Primary selection

Primary selection protocol

This protocol provides the ability to have a primary selection device to match that of the X server. This primary selection is a shortcut to the common clipboard selection, where text just needs to be selected in order to allow copying it elsewhere. The de facto way to perform this action is the middle mouse button, although it is not limited to this one.

Clients wishing to honor primary selection should create a primary selection source and set it as the selection through wp_primary_selection_device.set_selection whenever the text selection changes. In order to minimize calls in pointer-driven text selection, it should happen only once after the operation finished. Similarly, a NULL source should be set when text is unselected.

wp_primary_selection_offer objects are first announced through the wp_primary_selection_device.data_offer event. Immediately after this event, the primary data offer will emit wp_primary_selection_offer.offer events to let know of the mime types being offered.

When the primary selection changes, the client with the keyboard focus will receive wp_primary_selection_device.selection events. Only the client with the keyboard focus will receive such events with a non-NULL wp_primary_selection_offer. Across keyboard focus changes, previously focused clients will receive wp_primary_selection_device.events with a NULL wp_primary_selection_offer.

In order to request the primary selection data, the client must pass a recent serial pertaining to the press event that is triggering the operation, if the compositor deems the serial valid and recent, the wp_primary_selection_source.send event will happen in the other end to let the transfer begin. The client owning the primary selection should write the requested data, and close the file descriptor immediately.

If the primary selection owner client disappeared during the transfer, the client reading the data will receive a wp_primary_selection_device.selection event with a NULL wp_primary_selection_offer, the client should take this as a hint to finish the reads related to the no longer existing offer.

The primary selection owner should be checking for errors during writes, merely cancelling the ongoing transfer if any happened.

X primary selection emulation

The primary selection device manager is a singleton global object that provides access to the primary selection. It allows to create wp_primary_selection_source objects, as well as retrieving the per-seat wp_primary_selection_device objects.

create_source(id: new_id<zwp_primary_selection_source_v1>)
Argument
Type
Description
idnew_id<zwp_primary_selection_source_v1>
Create a new primary selection source

Create a new primary selection source.

get_device(id: new_id<zwp_primary_selection_device_v1>, seat: object<wl_seat>)
Argument
Type
Description
idnew_id<zwp_primary_selection_device_v1>
seatobject<wl_seat>
Create a new primary selection device

Create a new data device for a given seat.

destroy()
Destroy the primary selection device manager

Destroy the primary selection device manager.



set_selection(source: object<zwp_primary_selection_source_v1>, serial: uint)
Argument
Type
Description
sourceobject<zwp_primary_selection_source_v1>allow null
serialuint
serial of the event that triggered this request
Set the primary selection

Replaces the current selection. The previous owner of the primary selection will receive a wp_primary_selection_source.cancelled event.

To unset the selection, set the source to NULL.

destroy()
Destroy the primary selection device

Destroy the primary selection device.

Argument
Type
Description
offernew_id<zwp_primary_selection_offer_v1>
Introduce a new wp_primary_selection_offer

Introduces a new wp_primary_selection_offer object that may be used to receive the current primary selection. Immediately following this event, the new wp_primary_selection_offer object will send wp_primary_selection_offer.offer events to describe the offered mime types.

Argument
Type
Description
idobject<zwp_primary_selection_offer_v1>allow null
Advertise a new primary selection

The wp_primary_selection_device.selection event is sent to notify the client of a new primary selection. This event is sent after the wp_primary_selection.data_offer event introducing this object, and after the offer has announced its mimetypes through wp_primary_selection_offer.offer.

The data_offer is valid until a new offer or NULL is received or until the client loses keyboard focus. The client must destroy the previous selection data_offer, if any, upon receiving this event.


Offer to transfer primary selection contents

A wp_primary_selection_offer represents an offer to transfer the contents of the primary selection clipboard to the client. Similar to wl_data_offer, the offer also describes the mime types that the data can be converted to and provides the mechanisms for transferring the data directly to the client.

receive(mime_type: string, fd: fd)
Argument
Type
Description
mime_typestring
fdfd
Request that the data is transferred

To transfer the contents of the primary selection clipboard, the client issues this request and indicates the mime type that it wants to receive. The transfer happens through the passed file descriptor (typically created with the pipe system call). The source client writes the data in the mime type representation requested and then closes the file descriptor.

The receiving client reads from the read end of the pipe until EOF and closes its end, at which point the transfer is complete.

destroy()
Destroy the primary selection offer

Destroy the primary selection offer.

offer(mime_type: string)
Argument
Type
Description
mime_typestring
Advertise offered mime type

Sent immediately after creating announcing the wp_primary_selection_offer through wp_primary_selection_device.data_offer. One event is sent per offered mime type.


Offer to replace the contents of the primary selection

The source side of a wp_primary_selection_offer, it provides a way to describe the offered data and respond to requests to transfer the requested contents of the primary selection clipboard.

offer(mime_type: string)
Argument
Type
Description
mime_typestring
Add an offered mime type

This request adds a mime type to the set of mime types advertised to targets. Can be called several times to offer multiple types.

destroy()
Destroy the primary selection source

Destroy the primary selection source.

send(mime_type: string, fd: fd)
Argument
Type
Description
mime_typestring
fdfd
Send the primary selection contents

Request for the current primary selection contents from the client. Send the specified mime type over the passed file descriptor, then close it.

cancelled()
Request for primary selection contents was canceled

This primary selection source is no longer valid. The client should clean up and destroy this primary selection source.


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