Struct AUParameter

#[repr(C)]
pub struct AUParameter { /* private fields */ }

Available on crate feature AUParameters only.

A node representing a single parameter.

See also Apple’s documentation

Implementations

impl AUParameter

pub unsafe fn minValue(&self) -> AUValue

The parameter’s minimum value.

pub unsafe fn maxValue(&self) -> AUValue

The parameter’s maximum value.

pub unsafe fn unit(&self) -> AudioUnitParameterUnit

Available on crate feature AudioUnitProperties only.

The parameter’s unit of measurement.

pub unsafe fn unitName(&self) -> Option<Retained<NSString>>

A localized name for the parameter’s unit. Supplied by the AU if kAudioUnitParameterUnit_CustomUnit; else by the framework.

pub unsafe fn flags(&self) -> AudioUnitParameterOptions

Available on crate feature AudioUnitProperties only.

Various details of the parameter.

pub unsafe fn address(&self) -> AUParameterAddress

The parameter’s address.

pub unsafe fn valueStrings(&self) -> Option<Retained<NSArray<NSString>>>

For parameters with kAudioUnitParameterUnit_Indexed, localized strings corresponding to the values.

pub unsafe fn dependentParameters(&self) -> Option<Retained<NSArray<NSNumber>>>

Parameters whose values may change as a side effect of this parameter’s value changing.

Each array value is an NSNumber representing AUParameterAddress.

pub unsafe fn value(&self) -> AUValue

The parameter’s current value.

pub unsafe fn setValue(&self, value: AUValue)

Setter for value.

pub unsafe fn setValue_originator( &self, value: AUValue, originator: AUParameterObserverToken, )

Set the parameter’s value, avoiding redundant notifications to the originator.

Bridged to the v2 function AudioUnitSetParameter.

pub unsafe fn setValue_originator_atHostTime( &self, value: AUValue, originator: AUParameterObserverToken, host_time: u64, )

Convenience for setValue:originator:atHostTime:eventType:

Bridged to the v2 function AudioUnitSetParameter.

pub unsafe fn setValue_originator_atHostTime_eventType( &self, value: AUValue, originator: AUParameterObserverToken, host_time: u64, event_type: AUParameterAutomationEventType, )

Set the parameter’s value, preserving the host time of the gesture that initiated the change, and associating an event type such as touch/release.

In general, this method should only be called from a user interface. It initiates a change to a parameter in a way that captures the gesture such that it can be recorded later – any AUParameterAutomationObservers will receive the host time and event type associated with the parameter change.

From an audio playback engine, a host should schedule automated parameter changes through AUAudioUnit’s scheduleParameterBlock.

Bridged to the v2 function AudioUnitSetParameter.

pub unsafe fn stringFromValue( &self, value: *const AUValue, ) -> Retained<NSString>

Get a textual representation of a value for the parameter. Use value==nil to use the current value. Bridged to the v2 property kAudioUnitProperty_ParameterStringFromValue.

This is currently only supported for parameters whose flags include kAudioUnitParameterFlag_ValuesHaveStrings.

pub unsafe fn valueFromString(&self, string: &NSString) -> AUValue

Convert a textual representation of a value to a numeric one.

This is currently only supported for parameters whose flags include kAudioUnitParameterFlag_ValuesHaveStrings.

impl AUParameter

Methods declared on superclass NSObject.

pub unsafe fn init(this: Allocated<Self>) -> Retained<Self>

pub unsafe fn new() -> Retained<Self>

Methods from Deref<Target = AUParameterNode>

pub unsafe fn implementorValueObserver(&self) -> AUImplementorValueObserver

Available on crate features AUAudioUnitImplementation and block2 only.

Called when a parameter changes value.

This block, used only in an audio unit implementation, receives all externally-generated changes to parameter values. It should store the new value in its audio signal processing state (assuming that that state is separate from the AUParameter object).

pub unsafe fn setImplementorValueObserver( &self, implementor_value_observer: AUImplementorValueObserver, )

Available on crate features AUAudioUnitImplementation and block2 only.

Setter for implementorValueObserver.

pub unsafe fn implementorValueProvider(&self) -> AUImplementorValueProvider

Available on crate features AUAudioUnitImplementation and block2 only.

Called when a value of a parameter in the tree is known to have a stale value needing to be refreshed.

The audio unit should return the current value for this parameter; the AUParameterNode will store the value.

pub unsafe fn setImplementorValueProvider( &self, implementor_value_provider: AUImplementorValueProvider, )

Available on crate features AUAudioUnitImplementation and block2 only.

Setter for implementorValueProvider.

pub unsafe fn implementorStringFromValueCallback( &self, ) -> AUImplementorStringFromValueCallback

Available on crate features AUAudioUnitImplementation and block2 only.

Called to provide string representations of parameter values. If value is nil, the callback uses the current value of the parameter.

pub unsafe fn setImplementorStringFromValueCallback( &self, implementor_string_from_value_callback: AUImplementorStringFromValueCallback, )

Available on crate features AUAudioUnitImplementation and block2 only.

Setter for implementorStringFromValueCallback.

pub unsafe fn implementorValueFromStringCallback( &self, ) -> AUImplementorValueFromStringCallback

Available on crate features AUAudioUnitImplementation and block2 only.

Called to convert string to numeric representations of parameter values.

pub unsafe fn setImplementorValueFromStringCallback( &self, implementor_value_from_string_callback: AUImplementorValueFromStringCallback, )

Available on crate features AUAudioUnitImplementation and block2 only.

Setter for implementorValueFromStringCallback.

pub unsafe fn implementorDisplayNameWithLengthCallback( &self, ) -> AUImplementorDisplayNameWithLengthCallback

Available on crate features AUAudioUnitImplementation and block2 only.

Called to obtain an abbreviated version of a parameter or group name.

pub unsafe fn setImplementorDisplayNameWithLengthCallback( &self, implementor_display_name_with_length_callback: AUImplementorDisplayNameWithLengthCallback, )

Available on crate features AUAudioUnitImplementation and block2 only.

Setter for implementorDisplayNameWithLengthCallback.

pub unsafe fn identifier(&self) -> Retained<NSString>

A non-localized, permanent name for a parameter or group.

The identifier must be unique for all child nodes under any given parent. From release to release, an audio unit must not change its parameters’ identifiers; this will invalidate any hosts’ documents that refer to the parameters.

pub unsafe fn keyPath(&self) -> Retained<NSString>

Generated by concatenating the identifiers of a node’s parents with its own.

Unless an audio unit specifically documents that its parameter addresses are stable and persistent, hosts, when recording parameter values, should bind to the keyPath.

The individual node identifiers in a key path are separated by periods. (“.”)

Passing a node’s keyPath to -[tree valueForKeyPath:] should return the same node.

pub unsafe fn displayName(&self) -> Retained<NSString>

A localized name to display for the parameter.

pub unsafe fn displayNameWithLength( &self, maximum_length: NSInteger, ) -> Retained<NSString>

A version of displayName possibly abbreviated to the given desired length, in characters.

The default implementation simply returns displayName.

pub unsafe fn tokenByAddingParameterObserver( &self, observer: AUParameterObserver, ) -> AUParameterObserverToken

Available on crate feature block2 only.

Add an observer for a parameter or all parameters in a group/tree.

An audio unit view can use an AUParameterObserver to be notified of changes to a single parameter, or to all parameters in a group/tree.

These callbacks are throttled so as to limit the rate of redundant notifications in the case of frequent changes to a single parameter.

This block is called in an arbitrary thread context. It is responsible for thread-safety. It must not make any calls to add or remove other observers, including itself; this will deadlock.

An audio unit’s implementation should interact with the parameter object via implementorValueObserver and implementorValueProvider.

Parameter observers are bound to a specific parameter instance. If this parameter is destroyed, e.g. if the parameter tree is re-constructed, the previously set parameter observers will no longer be valid. Clients can observe changes to the parameter tree via KVO. See the discussion of -[AUAudioUnit parameterTree].

Parameter observer: A block to call after the value of a parameter has changed.

Returns: A token which can be passed to removeParameterObserver: or to -[AUParameter setValue:originator:]

pub unsafe fn tokenByAddingParameterRecordingObserver( &self, observer: AUParameterRecordingObserver, ) -> AUParameterObserverToken

Available on crate feature block2 only.

Add a recording observer for a parameter or all parameters in a group/tree.

This is a variant of tokenByAddingParameterAutomationObserver where the callback receives AURecordedParameterEvents instead of AUParameterAutomationEvents.

This will be deprecated in favor of tokenByAddingParameterAutomationObserver in a future release.

pub unsafe fn tokenByAddingParameterAutomationObserver( &self, observer: AUParameterAutomationObserver, ) -> AUParameterObserverToken

Available on crate feature block2 only.

Add a recording observer for a parameter or all parameters in a group/tree.

An audio unit host can use an AUParameterAutomationObserver or AUParameterRecordingObserver to capture a series of changes to a parameter value, including the timing of the events, as generated by a UI gesture in a view, for example.

Unlike AUParameterObserver, these callbacks are not throttled.

This block is called in an arbitrary thread context. It is responsible for thread-safety. It must not make any calls to add or remove other observers, including itself; this will deadlock.

An audio unit’s engine should interact with the parameter object via implementorValueObserver and implementorValueProvider.

Parameter observer: A block to call to record the changing of a parameter value.

Returns: A token which can be passed to removeParameterObserver: or to -[AUParameter setValue:originator:]

pub unsafe fn removeParameterObserver(&self, token: AUParameterObserverToken)

Remove an observer created with tokenByAddingParameterObserver, tokenByAddingParameterRecordingObserver, or tokenByAddingParameterAutomationObserver.

This call will remove the callback corresponding to the supplied token. Note that this will block until any callbacks currently in flight have completed.

Methods from Deref<Target = NSObject>

pub fn doesNotRecognizeSelector(&self, sel: Sel) -> !

Handle messages the object doesn’t recognize.

See Apple’s documentation for details.

Methods from Deref<Target = AnyObject>

pub fn class(&self) -> &'static AnyClass

Dynamically find the class of this object.

Panics

May panic if the object is invalid (which may be the case for objects returned from unavailable init/new methods).

Example

Check that an instance of NSObject has the precise class NSObject.

use objc2::ClassType;
use objc2::runtime::NSObject;

let obj = NSObject::new();
assert_eq!(obj.class(), NSObject::class());

pub unsafe fn get_ivar<T>(&self, name: &str) -> &T

where T: Encode,

👎Deprecated: this is difficult to use correctly, use Ivar::load instead.

Use Ivar::load instead.

Safety

The object must have an instance variable with the given name, and it must be of type T.

See Ivar::load_ptr for details surrounding this.

pub fn downcast_ref<T>(&self) -> Option<&T>

where T: DowncastTarget,

Attempt to downcast the object to a class of type T.

This is the reference-variant. Use Retained::downcast if you want to convert a retained object to another type.

Mutable classes

Some classes have immutable and mutable variants, such as NSString and NSMutableString.

When some Objective-C API signature says it gives you an immutable class, it generally expects you to not mutate that, even though it may technically be mutable “under the hood”.

So using this method to convert a NSString to a NSMutableString, while not unsound, is generally frowned upon unless you created the string yourself, or the API explicitly documents the string to be mutable.

See Apple’s documentation on mutability and on isKindOfClass: for more details.

Generic classes

Objective-C generics are called “lightweight generics”, and that’s because they aren’t exposed in the runtime. This makes it impossible to safely downcast to generic collections, so this is disallowed by this method.

You can, however, safely downcast to generic collections where all the type-parameters are AnyObject.

Panics

This works internally by calling isKindOfClass:. That means that the object must have the instance method of that name, and an exception will be thrown (if CoreFoundation is linked) or the process will abort if that is not the case. In the vast majority of cases, you don’t need to worry about this, since both root objects NSObject and NSProxy implement this method.

Examples

Cast an NSString back and forth from NSObject.

use objc2::rc::Retained;
use objc2_foundation::{NSObject, NSString};

let obj: Retained<NSObject> = NSString::new().into_super();
let string = obj.downcast_ref::<NSString>().unwrap();
// Or with `downcast`, if we do not need the object afterwards
let string = obj.downcast::<NSString>().unwrap();

Try (and fail) to cast an NSObject to an NSString.

use objc2_foundation::{NSObject, NSString};

let obj = NSObject::new();
assert!(obj.downcast_ref::<NSString>().is_none());

Try to cast to an array of strings.

use objc2_foundation::{NSArray, NSObject, NSString};

let arr = NSArray::from_retained_slice(&[NSObject::new()]);
// This is invalid and doesn't type check.
let arr = arr.downcast_ref::<NSArray<NSString>>();

This fails to compile, since it would require enumerating over the array to ensure that each element is of the desired type, which is a performance pitfall.

Downcast when processing each element instead.

use objc2_foundation::{NSArray, NSObject, NSString};

let arr = NSArray::from_retained_slice(&[NSObject::new()]);

for elem in arr {
    if let Some(data) = elem.downcast_ref::<NSString>() {
        // handle `data`
    }
}

Trait Implementations

impl AsRef<AUParameter> for AUParameter

fn as_ref(&self) -> &Self

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<AUParameterNode> for AUParameter

fn as_ref(&self) -> &AUParameterNode

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<AnyObject> for AUParameter

fn as_ref(&self) -> &AnyObject

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<NSObject> for AUParameter

fn as_ref(&self) -> &NSObject

Converts this type into a shared reference of the (usually inferred) input type.

impl Borrow<AUParameterNode> for AUParameter

fn borrow(&self) -> &AUParameterNode

Immutably borrows from an owned value.

impl Borrow<AnyObject> for AUParameter

fn borrow(&self) -> &AnyObject

Immutably borrows from an owned value.

impl Borrow<NSObject> for AUParameter

fn borrow(&self) -> &NSObject

Immutably borrows from an owned value.

impl ClassType for AUParameter

const NAME: &'static str = "AUParameter"

The name of the Objective-C class that this type represents.

type Super = AUParameterNode

The superclass of this class.

type ThreadKind = <<AUParameter as ClassType>::Super as ClassType>::ThreadKind

Whether the type can be used from any thread, or from only the main thread.

fn class() -> &'static AnyClass

Get a reference to the Objective-C class that this type represents.

fn as_super(&self) -> &Self::Super

Get an immutable reference to the superclass.

impl Debug for AUParameter

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

Formats the value using the given formatter.

impl Deref for AUParameter

type Target = AUParameterNode

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl Hash for AUParameter

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Message for AUParameter

fn retain(&self) -> Retained<Self>

where Self: Sized,

Increment the reference count of the receiver.

impl NSObjectProtocol for AUParameter

fn isEqual(&self, other: Option<&AnyObject>) -> bool

where Self: Sized + Message,

Check whether the object is equal to an arbitrary other object.

fn hash(&self) -> usize

where Self: Sized + Message,

An integer that can be used as a table address in a hash table structure.

fn isKindOfClass(&self, cls: &AnyClass) -> bool

where Self: Sized + Message,

Check if the object is an instance of the class, or one of its subclasses.

fn is_kind_of<T>(&self) -> bool

where T: ClassType, Self: Sized + Message,

👎Deprecated: use isKindOfClass directly, or cast your objects with AnyObject::downcast_ref

Check if the object is an instance of the class type, or one of its subclasses.

fn isMemberOfClass(&self, cls: &AnyClass) -> bool

where Self: Sized + Message,

Check if the object is an instance of a specific class, without checking subclasses.

fn respondsToSelector(&self, aSelector: Sel) -> bool

where Self: Sized + Message,

Check whether the object implements or inherits a method with the given selector.

fn conformsToProtocol(&self, aProtocol: &AnyProtocol) -> bool

where Self: Sized + Message,

Check whether the object conforms to a given protocol.

fn description(&self) -> Retained<NSObject>

where Self: Sized + Message,

A textual representation of the object.

fn debugDescription(&self) -> Retained<NSObject>

where Self: Sized + Message,

A textual representation of the object to use when debugging.

fn isProxy(&self) -> bool

where Self: Sized + Message,

Check whether the receiver is a subclass of the NSProxy root class instead of the usual NSObject.

fn retainCount(&self) -> usize

where Self: Sized + Message,

The reference count of the object.

impl NSSecureCoding for AUParameter

unsafe fn supportsSecureCoding() -> bool

where Self: Sized + ClassType,

impl PartialEq for AUParameter

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl RefEncode for AUParameter

const ENCODING_REF: Encoding = <AUParameterNode as ::objc2::RefEncode>::ENCODING_REF

The Objective-C type-encoding for a reference of this type.

impl DowncastTarget for AUParameter

impl Eq for AUParameter

impl NSCoding for AUParameter