Struct ProcessContext 

#[non_exhaustive]
pub struct ProcessContext<'a> {
    pub transport: &'a TransportInfo,
    pub process_mode: ProcessMode,
    pub sample_rate: f64,
    pub block_size: usize,
    pub output_events: &'a mut EventList,
    /* private fields */
}

Per-block context handed to process(). Construct via Self::new + the with_* builders. Marked #[non_exhaustive] so adding host-populated fields in future (e.g. host_latency, bus_routing) isn’t a SemVer break for downstream pre-1.0 callers.

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

transport: &'a TransportInfo

process_mode: ProcessMode

How the host is driving audio this block. Tracks host toggles that don’t force a re-prepare (VST3 kRealtime <-> kPrefetch, an LV2 freewheel port). A plugin that reallocates for offline keys off AudioConfig::process_mode at reset instead; this field is for “may I relax realtime discipline right now?”.

sample_rate: f64

block_size: usize

output_events: &'a mut EventList

Implementations

impl<'a> ProcessContext<'a>

pub fn new( transport: &'a TransportInfo, sample_rate: f64, block_size: usize, output_events: &'a mut EventList, ) -> Self

pub fn with_process_mode(self, mode: ProcessMode) -> Self

Set the processing mode for this block. Defaults to ProcessMode::Realtime; wrappers stamp the live host mode.

pub fn with_params(self, f: &'a dyn Fn(u32) -> f64) -> Self

Set the parameter lookup callback.

pub fn with_meters(self, f: &'a dyn Fn(u32, f32)) -> Self

Set the meter reporting callback.

pub fn with_tasks(self, tasks: &'a AnyTaskSpawner) -> Self

Install the background-task spawner for this block. The shell stamps it when the plugin wired tasks: on plugin!.

pub fn tasks<T: Send + 'static>(&self) -> Option<TaskSpawner<T>>

The background-task spawner for task type T, or None if the plugin declared no tasks: lane of that type. Scheduling with the returned spawner is wait-free (see TaskSpawner::try_spawn / TaskSpawner::spawn_coalescing), so it is safe to call from the audio thread.

pub fn param(&self, id: u32) -> Option<f64>

Read a parameter’s plain value by ID.

Returns None when no params callback is wired up (e.g. when a plugin runs under the bare test driver without a with_params closure). Callers that always run inside a real format wrapper can .unwrap_or_default(). Distinguishing “no callback” from “value is zero” lets test harnesses notice when they forgot to wire up params rather than masking the misconfiguration as “host set the value to zero”.

pub fn set_meter(&self, id: impl Into<u32>, value: f32)

Report a meter value (0.0 to 1.0).