Struct CNFixedDetectionTrack

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pub struct CNFixedDetectionTrack { /* private fields */ }

Available on crate feature CNDetectionTrack only.

Expand description

A continuous detection track representing focus at a fixed disparity.

Implementations§

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impl CNFixedDetectionTrack

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pub unsafe fn initWithFocusDisparity( this: Allocated<Self>, focus_disparity: c_float, ) -> Retained<Self>

Create a detection track with fixed focus at the given disparity.

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pub unsafe fn initWithOriginalDetection( this: Allocated<Self>, original_detection: &CNDetection, ) -> Retained<Self>

Available on crate feature CNDetection only.

Create a detection track with fixed focus at the disparity of an existing detection.

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pub unsafe fn focusDisparity(&self) -> c_float

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pub unsafe fn originalDetection(&self) -> Option<Retained<CNDetection>>

Available on crate feature CNDetection only.

The original detection upon which this fixed detection track was based, if any.

This is the way to determine the time and rect from which fixed focus originated, if any. This detection is not part of the detection track and has a different detectionID or none.

Important: To get a detection from the fixed detection track, use detectionAtOrBeforeTime: instead, which will return a properly time-stamped detection.

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impl CNFixedDetectionTrack

Methods declared on superclass CNDetectionTrack.

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

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

Methods from Deref<Target = CNDetectionTrack>§

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pub unsafe fn detectionType(&self) -> CNDetectionType

Available on crate feature CNDetection only.

The type of subject detected by this detection track.

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pub unsafe fn detectionID(&self) -> CNDetectionID

Available on crate feature CNDetection only.

The detectionID of the subject detected during this track; unique within a cinematic script.

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pub unsafe fn detectionGroupID(&self) -> CNDetectionGroupID

Available on crate feature CNDetection only.

The detectionGroupID of the subject detected by the track.

The detectionGroupID can be used to associate related detections such as the face and torso of the same person.

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pub unsafe fn isUserCreated(&self) -> bool

Whether this detection track was created by the client.

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pub unsafe fn isDiscrete(&self) -> bool

Whether this detection track has discrete detections (otherwise continuous).

A discrete detection track will return detections only at the specific times a detection occurs. A continuous detection track will return a detection for any requested time and an empty array for time ranges.

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pub unsafe fn detectionAtOrBeforeTime( &self, time: CMTime, ) -> Option<Retained<CNDetection>>

Available on crate features CNDetection and objc2-core-media only.

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pub unsafe fn detectionNearestTime( &self, time: CMTime, ) -> Option<Retained<CNDetection>>

Available on crate features CNDetection and objc2-core-media only.

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pub unsafe fn detectionsInTimeRange( &self, time_range: CMTimeRange, ) -> Retained<NSArray<CNDetection>>

Available on crate features CNDetection and objc2-core-media only.

Gets the array of detections in the detection track within the given time range. Makes sense for discrete detection tracks only.

Methods from Deref<Target = NSObject>§

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

Handle messages the object doesn’t recognize.

See Apple’s documentation for details.

Methods from Deref<Target = AnyObject>§

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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());

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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.

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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`
    }
}