Struct AVAssetImageGenerator

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

Available on crate feature AVAssetImageGenerator only.

Expand description

Apple’s documentation

Implementations§

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pub unsafe fn asset(&self) -> Retained<AVAsset>

Available on crate feature AVAsset only.

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pub unsafe fn appliesPreferredTrackTransform(&self) -> bool

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pub unsafe fn setAppliesPreferredTrackTransform( &self, applies_preferred_track_transform: bool, )

Setter for appliesPreferredTrackTransform.

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pub unsafe fn maximumSize(&self) -> CGSize

Available on crate feature objc2-core-foundation only.

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pub unsafe fn setMaximumSize(&self, maximum_size: CGSize)

Available on crate feature objc2-core-foundation only.

Setter for maximumSize.

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pub unsafe fn apertureMode( &self, ) -> Option<Retained<AVAssetImageGeneratorApertureMode>>

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pub unsafe fn setApertureMode( &self, aperture_mode: Option<&AVAssetImageGeneratorApertureMode>, )

Setter for apertureMode.

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pub unsafe fn dynamicRangePolicy( &self, ) -> Retained<AVAssetImageGeneratorDynamicRangePolicy>

Configures the video dynamic range for the output CGImage

Default is AVAssetImageGeneratorDynamicRangePolicyForceSDR

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pub unsafe fn setDynamicRangePolicy( &self, dynamic_range_policy: &AVAssetImageGeneratorDynamicRangePolicy, )

Setter for dynamicRangePolicy.

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pub unsafe fn videoComposition(&self) -> Option<Retained<AVVideoComposition>>

Available on crate feature AVVideoComposition only.

Specifies the video composition to use when extracting images from assets with multiple video tracks.

If no videoComposition is specified, only the first enabled video track will be used. If a videoComposition is specified, the value of appliesPreferredTrackTransform is ignored. This property throws an exception if a video composition is set with any of the following property values:

“renderScale” is not equal to one
“renderSize” width or height is less than zero
“frameDuration” is invalid or less than or equal to zero
“sourceTrackIDForFrameTiming” is less than zero

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pub unsafe fn setVideoComposition( &self, video_composition: Option<&AVVideoComposition>, )

Available on crate feature AVVideoComposition only.

Setter for videoComposition.

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pub unsafe fn customVideoCompositor( &self, ) -> Option<Retained<ProtocolObject<dyn AVVideoCompositing>>>

Available on crate feature AVVideoCompositing only.

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pub unsafe fn requestedTimeToleranceBefore(&self) -> CMTime

Available on crate feature objc2-core-media only.

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pub unsafe fn setRequestedTimeToleranceBefore( &self, requested_time_tolerance_before: CMTime, )

Available on crate feature objc2-core-media only.

Setter for requestedTimeToleranceBefore.

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pub unsafe fn requestedTimeToleranceAfter(&self) -> CMTime

Available on crate feature objc2-core-media only.

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pub unsafe fn setRequestedTimeToleranceAfter( &self, requested_time_tolerance_after: CMTime, )

Available on crate feature objc2-core-media only.

Setter for requestedTimeToleranceAfter.

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pub unsafe fn assetImageGeneratorWithAsset(asset: &AVAsset) -> Retained<Self>

Available on crate feature AVAsset only.

Returns an instance of AVAssetImageGenerator for use with the specified asset.

Parameter asset: The asset from which images will be extracted.

Returns: An instance of AVAssetImageGenerator

This method may succeed even if the asset possesses no visual tracks at the time of initialization. Clients may wish to test whether an asset has any tracks with the visual characteristic via -[AVAsset tracksWithMediaCharacteristic:].

Note also that assets that belong to a mutable subclass of AVAsset, AVMutableComposition or AVMutableMovie, may gain visual tracks after initialization of an associated AVAssetImageGenerator.

However, the results of image generation are undefined if mutations of the asset occur while images are being generated.

AVAssetImageGenerator will use the default enabled video track(s) to generate images.

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pub unsafe fn initWithAsset( this: Allocated<Self>, asset: &AVAsset, ) -> Retained<Self>

Available on crate feature AVAsset only.

Initializes an instance of AVAssetImageGenerator for use with the specified asset.

Parameter asset: The asset from which images will be extracted.

Returns: An instance of AVAssetImageGenerator

This method may succeed even if the asset possesses no visual tracks at the time of initialization. Clients may wish to test whether an asset has any tracks with the visual characteristic via -[AVAsset tracksWithMediaCharacteristic:].

Note also that assets that belong to a mutable subclass of AVAsset, AVMutableComposition or AVMutableMovie, may gain visual tracks after initialization of an associated AVAssetImageGenerator.

However, the results of image generation are undefined if mutations of the asset occur while images are being generated.

AVAssetImageGenerator will use the default enabled video track(s) to generate images.

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pub unsafe fn generateCGImagesAsynchronouslyForTimes_completionHandler( &self, requested_times: &NSArray<NSValue>, handler: AVAssetImageGeneratorCompletionHandler, )

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

Returns a series of CGImageRefs for an asset at or near the specified times.

Parameter requestedTimes: An NSArray of NSValues, each containing a CMTime, specifying the asset times at which an image is requested.

Parameter handler: A block that will be called when an image request is complete.

Employs an efficient “batch mode” for getting images in time order. The client will receive exactly one handler callback for each requested time in requestedTimes. Changes to generator properties (snap behavior, maximum size, etc…) will not affect outstanding asynchronous image generation requests. The generated image is not retained. Clients should retain the image if they wish it to persist after the completion handler returns.

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pub unsafe fn generateCGImageAsynchronouslyForTime_completionHandler( &self, requested_time: CMTime, handler: &Block<dyn Fn(mut CGImage, CMTime, mut NSError)>, )

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

Returns a CGImageRef for an asset at or near the specified time.

Parameter requestedTime: A CMTime, specifying the asset time at which an image is requested.

Parameter handler: A block that will be called when the image request is complete.

The client will receive exactly one handler callback for requestedTime. Changes to generator properties (snap behavior, maximum size, etc…) will not affect outstanding asynchronous image generation requests. The generated image is not retained. Clients should retain the image if they wish it to persist after the completion handler returns. If image generation succeeds, the image parameter to the completion handler will be non-NULL and the error parameter will be nil. If image generation fails or was cancelled, the image parameter will be NULL and the error parameter will describe what went wrong. For cancelled images, the returned error will be AVErrorOperationCancelled.

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pub unsafe fn cancelAllCGImageGeneration(&self)

Cancels all outstanding image generation requests.

Calls the handler block with AVAssetImageGeneratorCancelled for each image time in every previous invocation of -generateCGImagesAsynchronouslyForTimes:completionHandler: for which images have not yet been supplied.

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.

§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`
    }
}