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A.13. wl_shell_surface - desktop-style metadata interface

An interface that may be implemented by a wl_surface, for implementations that provide a desktop-style user interface.
It provides requests to treat surfaces like toplevel, fullscreen or popup windows, move, resize or maximize them, associate metadata like title and class, etc.
On the server side the object is automatically destroyed when the related wl_surface is destroyed. On client side, wl_shell_surface_destroy() must be called before destroying the wl_surface object.

A.13.1. Requests provided by wl_shell_surface

A.13.1.1. wl_shell_surface::pong - respond to a ping event

A client must respond to a ping event with a pong request or the client may be deemed unresponsive.

wl_shell_surface::pong arguments

serial
Type: uint
serial of the ping event

A.13.1.2. wl_shell_surface::move - start an interactive move

Start a pointer-driven move of the surface.
This request must be used in response to a button press event. The server may ignore move requests depending on the state of the surface (e.g. fullscreen or maximized).

wl_shell_surface::move arguments

seat
Type: object
the wl_seat whose pointer is used
serial
Type: uint
serial of the implicit grab on the pointer

A.13.1.3. wl_shell_surface::resize - start an interactive resize

Start a pointer-driven resizing of the surface.
This request must be used in response to a button press event. The server may ignore resize requests depending on the state of the surface (e.g. fullscreen or maximized).

wl_shell_surface::resize arguments

seat
Type: object
the wl_seat whose pointer is used
serial
Type: uint
serial of the implicit grab on the pointer
edges
Type: uint
which edge or corner is being dragged

A.13.1.4. wl_shell_surface::set_toplevel - make the surface a toplevel surface

Map the surface as a toplevel surface.
A toplevel surface is not fullscreen, maximized or transient.

A.13.1.5. wl_shell_surface::set_transient - make the surface a transient surface

Map the surface relative to an existing surface.
The x and y arguments specify the locations of the upper left corner of the surface relative to the upper left corner of the parent surface, in surface local coordinates.
The flags argument controls details of the transient behaviour.

wl_shell_surface::set_transient arguments

parent
Type: object
x
Type: int
y
Type: int
flags
Type: uint

A.13.1.6. wl_shell_surface::set_fullscreen - make the surface a fullscreen surface

Map the surface as a fullscreen surface.
If an output parameter is given then the surface will be made fullscreen on that output. If the client does not specify the output then the compositor will apply its policy - usually choosing the output on which the surface has the biggest surface area.
The client may specify a method to resolve a size conflict between the output size and the surface size - this is provided through the method parameter.
The framerate parameter is used only when the method is set to "driver", to indicate the preferred framerate. A value of 0 indicates that the app does not care about framerate. The framerate is specified in mHz, that is framerate of 60000 is 60Hz.
A method of "scale" or "driver" implies a scaling operation of the surface, either via a direct scaling operation or a change of the output mode. This will override any kind of output scaling, so that mapping a surface with a buffer size equal to the mode can fill the screen independent of buffer_scale.
A method of "fill" means we don't scale up the buffer, however any output scale is applied. This means that you may run into an edge case where the application maps a buffer with the same size of the output mode but buffer_scale 1 (thus making a surface larger than the output). In this case it is allowed to downscale the results to fit the screen.
The compositor must reply to this request with a configure event with the dimensions for the output on which the surface will be made fullscreen.

wl_shell_surface::set_fullscreen arguments

method
Type: uint
framerate
Type: uint
output
Type: object

A.13.1.7. wl_shell_surface::set_popup - make the surface a popup surface

Map the surface as a popup.
A popup surface is a transient surface with an added pointer grab.
An existing implicit grab will be changed to owner-events mode, and the popup grab will continue after the implicit grab ends (i.e. releasing the mouse button does not cause the popup to be unmapped).
The popup grab continues until the window is destroyed or a mouse button is pressed in any other clients window. A click in any of the clients surfaces is reported as normal, however, clicks in other clients surfaces will be discarded and trigger the callback.
The x and y arguments specify the locations of the upper left corner of the surface relative to the upper left corner of the parent surface, in surface local coordinates.

wl_shell_surface::set_popup arguments

seat
Type: object
the wl_seat whose pointer is used
serial
Type: uint
serial of the implicit grab on the pointer
parent
Type: object
x
Type: int
y
Type: int
flags
Type: uint

A.13.1.8. wl_shell_surface::set_maximized - make the surface a maximized surface

Map the surface as a maximized surface.
If an output parameter is given then the surface will be maximized on that output. If the client does not specify the output then the compositor will apply its policy - usually choosing the output on which the surface has the biggest surface area.
The compositor will reply with a configure event telling the expected new surface size. The operation is completed on the next buffer attach to this surface.
A maximized surface typically fills the entire output it is bound to, except for desktop element such as panels. This is the main difference between a maximized shell surface and a fullscreen shell surface.
The details depend on the compositor implementation.

wl_shell_surface::set_maximized arguments

output
Type: object

A.13.1.9. wl_shell_surface::set_title - set surface title

Set a short title for the surface.
This string may be used to identify the surface in a task bar, window list, or other user interface elements provided by the compositor.
The string must be encoded in UTF-8.

wl_shell_surface::set_title arguments

title
Type: string

A.13.1.10. wl_shell_surface::set_class - set surface class

Set a class for the surface.
The surface class identifies the general class of applications to which the surface belongs. A common convention is to use the file name (or the full path if it is a non-standard location) of the application's .desktop file as the class.

wl_shell_surface::set_class arguments

class_
Type: string

A.13.2. Events provided by wl_shell_surface

A.13.2.1. wl_shell_surface::ping - ping client

Ping a client to check if it is receiving events and sending requests. A client is expected to reply with a pong request.

wl_shell_surface::ping arguments

serial
Type: uint

A.13.2.2. wl_shell_surface::configure - suggest resize

The configure event asks the client to resize its surface.
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).
The edges parameter provides a hint about how the surface was resized. The client may use this information to decide how to adjust its content to the new size (e.g. a scrolling area might adjust its content position to leave the viewable content unmoved).
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.

wl_shell_surface::configure arguments

edges
Type: uint
width
Type: int
height
Type: int

A.13.2.3. wl_shell_surface::popup_done - popup interaction is done

The popup_done event is sent out when a popup grab is broken, that is, when the user clicks a surface that doesn't belong to the client owning the popup surface.

A.13.3. Enums provided by wl_shell_surface

A.13.3.1. wl_shell_surface::resize - edge values for resizing

These values are used to indicate which edge of a surface is being dragged in a resize operation. The server may use this information to adapt its behavior, e.g. choose an appropriate cursor image.

wl_shell_surface::resize values

none
Value: 0
top
Value: 1
bottom
Value: 2
left
Value: 4
top_left
Value: 5
bottom_left
Value: 6
right
Value: 8
top_right
Value: 9
bottom_right
Value: 10

A.13.3.2. wl_shell_surface::transient - details of transient behaviour

These flags specify details of the expected behaviour of transient surfaces. Used in the set_transient request.

wl_shell_surface::transient values

inactive
Value: 0x1
do not set keyboard focus

A.13.3.3. wl_shell_surface::fullscreen_method - 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.

wl_shell_surface::fullscreen_method values

default
Value: 0
no preference, apply default policy
scale
Value: 1
scale, preserve the surface's aspect ratio and center on output
driver
Value: 2
switch output mode to the smallest mode that can fit the surface, add black borders to compensate size mismatch
fill
Value: 3
no upscaling, center on output and add black borders to compensate size mismatch