Struct CMIOExtensionStreamCustomClockConfiguration

Source

pub struct CMIOExtensionStreamCustomClockConfiguration { /* private fields */ }

Available on crate feature CMIOExtensionProperties only.

Expand description

A CMIOExtensionStreamCustomClockProperties describes the parameters used to create a custom clock on the host side (as opposed to the stream using hosttime or a linked Core Audio clock.

Implementations§

Source §

pub unsafe fn customClockConfigurationWithClockName_sourceIdentifier_getTimeCallMinimumInterval_numberOfEventsForRateSmoothing_numberOfAveragesForRateSmoothing( clock_name: &NSString, source_identifier: &NSUUID, get_time_call_minimum_interval: CMTime, number_of_events_for_rate_smoothing: u32, number_of_averages_for_rate_smoothing: u32, ) -> Retained<Self>

Available on crate feature objc2-core-media only.

Return a custom clock configuration instance.

Parameter clockName: The name of the clock being specified.

Parameter sourceIdentifier: An unique identifier that is used to indicate the entity that is driving the clock. This value is used internally to determine if two custom clocks have the same hardware source, and thus determine whether or not they will drift relative to one another. This parameter is used in the following way: if a device supports multiple active streams that are internally clocked by a common source, then instead of sharing one clock between each stream, a clock per stream can be configured with the sourceIdentifier for each clock set to be the same value.

Parameter getTimeCallMinimumInterval: If the clock is queried for its current time more often than this interval, an interpolated value will be returned.

Parameter numberOfEventsForRateSmoothing: The number of events to use for rate smoothing; must be > 0.

Parameter numberOfAveragesForRateSmoothing: The number of averages used for rate smoothing; if 0, the default smoothing algorithm is used.

Returns: A CMIOExtensionStreamCustomClockConfiguration instance.

Source

pub unsafe fn initWithClockName_sourceIdentifier_getTimeCallMinimumInterval_numberOfEventsForRateSmoothing_numberOfAveragesForRateSmoothing( this: Allocated<Self>, clock_name: &NSString, source_identifier: &NSUUID, get_time_call_minimum_interval: CMTime, number_of_events_for_rate_smoothing: u32, number_of_averages_for_rate_smoothing: u32, ) -> Retained<Self>

Available on crate feature objc2-core-media only.

Initialize a custom clock configuration instance.

Parameter clockName: The name of the clock being specified.

Parameter sourceIdentifier: An unique identifier that is used to indicate the entity that is driving the clock. This value is used internally to determine if two custom clocks have the same hardware source, and thus determine whether or not they will drift relative to one another. This parameter is used in the following way: if a device supports multiple active streams that are internally clocked by a common source, then instead of sharing one clock between each stream, a clock per stream can be configured with the sourceIdentifier for each clock set to be the same value.

Parameter getTimeCallMinimumInterval: If the clock is queried for its current time more often than this interval, an interpolated value will be returned.

Parameter numberOfEventsForRateSmoothing: The number of events to use for rate smoothing; must be > 0.

Parameter numberOfAveragesForRateSmoothing: The number of averages used for rate smoothing; if 0, the default smoothing algorithm is used.

Returns: A CMIOExtensionStreamCustomClockConfiguration instance.

Source

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

The name of the clock.

Source

pub unsafe fn sourceIdentifier(&self) -> Retained<NSUUID>

The identifier of the entity driving the clock.

An unique identifier that is used to indicate the entity that is driving the clock. This value is used internally to determine if two custom clocks have the same hardware source, and thus determine whether or not they will drift relative to one another. This parameter is used in the following way: if a device supports multiple active streams that are internally clocked by a common source, then instead of sharing one clock between each stream, a clock per stream can be configured with the sourceIdentifier for each clock set to be the same value.

Source

pub unsafe fn getTimeCallMinimumInterval(&self) -> CMTime

Available on crate feature objc2-core-media only.

If the clock is queried for its current time more often than this interval, an interpolated value will be returned.

Source

pub unsafe fn numberOfEventsForRateSmoothing(&self) -> u32

The number of events to use for rate smoothing; will be > 0.

Source

pub unsafe fn numberOfAveragesForRateSmoothing(&self) -> u32

The number of averages used for rate smoothing; 0 indicates that the default smoothing algorithm is used.

Methods from Deref<Target = NSObject>§

Source

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

Handle messages the object doesn’t recognize.

See Apple’s documentation for details.

Methods from Deref<Target = AnyObject>§

Source

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());

Source

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.

Source

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`
    }
}