<protocol name="fullscreen_shell">

  <interface name="_wl_fullscreen_shell" version="1">

    <description summary="Displays a single surface per output">

      Displays a single surface per output.

      This interface provides a mechanism for a single client to display

      simple full-screen surfaces.  While there technically may be multiple

      clients bound to this interface, only one of those clients should be

      shown at a time.

      To present a surface, the client uses either the present_surface or

      present_surface_for_mode requests.  Presenting a surface takes effect

      on the next wl_surface.commit.  See the individual requests for

      details about scaling and mode switches.

      The client can have at most one surface per output at any time.

      Requesting a surface be presented on an output that already has a

      surface replaces the previously presented surface.  Presenting a null

      surface removes its content and effectively disables the output.

      Exactly what happens when an output is "disabled" is

      compositor-specific.  The same surface may be presented on multiple

      outputs simultaneously.

      Once a surface is presented on an output, it stays on that output

      until either the client removes it or the compositor destroys the

      output.  This way, the client can update the output's contents by

      simply attaching a new buffer.

    </description>

    <request name="release" type="destructor">

      <description summary="release the wl_fullscreen_shell interface">

	Release the binding from the wl_fullscreen_shell interface

	This destroys the server-side object and frees this binding.  If

	the client binds to wl_fullscreen_shell multiple times, it may wish

	to free some of those bindings.

      </description>

    </request>

    <enum name="capability">

      <description summary="capabilities advertised by the compositor">

	Various capabilities that can be advertised by the compositor.  They

	are advertised one-at-a-time when the wl_fullscreen_shell interface is

	bound.  See the wl_fullscreen_shell.capability event for more details.

	ARBITRARY_MODE:

	This is a hint to the client that indicates that the compositor is

	capable of setting practically any mode on its outputs.  If this

	capability is provided, wl_fullscreen_shell.present_surface_for_mode

	will almost never fail and clients should feel free to set whatever

	mode they like.  If the compositor does not advertise this, it may

	still support some modes that are not advertised through wl_global.mode

	but it is less likely.

	CURSOR_PLANE:

	This is a hint to the client that indicates that the compositor can

	handle a cursor surface from the client without actually compositing.

	This may be because of a hardware cursor plane or some other mechanism.

	If the compositor does not advertise this capability then setting

	wl_pointer.cursor may degrade performance or be ignored entirely.  If

	CURSOR_PLANE is not advertised, it is recommended that the client draw

	its own cursor and set wl_pointer.cursor(NULL).

      </description>

      <entry name="arbitrary_modes" value="1" summary="compositor is capable of almost any output mode"/>

      <entry name="cursor_plane" value="2" summary="compositor has a separate cursor plane"/>

    </enum>

    <event name="capability">

      <description summary="advertises a capability of the compositor">

	Advertises a single capability of the compositor.

	When the wl_fullscreen_shell interface is bound, this event is emitted

	once for each capability advertised.  Valid capabilities are given by

	the wl_fullscreen_shell.capability enum.  If clients want to take

	advantage of any of these capabilities, they should use a

	wl_display.sync request immediately after binding to ensure that they

	receive all the capability events.

      </description>

      <arg name="capabilty" type="uint"/>

    </event>

    <enum name="present_method">

      <description summary="different method to set the surface fullscreen">

	Hints to indicate to the compositor how to deal with a conflict

	between the dimensions of the surface and the dimensions of the

	output. The compositor is free to ignore this parameter.

      </description>

      <entry name="default" value="0" summary="no preference, apply default policy"/>

      <entry name="center" value="1" summary="center the surface on the output"/>

      <entry name="zoom" value="2" summary="scale the surface, preserving aspect ratio, to the largest size that will fit on the output" />

      <entry name="zoom_crop" value="3" summary="scale the surface, preserving aspect ratio, to fully fill the output cropping if needed" />

      <entry name="stretch" value="4" summary="scale the surface to the size of the output ignoring aspect ratio" />

    </enum>

    <request name="present_surface">

      <description summary="present surface for display">

	Present a surface on the given output.

	If the output is null, the compositor will present the surface on

	whatever display (or displays) it thinks best.  In particular, this

	may replace any or all surfaces currently presented so it should

	not be used in combination with placing surfaces on specific

	outputs.

	The method parameter is a hint to the compositor for how the surface

	is to be presented.  In particular, it tells the compositor how to

	handle a size mismatch between the presented surface and the

	output.  The compositor is free to ignore this parameter.

	The "zoom", "zoom_crop", and "stretch" methods imply a scaling

	operation on the surface.  This will override any kind of output

	scaling, so the buffer_scale property of the surface is effectively

	ignored.

      </description>

      <arg name="surface" type="object" interface="wl_surface" allow-null="true"/>

      <arg name="method" type="uint"/>

      <arg name="output" type="object" interface="wl_output" allow-null="true"/>

    </request>

    <request name="present_surface_for_mode">

      <description summary="present surface for display at a particular mode">

	Presents a surface on the given output for a particular mode.

	If the current size of the output differs from that of the surface,

	the compositor will attempt to change the size of the output to

	match the surface.  The result of the mode-switch operation will be

	returned via the provided wl_fullscreen_shell_mode_feedback object.

	If the current output mode matches the one requested or if the

	compositor successfully switches the mode to match the surface,

	then the mode_successful event will be sent and the output will

	contain the contents of the given surface.  If the compositor

	cannot match the output size to the surface size, the mode_failed

	will be sent and the output will contain the contents of the

	previously presented surface (if any).  If another surface is

	presented on the given output before either of these has a chance

	to happen, the present_cancelled event will be sent.

	Due to race conditions and other issues unknown to the client, no

	mode-switch operation is guaranteed to succeed.  However, if the

	mode is one advertised by wl_output.mode or if the compositor

	advertises the ARBITRARY_MODES capability, then the client should

	expect that the mode-switch operation will usually succeed.

	If the size of the presented surface changes, the resulting output

	is undefined.  The compositor may attempt to change the output mode

	to compensate.  However, there is no guarantee that a suitable mode

	will be found and the client has no way to be notified of success

	or failure.

	The framerate parameter specifies the desired framerate for the

	output in mHz.  The compositor is free to ignore this parameter.  A

	value of 0 indicates that the client has no preference.

	If the value of wl_output.scale differs from wl_surface.buffer_scale,

	then the compositor may choose a mode that matches either the buffer

	size or the surface size.  In either case, the surface will fill the

	output.

      </description>

      <arg name="surface" type="object" interface="wl_surface"/>

      <arg name="output" type="object" interface="wl_output"/>

      <arg name="framerate" type="int"/>

      <arg name="feedback" type="new_id" interface="_wl_fullscreen_shell_mode_feedback"/>

    </request>

    <enum name="error">

      <description summary="wl_fullscreen_shell error values">

	These errors can be emitted in response to wl_fullscreen_shell requests

      </description>

      <entry name="invalid_method" value="0" summary="present_method is not known"/>

    </enum>

  </interface>

  <interface name="_wl_fullscreen_shell_mode_feedback" version="1">

    <event name="mode_successful">

      <description summary="mode switch succeeded">

	This event indicates that the attempted mode switch operation was

	successful.  A surface of the size requested in the mode switch

	will fill the output without scaling.

	Upon receiving this event, the client should destroy the

	wl_fullscreen_shell_mode_feedback object.

      </description>

    </event>

    <event name="mode_failed">

      <description summary="mode switch failed">

	This event indicates that the attempted mode switch operation

	failed. This may be because the requested output mode is not

	possible or it may mean that the compositor does not want to allow it.

	Upon receiving this event, the client should destroy the

	wl_fullscreen_shell_mode_feedback object.

      </description>

    </event>

    <event name="present_cancelled">

      <description summary="mode switch cancelled">

	This event indicates that the attempted mode switch operation was

	cancelled.  Most likely this is because the client requested a

	second mode switch before the first one completed.

	Upon receiving this event, the client should destroy the

	wl_fullscreen_shell_mode_feedback object.

      </description>

    </event>

  </interface>

</protocol>