Struct VNGenerateOpticalFlowRequest

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

Available on crate features VNGenerateOpticalFlowRequest and VNRequest and VNTargetedImageRequest only.

VNGenerateOpticalFlowRequest will determine directional change vectors for each pixel in the targeted image to transform it into the image processed by the request handler, reporting this result with a single VNPixelBufferObservation.

Because this request works at the pixel level, both images must have the same dimensions in order for the request to be successfully performed. Setting a region of interest will isolate where the change determination is performed; however, the resultant observation will still be reported with a full resolution VNPixelBufferObservation.

Optical flow requests are very resource intensive, so it is recommended that only one request at a time be created and that the handler where the request was issued be released immediately after generating optical flows.

Example usage:

• (nullable VNPixelBufferObservation*) opticalFlowFromImage:(CVPixelBufferRef)fromImage toImage:(CVPixelBuffer)toImage error:(NSError**)error { VNImageRequestHandler* imageRequestHandler = [[VNImageRequestHandler alloc] initWithCVPixelBuffer:fromImage options: @ {}]; VNGenerateOpticalFlowRequest* request = [[VNGenerateOpticalFlowRequest alloc] initWithTargetedCVPixelBuffer:toImage options: @ {}]; if (![imageRequestHandler performRequests: @ [ request ] error:error]) { return nil; }

return [[request results] firstObject]; }

See also Apple’s documentation

Implementations

impl VNGenerateOpticalFlowRequest

pub unsafe fn computationAccuracy( &self, ) -> VNGenerateOpticalFlowRequestComputationAccuracy

The level of accuracy used to compute the optical flow. Default is VNGenerateOpticalFlowRequestComputationAccuracyMedium.

The computational time typically trends with the accuracy level. This parameter allows for selective tuning by the client application.

pub unsafe fn setComputationAccuracy( &self, computation_accuracy: VNGenerateOpticalFlowRequestComputationAccuracy, )

Setter for computationAccuracy.

pub unsafe fn outputPixelFormat(&self) -> u32

Pixel format type of the output buffer. Valid values are kCVPixelFormatType_TwoComponent32Float and kCVPixelFormatType_TwoComponent16Half. Default is kCVPixelFormatType_TwoComponent32Float.

pub unsafe fn setOutputPixelFormat(&self, output_pixel_format: u32)

Setter for outputPixelFormat.

pub unsafe fn keepNetworkOutput(&self) -> bool

Setting this to YES will keep the raw pixel buffer coming from the the ML network. The default is NO.

When set to YES, the outputPixelFormat is ignored. Setting this for revision 1 is a no-op as it is not ML-based.

pub unsafe fn setKeepNetworkOutput(&self, keep_network_output: bool)

Setter for keepNetworkOutput.

pub unsafe fn results( &self, ) -> Option<Retained<NSArray<VNPixelBufferObservation>>>

Available on crate feature VNObservation only.

VNPixelBufferObservation results.

impl VNGenerateOpticalFlowRequest

Methods declared on superclass VNTargetedImageRequest.

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

pub unsafe fn initWithCompletionHandler( this: Allocated<Self>, completion_handler: VNRequestCompletionHandler, ) -> Retained<Self>

Available on crate feature block2 only.

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

Available on crate features VNRequestHandler and objc2-core-video only.

Create a new request that targets an image in a pixel buffer.

Parameter pixelBuffer: The pixel buffer containing the targeted image.

Parameter options: A dictionary with options specifying auxiliary information for the image.

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

Available on crate features VNRequestHandler and block2 and objc2-core-video only.

Create a new request that targets an image in a pixel buffer.

Parameter pixelBuffer: The pixel buffer containing the targeted image.

Parameter options: A dictionary with options specifying auxiliary information for the image.

Parameter completionHandler: The block that is invoked when the request has been performed.

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

Available on crate features VNRequestHandler and objc2-core-graphics only.

Create a new request with a targeted CGImage.

Parameter cgImage: The CGImageRef of the targeted image.

Parameter options: A dictionary with options specifying auxiliary information for the image.

pub unsafe fn initWithTargetedCGImage_options_completionHandler( this: Allocated<Self>, cg_image: &CGImage, options: &NSDictionary<VNImageOption, AnyObject>, completion_handler: VNRequestCompletionHandler, ) -> Retained<Self>

Available on crate features VNRequestHandler and block2 and objc2-core-graphics only.

Create a new request with a targeted CGImage.

Parameter cgImage: The CGImageRef of the targeted image.

Parameter options: A dictionary with options specifying auxiliary information for the image.

Parameter completionHandler: The block that is invoked when the request has been performed.

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

Available on crate features VNRequestHandler and objc2-core-image only.

Create a new request with a targeted CIImage.

Parameter ciImage: The CIImage of the targeted image.

Parameter options: A dictionary with options specifying auxiliary information for the image.

pub unsafe fn initWithTargetedCIImage_options_completionHandler( this: Allocated<Self>, ci_image: &CIImage, options: &NSDictionary<VNImageOption, AnyObject>, completion_handler: VNRequestCompletionHandler, ) -> Retained<Self>

Available on crate features VNRequestHandler and block2 and objc2-core-image only.

Create a new request with a targeted CIImage.

Parameter ciImage: The CIImage of the targeted image.

Parameter options: A dictionary with options specifying auxiliary information for the image.

Parameter completionHandler: The block that is invoked when the request has been performed.

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

Available on crate feature VNRequestHandler only.

Create a new request with a targeted image URL.

Parameter imageURL: The URL of the targeted image.

Parameter options: A dictionary with options specifying auxiliary information for the image.

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

Available on crate features VNRequestHandler and block2 only.

Create a new request with a targeted image URL.

Parameter imageURL: The URL of the targeted image.

Parameter options: A dictionary with options specifying auxiliary information for the image.

Parameter completionHandler: The block that is invoked when the request has been performed.

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

Available on crate feature VNRequestHandler only.

Create a new request with a targeted image data.

Parameter imageData: The data of the targeted image.

Parameter options: A dictionary with options specifying auxiliary information for the image.

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

Available on crate features VNRequestHandler and block2 only.

Create a new request with a targeted image data.

Parameter imageData: The data of the targeted image.

Parameter options: A dictionary with options specifying auxiliary information for the image.

Parameter completionHandler: The block that is invoked when the request has been performed.

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

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

Create a new request with a targeted CMSampleBuffer.

Parameter sampleBuffer: The CMSampleBuffer containing the CVImageBuffer to be used by the request.

Parameter options: A dictionary with options specifying auxiliary information for the image.

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

Available on crate features VNRequestHandler and block2 and objc2-core-media only.

Create a new request with a targeted CMSampleBuffer.

Parameter sampleBuffer: The CMSampleBuffer containing the CVImageBuffer to be used by the request.

Parameter options: A dictionary with options specifying auxiliary information for the image.

Parameter completionHandler: The block that is invoked after the request has been performed.

impl VNGenerateOpticalFlowRequest

Methods declared on superclass NSObject.

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

Methods from Deref<Target = VNImageBasedRequest>

pub unsafe fn regionOfInterest(&self) -> CGRect

Available on crate feature objc2-core-foundation only.

The region of the image in which the request will be performed. The rectangle is normalized to the dimensions of the image being processed and has its origin specified relative to the image’s lower-left corner.

The default value for this property is { { 0, 0 }, { 1, 1 } }. Setting this property to a rectangle that is outside of the normalized coordinate space will be accepted but result in the request failing to be performed.

pub unsafe fn setRegionOfInterest(&self, region_of_interest: CGRect)

Available on crate feature objc2-core-foundation only.

Setter for regionOfInterest.

Methods from Deref<Target = VNRequest>

pub unsafe fn preferBackgroundProcessing(&self) -> bool

A hint used to minimize the resource burden of the request. Memory footprint, processing footprint and/or CPU/GPU contention will be reduced (depending on the request), at the potential cost of longer execution time. This can help, for example, with ensuring UI updates and rendering are not getting blocked by Vision processing.

pub unsafe fn setPreferBackgroundProcessing( &self, prefer_background_processing: bool, )

Setter for preferBackgroundProcessing.

pub unsafe fn usesCPUOnly(&self) -> bool

👎Deprecated

This property, if set to YES, signifies that the request should be performed exclusively on the CPU and not on the GPU. The default value is NO, which signifies that the request is free to leverage the GPU to accelerate any work the request may require.

pub unsafe fn setUsesCPUOnly(&self, uses_cpu_only: bool)

👎Deprecated

Setter for usesCPUOnly.

pub unsafe fn results(&self) -> Option<Retained<NSArray<VNObservation>>>

Available on crate feature VNObservation only.

The collection of VNObservations generated by the processing of the request.

The only valid time to access this property is after the request has been processed by a request handler. If the request failed, this property will be nil; otherwise, it will be an array of zero or more VNObservation subclasses specific to the VNRequest subclass.

pub unsafe fn completionHandler(&self) -> VNRequestCompletionHandler

Available on crate feature block2 only.

The completion handler block that will be invoked after the request has completed processing.

pub unsafe fn revision(&self) -> NSUInteger

The specific algorithm or implementation revision that is to be used to perform the request.

pub unsafe fn setRevision(&self, revision: NSUInteger)

Setter for revision.

pub unsafe fn cancel(&self)

Tries to abort the request as soon as possible. Results will be nil. The completionHandler (if present) will be called with an error of VNErrorRequestCancelled.

pub unsafe fn supportedComputeStageDevicesAndReturnError( &self, ) -> Result<Retained<NSDictionary<VNComputeStage, NSArray<ProtocolObject<dyn MLComputeDeviceProtocol>>>>, Retained<NSError>>

Available on crate features VNTypes and objc2-core-ml only.

Obtain the collection of compute device per stage that are supported by the request.

This method’s result is based on the current state of configuration of the target request at the time of the call.

Parameter error: The address of a variable that will be populated with the error that describes the failure. If the caller does not require this information, NULL can be passed.

Returns: A dictionary of per-stage supported compute devices, or nil if an error occurs.

pub unsafe fn computeDeviceForComputeStage( &self, compute_stage: &VNComputeStage, ) -> Option<Retained<ProtocolObject<dyn MLComputeDeviceProtocol>>>

Available on crate features VNTypes and objc2-core-ml only.

Determine what the currently configured compute device is for a specific compute stage.

Parameter computeStage: The compute stage to be introspected.

Returns: The currently assigned compute device, or nil if there is no explicit assignment.

pub unsafe fn setComputeDevice_forComputeStage( &self, compute_device: Option<&ProtocolObject<dyn MLComputeDeviceProtocol>>, compute_stage: &VNComputeStage, )

Available on crate features VNTypes and objc2-core-ml only.

Assign a specific compute device for a compute stage.

It is important to note that any compute device can be configured for a given compute stage. Only when the request is performed is the validity of the (compute device / compute stage) assignments checked. Valid compute devices for a request’s compute stages can be obtained via -supportedComputeStageDevicesAndReturnError:.

Parameter computeDevice: The compute device to assign to the compute stage. Passing nil for this parameter will remove any explicit compute device assignment, allowing Vision to select which device to use.

Parameter computeStage: The compute stage being configured.

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 VNGenerateOpticalFlowRequest

fn as_ref(&self) -> &AnyObject

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

impl AsRef<NSObject> for VNGenerateOpticalFlowRequest

fn as_ref(&self) -> &NSObject

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

impl AsRef<VNGenerateOpticalFlowRequest> for VNGenerateOpticalFlowRequest

fn as_ref(&self) -> &Self

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

impl AsRef<VNImageBasedRequest> for VNGenerateOpticalFlowRequest

fn as_ref(&self) -> &VNImageBasedRequest

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

impl AsRef<VNRequest> for VNGenerateOpticalFlowRequest

fn as_ref(&self) -> &VNRequest

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

impl AsRef<VNTargetedImageRequest> for VNGenerateOpticalFlowRequest

fn as_ref(&self) -> &VNTargetedImageRequest

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

impl Borrow<AnyObject> for VNGenerateOpticalFlowRequest

fn borrow(&self) -> &AnyObject

Immutably borrows from an owned value.

impl Borrow<NSObject> for VNGenerateOpticalFlowRequest

fn borrow(&self) -> &NSObject

Immutably borrows from an owned value.

impl Borrow<VNImageBasedRequest> for VNGenerateOpticalFlowRequest

fn borrow(&self) -> &VNImageBasedRequest

Immutably borrows from an owned value.

impl Borrow<VNRequest> for VNGenerateOpticalFlowRequest

fn borrow(&self) -> &VNRequest

Immutably borrows from an owned value.

impl Borrow<VNTargetedImageRequest> for VNGenerateOpticalFlowRequest

fn borrow(&self) -> &VNTargetedImageRequest

Immutably borrows from an owned value.

impl ClassType for VNGenerateOpticalFlowRequest

const NAME: &'static str = "VNGenerateOpticalFlowRequest"

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

type Super = VNTargetedImageRequest

The superclass of this class.

type ThreadKind = <<VNGenerateOpticalFlowRequest 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 CopyingHelper for VNGenerateOpticalFlowRequest

type Result = VNGenerateOpticalFlowRequest

The immutable counterpart of the type, or Self if the type has no immutable counterpart.

impl Debug for VNGenerateOpticalFlowRequest

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

Formats the value using the given formatter.

impl Deref for VNGenerateOpticalFlowRequest

type Target = VNTargetedImageRequest

The resulting type after dereferencing.

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

Dereferences the value.

impl Hash for VNGenerateOpticalFlowRequest

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 VNGenerateOpticalFlowRequest

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

where Self: Sized,

Increment the reference count of the receiver.

impl NSCopying for VNGenerateOpticalFlowRequest

fn copy(&self) -> Retained<Self::Result>

where Self: Sized + Message + CopyingHelper,

Returns a new instance that’s a copy of the receiver.

unsafe fn copyWithZone(&self, zone: *mut NSZone) -> Retained<Self::Result>

where Self: Sized + Message + CopyingHelper,

Returns a new instance that’s a copy of the receiver.

impl NSObjectProtocol for VNGenerateOpticalFlowRequest

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 VNGenerateOpticalFlowRequest

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 VNGenerateOpticalFlowRequest

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

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

impl DowncastTarget for VNGenerateOpticalFlowRequest

impl Eq for VNGenerateOpticalFlowRequest