Struct VNVector

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

Available on crate feature VNGeometry only.

Expand description

VNVector is a two-dimensional vector represented its X and Y axis projections. Once created, VNVector objects are immutable.

Implementations§

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impl VNVector

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pub unsafe fn zeroVector() -> Retained<VNVector>

Returns a VNVector object with zero length. The theta for zeroVector is not defined (NaN).

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pub unsafe fn unitVectorForVector(vector: &VNVector) -> Retained<VNVector>

Returns a vector that is normalized by preserving direction, such as |v|, or vector length = 1.0.

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pub unsafe fn vectorByMultiplyingVector_byScalar( vector: &VNVector, scalar: c_double, ) -> Retained<VNVector>

Returns a vector that whose X and Y projections multiplied by a scalar value.

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pub unsafe fn vectorByAddingVector_toVector( v1: &VNVector, v2: &VNVector, ) -> Retained<VNVector>

Adds two vectors v1 and v2 and returns a resulting vector v, such as v = v1 + v2.

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pub unsafe fn vectorBySubtractingVector_fromVector( v1: &VNVector, v2: &VNVector, ) -> Retained<VNVector>

Substructs vector v1 from v2 and returns a resulting vector v, such as v = v2 - v1.

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pub unsafe fn dotProductOfVector_vector( v1: &VNVector, v2: &VNVector, ) -> c_double

Caclulates a dot product (aka ‘scalar product’ or ‘inner product’) of two vectors v1 and v2 and returns dot product value.

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

Initializes a vector in Cartesian Coordinate space, using its X and Y axis projections.

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pub unsafe fn initWithR_theta( this: Allocated<Self>, r: c_double, theta: c_double, ) -> Retained<Self>

Initializes a vector in polar coordinate space, using R and Theta (radians), where R is the length of the vector and Theta is the ange that the vector forms with the positive direction of X axis.

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pub unsafe fn initWithVectorHead_tail( this: Allocated<Self>, head: &VNPoint, tail: &VNPoint, ) -> Retained<Self>

Initializes a vector in Cartesian Coordinate space, using two VNPoints - the head and the tail of the vector.

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pub unsafe fn x(&self) -> c_double

Signed projection on X-axis, or X component of the vector. Sign determines direction the vector is facing in X direction.

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pub unsafe fn y(&self) -> c_double

Signed projection on Y-axis, or Y component of the vector. Sign determines direction the vector is facing in Y direction.

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pub unsafe fn r(&self) -> c_double

Radius, or absolute value, or length of the vector.

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pub unsafe fn theta(&self) -> c_double

Angle between the vector direction and positive direction of X axis.

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pub unsafe fn length(&self) -> c_double

Returns a length, or absolute value, of the vector.

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pub unsafe fn squaredLength(&self) -> c_double

Returns a length ^ 2 of a vector.

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impl VNVector

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 = 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`
    }
}