Struct VNContoursObservation

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

Available on crate feature VNObservation only.

Expand description

Apple’s documentation

Implementations§

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impl VNContoursObservation

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pub unsafe fn contourCount(&self) -> NSInteger

The total number of contours detected.

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pub unsafe fn contourAtIndex_error( &self, contour_index: NSInteger, ) -> Result<Retained<VNContour>, Retained<NSError>>

Available on crate feature VNGeometry only.

Returns the VNContour object at the specified index, irrespective of hierarchy.

Parameter contourIndex: The index of the contour to request. Valid values are in the range [0..contourCount-1].

Parameter error: The error returned if the index path is out of range.

Returns: The detected VNContour at the specified index without regard to hierarchy.

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pub unsafe fn topLevelContourCount(&self) -> NSInteger

The total number of top-level contours detected.

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pub unsafe fn topLevelContours(&self) -> Retained<NSArray<VNContour>>

Available on crate feature VNGeometry only.

An array of the top level contours (i.e. contours that are not enclosed inside another contour),.

This array constitutes the top of the contour hierarchy. Each contour object can be further iterated to determine its children.

See: VNContour for more information.

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pub unsafe fn contourAtIndexPath_error( &self, index_path: &NSIndexPath, ) -> Result<Retained<VNContour>, Retained<NSError>>

Available on crate feature VNGeometry only.

Returns the VNContour object at the specified index path.

Use the indexPath property from a VNContour instance to pass to this method.

Parameter indexPath: The index path is the heirarchical path to the contour.

Parameter error: The error returned if the index path is out of range.

Returns: The VNContour object at the specified index path.

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pub unsafe fn normalizedPath(&self) -> Retained<CGPath>

Available on crate feature objc2-core-graphics only.

Obtain all of the contours represented as a CGPath in normalized coordinates.

The path is owned by the observation and therefore will be alive as long as the the observation is alive.

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impl VNContoursObservation

Methods declared on superclass NSObject.

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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 = VNObservation>§

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

The unique identifier assigned to an observation.

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pub unsafe fn confidence(&self) -> VNConfidence

Available on crate feature VNTypes only.

The level of confidence normalized to [0, 1] where 1 is most confident. The only exception is results coming from VNCoreMLRequest, where confidence values are forwarded as is from relevant CoreML models

Confidence can always be returned as 1.0 if confidence is not supported or has no meaning

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pub unsafe fn timeRange(&self) -> CMTimeRange

Available on crate feature objc2-core-media only.

The duration of the observation reporting when first detected and how long it is valid.

The duration of the observation when used with a sequence of buffers. If a request does not support a timeRange or the timeRange is not known, the start time and duration will be set to 0.

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`
    }
}