Struct VNRecognizedPoint

Source

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

Available on crate features VNDetectedPoint and VNGeometry only.

Expand description

An extension of VNDetectedPoint that associates an identifier to the point.

It should be noted that VNRecognizedPoint is not intended as an overall replacement of CGPoint, NSPoint or vec2, but is used by observations that recognize labeled points of interest.

Implementations§

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impl VNRecognizedPoint

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

Available on crate feature VNTypes only.

The is the identifier that provides context as to the kind of point that was recognized.

The string is defined by the model that recognized the point. Usually these are technical labels that are not localized and not meant to be used directly to be presented to an end user in the UI.

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impl VNRecognizedPoint

Methods declared on superclass VNDetectedPoint.

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

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

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pub unsafe fn initWithX_y( this: Allocated<Self>, x: c_double, y: c_double, ) -> Retained<Self>

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pub unsafe fn initWithLocation( this: Allocated<Self>, location: CGPoint, ) -> Retained<Self>

Available on crate feature objc2-core-foundation only.

Methods from Deref<Target = VNDetectedPoint>§

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pub unsafe fn confidence(&self) -> VNConfidence

Available on crate feature VNTypes only.

The confidence in the accuracy of the location, in the range of [0.0, 1.0].

Methods from Deref<Target = VNPoint>§

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pub unsafe fn distanceToPoint(&self, point: &VNPoint) -> c_double

Returns the Euclidean distance to another point.

Parameter point: The destination point.

Returns: the Euclidean distance between the target and specified points.

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pub unsafe fn location(&self) -> CGPoint

Available on crate feature objc2-core-foundation only.

Returns the X and Y coordinates of the point, as CGPoint type, with respect to the origin of the coordinate system the point is defined in.

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pub unsafe fn x(&self) -> c_double

Returns the X coordinate of the point with respect to the origin of the coordinate system the point is defined in.

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pub unsafe fn y(&self) -> c_double

Returns the Y coordinate of the point with respect to the origin of the coordinate system the point is defined in.

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.

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`
    }
}