wp_viewporter

version 1
Surface cropping and scaling

The global interface exposing surface cropping and scaling capabilities is used to instantiate an interface extension for a wl_surface object. This extended interface will then allow cropping and scaling the surface contents, effectively disconnecting the direct relationship between the buffer and the surface size.

destroy
Type: destructor
destroy()
Unbind from the cropping and scaling interface

Informs the server that the client will not be using this protocol object anymore. This does not affect any other objects, wp_viewport objects included.

get_viewport(id: new_id<wp_viewport>, surface: object<wl_surface>)
Argument
Type
Description
idnew_id<wp_viewport>
the new viewport interface id
surfaceobject<wl_surface>
the surface
Extend surface interface for crop and scale

Instantiate an interface extension for the given wl_surface to crop and scale its content. If the given wl_surface already has a wp_viewport object associated, the viewport_exists protocol error is raised.

error { viewport_exists } 
Argument
Value
Description
viewport_exists0
the surface already has a viewport object associated

wp_viewport

version 1
Crop and scale interface to a wl_surface

An additional interface to a wl_surface object, which allows the client to specify the cropping and scaling of the surface contents.

This interface works with two concepts: the source rectangle (src_x, src_y, src_width, src_height), and the destination size (dst_width, dst_height). The contents of the source rectangle are scaled to the destination size, and content outside the source rectangle is ignored. This state is double-buffered, and is applied on the next wl_surface.commit.

The two parts of crop and scale state are independent: the source rectangle, and the destination size. Initially both are unset, that is, no scaling is applied. The whole of the current wl_buffer is used as the source, and the surface size is as defined in wl_surface.attach.

If the destination size is set, it causes the surface size to become dst_width, dst_height. The source (rectangle) is scaled to exactly this size. This overrides whatever the attached wl_buffer size is, unless the wl_buffer is NULL. If the wl_buffer is NULL, the surface has no content and therefore no size. Otherwise, the size is always at least 1x1 in surface local coordinates.

If the source rectangle is set, it defines what area of the wl_buffer is taken as the source. If the source rectangle is set and the destination size is not set, then src_width and src_height must be integers, and the surface size becomes the source rectangle size. This results in cropping without scaling. If src_width or src_height are not integers and destination size is not set, the bad_size protocol error is raised when the surface state is applied.

The coordinate transformations from buffer pixel coordinates up to the surface-local coordinates happen in the following order: 1. buffer_transform (wl_surface.set_buffer_transform) 2. buffer_scale (wl_surface.set_buffer_scale) 3. crop and scale (wp_viewport.set*) This means, that the source rectangle coordinates of crop and scale are given in the coordinates after the buffer transform and scale, i.e. in the coordinates that would be the surface-local coordinates if the crop and scale was not applied.

If src_x or src_y are negative, the bad_value protocol error is raised. Otherwise, if the source rectangle is partially or completely outside of the non-NULL wl_buffer, then the out_of_buffer protocol error is raised when the surface state is applied. A NULL wl_buffer does not raise the out_of_buffer error.

If the wl_surface associated with the wp_viewport is destroyed, all wp_viewport requests except 'destroy' raise the protocol error no_surface.

If the wp_viewport object is destroyed, the crop and scale state is removed from the wl_surface. The change will be applied on the next wl_surface.commit.

destroy
Type: destructor
destroy()
Remove scaling and cropping from the surface

The associated wl_surface's crop and scale state is removed. The change is applied on the next wl_surface.commit.

set_source(x: fixed, y: fixed, width: fixed, height: fixed)
Argument
Type
Description
xfixed
source rectangle x
yfixed
source rectangle y
widthfixed
source rectangle width
heightfixed
source rectangle height
Set the source rectangle for cropping

Set the source rectangle of the associated wl_surface. See wp_viewport for the description, and relation to the wl_buffer size.

If all of x, y, width and height are -1.0, the source rectangle is unset instead. Any other set of values where width or height are zero or negative, or x or y are negative, raise the bad_value protocol error.

The crop and scale state is double-buffered state, and will be applied on the next wl_surface.commit.

set_destination(width: int, height: int)
Argument
Type
Description
widthint
surface width
heightint
surface height
Set the surface size for scaling

Set the destination size of the associated wl_surface. See wp_viewport for the description, and relation to the wl_buffer size.

If width is -1 and height is -1, the destination size is unset instead. Any other pair of values for width and height that contains zero or negative values raises the bad_value protocol error.

The crop and scale state is double-buffered state, and will be applied on the next wl_surface.commit.

Argument
Value
Description
bad_value0
negative or zero values in width or height
bad_size1
destination size is not integer
out_of_buffer2
source rectangle extends outside of the content area
no_surface3
the wl_surface was destroyed

Compositor Support

Mutter
Mutter
45.4
KWin
KWin
6.0.1
Sway
Sway
1.9
Hyprland
Hyprland
0.35
Weston
Weston
13
Mir
Mir
...
GameScope
GameScope
...
wp_viewporter
1
1
1
1
1
x
x

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