Commit 60f98db3 authored by Simon Ser's avatar Simon Ser
Browse files

ext-layer-shell: new protocol extension

The ext-layer-shell protocol can be used to allow clients to create
portable desktop components. It's been known for the last 3 years as
wlr-layer-shell [1]. It's now used by a number of clients and
compositors [2].


Signed-off-by: Simon Ser's avatarSimon Ser <>
parent 9b25b514
Pipeline #552213 passed with stages
in 1 minute and 10 seconds
......@@ -39,6 +39,7 @@ staging_protocols = {
'xdg-activation': ['v1'],
'drm-lease': ['v1'],
'ext-session-lock': ['v1'],
'ext-layer-shell': ['v1'],
protocol_files = []
ext-layer-shell protocol
Simon Ser <>
<?xml version="1.0" encoding="UTF-8"?>
<protocol name="ext_layer_shell_v1">
Copyright © 2017 Drew DeVault
Copyright © 2022 Simon Ser
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
<interface name="ext_layer_shell_v1" version="1">
<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.
<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"/>
<request name="destroy" type="destructor">
<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.
<request name="get_layer_surface">
<description summary="create a layer surface">
Create a layer surface for an existing wl_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, the client must send a set_layer
request to define the surface's layer. The client can send other
requests to setup the layer surface, and then 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.
<arg name="id" type="new_id" interface="ext_layer_surface_v1"/>
<arg name="surface" type="object" interface="wl_surface"/>
<arg name="output" type="object" interface="wl_output" allow-null="true"/>
<interface name="ext_layer_surface_v1" version="1">
<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
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.
<request name="destroy" type="destructor">
<description summary="destroy the layer surface">
This request destroys the layer surface.
<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"/>
<entry name="no_layer" value="4" summary="set_layer not sent before first commit"/>
<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.
<entry name="background" value="0"/>
<entry name="bottom" value="1"/>
<entry name="top" value="2"/>
<entry name="overlay" value="3"/>
<request name="set_layer">
<description summary="set the layer of the surface">
Set the layer of the surface.
Layer is double-buffered, see wl_surface.commit.
<arg name="layer" type="uint" enum="layer"/>
<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
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.
<arg name="width" type="int"/>
<arg name="height" type="int"/>
<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"/>
<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.
<arg name="anchor" type="uint" enum="anchor"/>
<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.
<arg name="zone" type="int"/>
<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.
<arg name="top" type="int"/>
<arg name="right" type="int"/>
<arg name="bottom" type="int"/>
<arg name="left" type="int"/>
<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.
<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.
<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
<entry name="on_demand" value="2">
<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
<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
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.
<arg name="keyboard_interactivity" type="uint" enum="keyboard_interactivity"/>
<request name="set_app_id">
<description summary="set application ID">
Set an application identifier for the surface.
The app ID identifies the general class of applications to which
the surface belongs. The compositor can use this to organize surfaces
of a given application differently, or fetch more metadata about the
As a best practice, it is suggested to select app ID's that match the
basename of the application's .desktop file. For example,
"org.freedesktop.FooViewer" where the .desktop file is
See the desktop-entry specification [0] for more details on
application identifiers and how they relate to .desktop files.
<arg name="app_id" type="string"/>
<request name="attach_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.
<arg name="popup" type="object" interface="xdg_popup"/>
<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.
<arg name="serial" type="uint" summary="the serial from the configure event"/>
<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
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.
<arg name="serial" type="uint"/>
<arg name="width" type="int"/>
<arg name="height" type="int"/>
<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.
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