Struct VTFrameProcessor 

pub struct VTFrameProcessor { /* private fields */ }

Available on crate features VTFrameProcessor and objc2 only.

Provides a unified interface you can use to apply video effects to frames.

The VTFrameProcessor gives access to a set of powerful video processing implementation suitable for different use cases. A configuration object (conforming to the VTFrameProcessorConfiguration protocol) passes initialization and configuration parameters for the processor. A Parameter object (conforming to the VTFrameProcessorParameters protocol) provides the parameters for each individual processing operation. A Configuration object and a Parameter object define each processor implementation. These Configuration and Parameters objects for each implementation are defined in a processor-specific header file.

Use an instance of this class to apply configured video effects either directly to pixel buffers or as a part of Metal pipeline. The video effect must be specified as a VTFrameProcessorConfiguration instance at session startup. Once a session is started, you need to call one of the process methods for each input frame. After all input frames have been provided, session must be ended for the system to finish all pending processing.

After you call the process function, you must not modify input and output buffers (including attachments) before the function returns or the system receives the callback, in the case of asynchronous processing.

See also Apple’s documentation

Implementations

impl VTFrameProcessor

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

Create a new instance of the frame processor.

pub unsafe fn startSessionWithConfiguration_error( &self, configuration: &ProtocolObject<dyn VTFrameProcessorConfiguration>, ) -> Result<(), Retained<NSError>>

Available on crate features VTFrameProcessorConfiguration and objc2-foundation only.

Starts a new session and configures the processor pipeline for an effect.

• Parameters:
• configuration: The system uses this parameter to create an effect pipeline for processing frames. This object must conform to the VTFrameProcessorConfiguration interface.
• error: Contains error information if any. You may specify NULL for this parameter if you do not want the error information.

pub unsafe fn processWithParameters_error( &self, parameters: &ProtocolObject<dyn VTFrameProcessorParameters>, ) -> Result<(), Retained<NSError>>

Available on crate features VTFrameProcessorParameters and objc2-foundation only.

Synchronously performs the processor effects.

Use the respective VTFrameProcessorParameters to pass frame level settings and frame level input/output parameters for the effect that you configured this session for by calling startSessionWithConfiguration:error.

• Parameters:
• parameters: A VTFrameProcessorParameters based object to specify additional frame based parameters to use during processing. It needs to match the configuration type used during start session.
• error: Contains error information if any. You may specify NULL for this parameter if you do not want the error information.

pub unsafe fn processWithParameters_completionHandler( &self, parameters: &ProtocolObject<dyn VTFrameProcessorParameters>, completion_handler: &DynBlock<dyn Fn(NonNull<ProtocolObject<dyn VTFrameProcessorParameters>>, *mut NSError)>, )

Available on crate features VTFrameProcessorParameters and block2 and objc2-foundation only.

Asynchronously performs the processor effects.

• Parameters:
• parameters: A VTFrameProcessorParameters based object to specify additional frame based parameters to use during processing. It needs to match the configuration type used during start session.
• completionHandler: This completion handler is called when frame processing is completed. The completion handler receives the same parameters object that you provided to the original call, as well as an NSError which contains an error code if processing was not successful.

pub unsafe fn processWithParameters_frameOutputHandler( &self, parameters: &ProtocolObject<dyn VTFrameProcessorParameters>, frame_output_handler: &DynBlock<dyn Fn(NonNull<ProtocolObject<dyn VTFrameProcessorParameters>>, CMTime, Bool, *mut NSError)>, )

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

Asynchronously performs the processor effects and outputs each frame separately.

Use with frame processor configurations which allow multiple output frames from a single processing call, such as frame rate conversion processor cases when you need access to output frames as they become available, rather than waiting for all output frames to be complete.

This interface is suitable for low-latency scenarios when a call would generate multiple output frames, but waiting for all frames to be generated before beginning to use the frames is not ideal. Because the processor may use the output frames as references for frames still being generated, the output frames are strictly read-only. If you want to modify the frames, you must create a copy first.

• Parameters:
• parameters: A VTFrameProcessorParameters based object to specify additional frame based parameters to use during processing. It needs to match the configuration type used during start session.
• frameOutputHandler: This frame output handler is called once for each destination frame in the provided parameters if no errors are encountered. The output handler receives the same parameters object that you provided to the original call, a flag indicating if this is the final output to be called for this processing request, and the presentation timestamp associated with the VTFrameProcessorFrame that it is being called for. The NSError parameter contains an error code if processing was not successful.

pub unsafe fn processWithCommandBuffer_parameters( &self, command_buffer: &ProtocolObject<dyn MTLCommandBuffer>, parameters: &ProtocolObject<dyn VTFrameProcessorParameters>, )

Available on crate features VTFrameProcessorParameters and objc2-metal only.

Performs effects in a Metal command buffer.

This function allows you to add the effect to an existing Metal command buffer. The clients that have an existing Metal pipeline and want to add this effect to it can use this function.

Note: this function waits until all previously inserted tasks in the command buffer finish before running. Tasks inserted after the processWithCommandBuffer returns are run by the system after the effect is applied. Processing does not happen until the commandBuffer is executed.

• Parameters:
• commandBuffer: An existing Metal command buffer where the frame processing is inserted.
• parameters: A VTFrameProcessorParameters based object to specify additional frame based parameters to use during processing. It needs to match the configuration type used during start session.

pub unsafe fn endSession(&self)

Performs all necessary tasks to end the session.

After this call completes, you can process no new frames unless you call startSessionWithConfiguration again.

impl VTFrameProcessor

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 VTFrameProcessor

fn as_ref(&self) -> &AnyObject

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

impl AsRef<NSObject> for VTFrameProcessor

fn as_ref(&self) -> &NSObject

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

impl AsRef<VTFrameProcessor> for VTFrameProcessor

fn as_ref(&self) -> &Self

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

impl Borrow<AnyObject> for VTFrameProcessor

fn borrow(&self) -> &AnyObject

Immutably borrows from an owned value.

impl Borrow<NSObject> for VTFrameProcessor

fn borrow(&self) -> &NSObject

Immutably borrows from an owned value.

impl ClassType for VTFrameProcessor

const NAME: &'static str = "VTFrameProcessor"

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

type Super = NSObject

The superclass of this class.

type ThreadKind = <<VTFrameProcessor 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 VTFrameProcessor

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

Formats the value using the given formatter.

impl Deref for VTFrameProcessor

type Target = NSObject

The resulting type after dereferencing.

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

Dereferences the value.

impl Hash for VTFrameProcessor

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 VTFrameProcessor

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

where Self: Sized,

Increment the reference count of the receiver.

impl NSObjectProtocol for VTFrameProcessor

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 VTFrameProcessor

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 VTFrameProcessor

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

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

impl DowncastTarget for VTFrameProcessor

impl Eq for VTFrameProcessor