arguments specify the size of the window in
        surface-local coordinates.

        The size is a hint, in the sense that the client is free to ignore it if
        it doesn't resize, pick a smaller size (to satisfy aspect ratio or
        resize in steps of NxM pixels). If the client picks a smaller size and
        is anchored to two opposite anchors (e.g. 'top' and 'bottom'), the
        surface will be centered on this axis.

        If the width or height arguments are zero, it means the client should
        decide its own window dimension.
      </description>
      <arg name="serial" type="uint"/>
      <arg name="width" type="uint"/>
      <arg name="height" type="uint"/>
    </event>

    <event name="closed">
      <description summary="surface should be closed">
        The closed event is sent by the compositor when the surface will no
        longer be shown. The output may have been destroyed or the user may
        have asked for it to be removed. Further changes to the surface will be
        ignored. The client should destroy the resource after receiving this
        event, and create a new surface if they so choose.
      </description>
    </event>

    <enum name="error">
      <entry name="invalid_surface_state" value="0" summary="provided surface state is invalid"/>
      <entry name="invalid_size" value="1" summary="size is invalid"/>
      <entry name="invalid_anchor" value="2" summary="anchor bitfield is invalid"/>
      <entry name="invalid_keyboard_interactivity" value="3" summary="keyboard interactivity is invalid"/>
    </enum>

    <enum name="anchor" bitfield="true">
      <entry name="top" value="1" summary="the top edge of the anchor rectangle"/>
      <entry name="bottom" value="2" summary="the bottom edge of the anchor rectangle"/>
      <entry name="left" value="4" summary="the left edge of the anchor rectangle"/>
      <entry name="right" value="8" summary="the right edge of the anchor rectangle"/>
    </enum>

    <!-- Version 2 additions -->

    <request name="set_layer" since="2">
      <description summary="change the layer of the surface">
        Change the layer that the surface is rendered on.

        Layer is double-buffered, see wl_surface.commit.
      </description>
      <arg name="layer" type="uint" enum="zwlr_layer_shell_v1.layer" summary="layer to move this surface to"/>
    </request>
  </interface>
</protocol>