Struct ReadbackIndices 

pub struct ReadbackIndices { /* private fields */ }

A helper class used to manage the current slots for writing data from the render thread and reading it from the UI thread. Used mostly by hit-testing which needs to know the last transform of the visual

The lock is held for the whole duration of a write: begin_write returns a scope that owns the lock, and ReadbackWriteScope::end_write (or dropping the scope) completes the write and releases it. The revisions themselves are atomics and can be read from any thread without taking the lock, as the properties of the C# class can.

Unlike the C# monitor the lock is not reentrant: calling next_read, begin_write or lock on the thread that currently holds a write scope or a lock guard deadlocks.

Implementations

impl ReadbackIndices

pub fn new() -> Self

pub fn lock(&self) -> MutexGuard<'_, ()>

Takes the lock that guards the indices (the public _lock field of the C# class), blocking writes and next_read while the guard is alive.

pub fn read_revision(&self) -> u64

pub fn write_revision(&self) -> u64

pub fn last_completed_write(&self) -> u64

pub fn next_read(&self)

pub fn begin_write(&self) -> ReadbackWriteScope<'_>

Takes the lock and starts the next write revision. The write lasts until the returned scope is ended.

Trait Implementations

impl Default for ReadbackIndices

fn default() -> Self

Returns the “default value” for a type.