Struct PingPong 

pub struct PingPong { /* private fields */ }

Which of two cursor buffers is live.

Implementations

impl PingPong

pub const fn new() -> Self

A fresh pair, buffer 0 live.

pub const fn single() -> Self

A single buffer, for the legacy path.

The legacy ioctls take one buffer handle and have no flip to alternate on, so a second buffer buys nothing there.

pub const fn active(self) -> usize

The buffer scanout is reading.

pub const fn draw_target(self) -> usize

The buffer to draw the next frame into.

The one that is not on screen, so drawing cannot tear. With a single buffer there is no choice, and the tear is accepted: the legacy path redraws the buffer the CRTC is showing, which only a new shape or an animation frame does.

pub const fn commit_target(self) -> usize

The buffer the next commit should publish.

Whatever was just drawn, if anything was. A commit that only moves the cursor re-publishes the buffer already on screen rather than flipping to a stale one.

pub const fn mark_drawn(&mut self)

Note that a frame has been drawn into PingPong::draw_target.

pub const fn has_undrawn(self) -> bool

Whether a draw is waiting to reach the screen.

pub const fn published(&mut self)

Note that a commit published PingPong::commit_target.

The buffer just published becomes the live one, so the next draw goes to the one now safely off screen.

Call this on a commit that landed. Where the caller owns the commit there is no way to know, and calling it optimistically is the right trade: if their commit failed, scanout is still reading the buffer this just marked as the draw target, and the next draw there can tear — which is exactly what a single buffer does all the time. A successful commit, the overwhelmingly common case, is tear-free.

Trait Implementations

impl Clone for PingPong

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for PingPong

impl Debug for PingPong

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

Formats the value using the given formatter.

impl Default for PingPong

fn default() -> Self

Returns the “default value” for a type.

impl Eq for PingPong

impl PartialEq for PingPong

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for PingPong