Struct VNImageRequestHandler

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

Available on crate feature VNRequestHandler only.

Performs requests on a single image.

The VNImageRequestHandler is created with an image that is used to be used for the requests a client might want to schedule. The VNImageRequestHandler retains, but never modifies, the image source for its entire lifetime. The client also must not modify the content of the image source once the VNImageRequestHandler is created otherwise the results are undefined. The VNImageRequestHandler can choose to also cache intermediate representation of the image or other request-specific information for the purposes of runtime performance.

See also Apple’s documentation

Implementations

impl VNImageRequestHandler

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

pub unsafe fn initWithCVPixelBuffer_options( this: Allocated<Self>, pixel_buffer: &CVPixelBuffer, options: &NSDictionary<VNImageOption, AnyObject>, ) -> Retained<Self>

Available on crate feature objc2-core-video only.

initWithCVPixelBuffer:options creates a VNImageRequestHandler to be used for performing requests against the image passed in as buffer.

Parameter pixelBuffer: A CVPixelBuffer containing the image to be used for performing the requests. The content of the buffer cannot be modified for the lifetime of the VNImageRequestHandler.

Parameter options: A dictionary with options specifying auxiliary information for the buffer/image like VNImageOptionCameraIntrinsics

pub unsafe fn initWithCGImage_options( this: Allocated<Self>, image: &CGImage, options: &NSDictionary<VNImageOption, AnyObject>, ) -> Retained<Self>

Available on crate feature objc2-core-graphics only.

initWithCGImage:options creates a VNImageRequestHandler to be used for performing requests against the image passed in as a CGImageRef.

Parameter image: A CGImageRef containing the image to be used for performing the requests. The content of the image cannot be modified.

Parameter options: A dictionary with options specifying auxiliary information for the buffer/image like VNImageOptionCameraIntrinsics

pub unsafe fn initWithCIImage_options( this: Allocated<Self>, image: &CIImage, options: &NSDictionary<VNImageOption, AnyObject>, ) -> Retained<Self>

Available on crate feature objc2-core-image only.

initWithCIImage:options creates a VNImageRequestHandler to be used for performing requests against the image passed in as a CIImage.

Parameter image: A CIImage containing the image to be used for performing the requests. The content of the image cannot be modified.

Parameter options: A dictionary with options specifying auxiliary information for the buffer/image like VNImageOptionCameraIntrinsics

Note: : Request results may not be accurate in simulator due to CI’s inability to render certain pixel formats in the simulator. The orientation of the original image should be applied for instance by using imageByApplyingOrientation or use the initWithCIImage:options:orientation API.

pub unsafe fn initWithURL_options( this: Allocated<Self>, image_url: &NSURL, options: &NSDictionary<VNImageOption, AnyObject>, ) -> Retained<Self>

initWithURL:options creates a VNImageRequestHandler to be used for performing requests against an image specified by it’s URL

Parameter imageURL: A URL pointing at an image to be used for performing the requests. The image has to be in a format that is supported by ImageIO. The content of the image cannot be modified.

Parameter options: A dictionary with options specifying auxiliary information for the buffer/image like VNImageOptionCameraIntrinsics

Note: : Request results may not be accurate in simulator due to CI’s inability to render certain pixel formats in the simulator

pub fn initWithData_options( this: Allocated<Self>, image_data: &NSData, options: &NSDictionary<VNImageOption, AnyObject>, ) -> Retained<Self>

initWithData:options creates a VNImageRequestHandler to be used for performing requests against an image contained in an NSData object.

Parameter imageData: An NSData object containing the content of the image to be used for performing the requests. See CIImage imageWithData for supported format. The content of the image cannot be modified.

Parameter options: A dictionary with options specifying auxiliary information for the buffer/image like VNImageOptionCameraIntrinsics

Note: : Request results may not be accurate in simulator due to CI’s inability to render certain pixel formats in the simulator

pub unsafe fn initWithCMSampleBuffer_options( this: Allocated<Self>, sample_buffer: &CMSampleBuffer, options: &NSDictionary<VNImageOption, AnyObject>, ) -> Retained<Self>

Available on crate feature objc2-core-media only.

Creates a VNImageRequestHandler to be used for performing requests against the image buffer contained in the CMSampleBufferRef

Parameter sampleBuffer: A CMSampleBuffer containing the imageBuffer that will be used for performing the requests. Not all types of sample buffers are supported. They need to contain a CVImageBuffer, be valid and ready.

Parameter options: A dictionary with options specifying auxiliary information for the buffer/image like VNImageOptionCameraIntrinsics

Note: CMSampleBuffers can contain metadata like camera intrinsics that will be used by algorithms supporting it unless overwritten by the options.

pub fn performRequests_error( &self, requests: &NSArray<VNRequest>, ) -> Result<(), Retained<NSError>>

Available on crate feature VNRequest only.

performRequests schedules one or more VNRequests to be performed. The function returns once all requests have been finished.

The results of the VNRequests as well any possible errors of the individual requests are reported in the VNRequests results and error properties.

Parameter requests: An NSArray of VNRequests that are to be performed.

Parameter error: Returns an error that happened during scheduling of the requests. Check individual requests results and errors for their respective success and failures. This parameter is optional.

Returns: Returns true if all requests were scheduled and performed. Check individual requests results and errors for their respective success and failures.

impl VNImageRequestHandler

Methods declared on superclass NSObject.

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

Methods from Deref<Target = NSObject>

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

Handle messages the object doesn’t recognize.

See Apple’s documentation for details.

Methods from Deref<Target = AnyObject>

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());

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.

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`
    }
}

Trait Implementations

impl AsRef<AnyObject> for VNImageRequestHandler

fn as_ref(&self) -> &AnyObject

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<NSObject> for VNImageRequestHandler

fn as_ref(&self) -> &NSObject

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<VNImageRequestHandler> for VNImageRequestHandler

fn as_ref(&self) -> &Self

Converts this type into a shared reference of the (usually inferred) input type.

impl Borrow<AnyObject> for VNImageRequestHandler

fn borrow(&self) -> &AnyObject

Immutably borrows from an owned value.

impl Borrow<NSObject> for VNImageRequestHandler

fn borrow(&self) -> &NSObject

Immutably borrows from an owned value.

impl ClassType for VNImageRequestHandler

const NAME: &'static str = "VNImageRequestHandler"

The name of the Objective-C class that this type represents.

type Super = NSObject

The superclass of this class.

type ThreadKind = <<VNImageRequestHandler as ClassType>::Super as ClassType>::ThreadKind

Whether the type can be used from any thread, or from only the main thread.

fn class() -> &'static AnyClass

Get a reference to the Objective-C class that this type represents.

fn as_super(&self) -> &Self::Super

Get an immutable reference to the superclass.

impl Debug for VNImageRequestHandler

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Deref for VNImageRequestHandler

type Target = NSObject

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl Hash for VNImageRequestHandler

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Message for VNImageRequestHandler

fn retain(&self) -> Retained<Self>

where Self: Sized,

Increment the reference count of the receiver.

impl NSObjectProtocol for VNImageRequestHandler

fn isEqual(&self, other: Option<&AnyObject>) -> bool

where Self: Sized + Message,

Check whether the object is equal to an arbitrary other object.

fn hash(&self) -> usize

where Self: Sized + Message,

An integer that can be used as a table address in a hash table structure.

fn isKindOfClass(&self, cls: &AnyClass) -> bool

where Self: Sized + Message,

Check if the object is an instance of the class, or one of its subclasses.

fn is_kind_of<T>(&self) -> bool

where T: ClassType, Self: Sized + Message,

👎Deprecated: use isKindOfClass directly, or cast your objects with AnyObject::downcast_ref

Check if the object is an instance of the class type, or one of its subclasses.

fn isMemberOfClass(&self, cls: &AnyClass) -> bool

where Self: Sized + Message,

Check if the object is an instance of a specific class, without checking subclasses.

fn respondsToSelector(&self, aSelector: Sel) -> bool

where Self: Sized + Message,

Check whether the object implements or inherits a method with the given selector.

fn conformsToProtocol(&self, aProtocol: &AnyProtocol) -> bool

where Self: Sized + Message,

Check whether the object conforms to a given protocol.

fn description(&self) -> Retained<NSObject>

where Self: Sized + Message,

A textual representation of the object.

fn debugDescription(&self) -> Retained<NSObject>

where Self: Sized + Message,

A textual representation of the object to use when debugging.

fn isProxy(&self) -> bool

where Self: Sized + Message,

Check whether the receiver is a subclass of the NSProxy root class instead of the usual NSObject.

fn retainCount(&self) -> usize

where Self: Sized + Message,

The reference count of the object.

impl PartialEq for VNImageRequestHandler

fn eq(&self, other: &Self) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl RefEncode for VNImageRequestHandler

const ENCODING_REF: Encoding = <NSObject as ::objc2::RefEncode>::ENCODING_REF

The Objective-C type-encoding for a reference of this type.

impl DowncastTarget for VNImageRequestHandler

impl Eq for VNImageRequestHandler