Enum wayland_protocols::wp::presentation_time::server::wp_presentation_feedback::Event

#[non_exhaustive]
pub enum Event<'a> {
    SyncOutput {
        output: WlOutput,
    },
    Presented {
        tv_sec_hi: u32,
        tv_sec_lo: u32,
        tv_nsec: u32,
        refresh: u32,
        seq_hi: u32,
        seq_lo: u32,
        flags: WEnum<Kind>,
    },
    Discarded,
}

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

SyncOutput

presentation synchronized to this output

As presentation can be synchronized to only one output at a time, this event tells which output it was. This event is only sent prior to the presented event.

As clients may bind to the same global wl_output multiple times, this event is sent for each bound instance that matches the synchronized output. If a client has not bound to the right wl_output global at all, this event is not sent.

Fields

output: WlOutput

presentation output

Presented

the content update was displayed

The associated content update was displayed to the user at the indicated time (tv_sec_hi/lo, tv_nsec). For the interpretation of the timestamp, see presentation.clock_id event.

The timestamp corresponds to the time when the content update turned into light the first time on the surface’s main output. Compositors may approximate this from the framebuffer flip completion events from the system, and the latency of the physical display path if known.

This event is preceded by all related sync_output events telling which output’s refresh cycle the feedback corresponds to, i.e. the main output for the surface. Compositors are recommended to choose the output containing the largest part of the wl_surface, or keeping the output they previously chose. Having a stable presentation output association helps clients predict future output refreshes (vblank).

The ‘refresh’ argument gives the compositor’s prediction of how many nanoseconds after tv_sec, tv_nsec the very next output refresh may occur. This is to further aid clients in predicting future refreshes, i.e., estimating the timestamps targeting the next few vblanks. If such prediction cannot usefully be done, the argument is zero.

For version 2 and later, if the output does not have a constant refresh rate, explicit video mode switches excluded, then the refresh argument must be either an appropriate rate picked by the compositor (e.g. fastest rate), or 0 if no such rate exists. For version 1, if the output does not have a constant refresh rate, the refresh argument must be zero.

The 64-bit value combined from seq_hi and seq_lo is the value of the output’s vertical retrace counter when the content update was first scanned out to the display. This value must be compatible with the definition of MSC in GLX_OML_sync_control specification. Note, that if the display path has a non-zero latency, the time instant specified by this counter may differ from the timestamp’s.

If the output does not have a concept of vertical retrace or a refresh cycle, or the output device is self-refreshing without a way to query the refresh count, then the arguments seq_hi and seq_lo must be zero.

This is a destructor, once sent this object cannot be used any longer.

Fields

tv_sec_hi: u32

high 32 bits of the seconds part of the presentation timestamp

tv_sec_lo: u32

low 32 bits of the seconds part of the presentation timestamp

tv_nsec: u32

nanoseconds part of the presentation timestamp

refresh: u32

nanoseconds till next refresh

seq_hi: u32

high 32 bits of refresh counter

seq_lo: u32

low 32 bits of refresh counter

flags: WEnum<Kind>

combination of ‘kind’ values

Discarded

the content update was not displayed

The content update was never displayed to the user.

This is a destructor, once sent this object cannot be used any longer.

Implementations

impl<'a> Event<'a>

pub fn opcode(&self) -> u16

Get the opcode number of this message

Trait Implementations

impl<'a> Debug for Event<'a>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.