Struct AVCaptionRegion

Source

pub struct AVCaptionRegion { /* private fields */ }

Available on crate feature AVCaption only.

Expand description

An instance of AVCaptionRegion represents a region where a caption is placed.

Currently, there is just four predefined region instances. The interface doesn’t support configuration of region settings.

Implementations§

Source §

impl AVCaptionRegion

Source

pub unsafe fn appleITTTopRegion() -> Retained<AVCaptionRegion>

The top region for iTT format

This region can be used in iTT format and it occupies the top 15% of the display area. The region uses LRTB, a line progresses left to right and the block extends from top to bottom. Each line is stacked with top justified.

Source

pub unsafe fn appleITTBottomRegion() -> Retained<AVCaptionRegion>

The bottom region for iTT format

This region can be used in iTT format and it occupies the bottom 15% of the display area. The region uses LRTB, a line progresses left to right and the block extends from top to bottom. Each line is stacked with bottom justified.

Source

pub unsafe fn appleITTLeftRegion() -> Retained<AVCaptionRegion>

The left region for iTT format

This region can be used in iTT format and it occupies the left 15% of the display area. The region uses TBRL, a line progresses top to bottom and the block extends from right to left. Each line is stacked with right justified.

Source

pub unsafe fn appleITTRightRegion() -> Retained<AVCaptionRegion>

The right region for iTT format

This region can be used in iTT format and it occupies the right 15% of the display area. The region uses TBRL, a line progresses top to bottom and the block extends from right to left. Each line is stacked with right justified.

Source

pub unsafe fn subRipTextBottomRegion() -> Retained<AVCaptionRegion>

The bottom region for SubRip Text (SRT) format

This region can be used in SRT format and it occupies the entire video display area. The region uses LRTB, a line progresses left to right and the block extends from top to bottom. Each line is stacked with bottom justified.

Source

pub unsafe fn identifier(&self) -> Option<Retained<NSString>>

Identifier for the region

When regionIdentifier is nil, two regions with the same position and endPosition are considered to be same, that is captions referring these regions belong to the same region when serialized to a format like TTML. In addition, the AVCaptionRegion cannot be mutably copied.

When regionIdentifier is not nil, two regions are same if and only if the region identifier is equal. It is a client’s responsibility to ensure these AVCaptionRegion objects have the same properties.

Source

pub unsafe fn origin(&self) -> AVCaptionPoint

Available on crate feature objc2-core-foundation only.

The position of the top-left of the region, potentially with unspecified fields.

It returns an AVCaptionPoint potentially with unspecified x and/or y fields. Unspecified dimensions indicate the region doesn’t have positioning information for that dimension.

Source

pub unsafe fn size(&self) -> AVCaptionSize

Available on crate feature objc2-core-foundation only.

The width and height of the region, potentally with unspecified fields.

It returns an AVCaptionSize potentially with unspecified width and/or height. CEA608 closed captions support limits the size.height property’s value to 1 cell except when the AVCaptionRegionScroll is AVCaptionRegionScrollRollUp. If the AVCaptionRegionScroll is AVCaptionRegionScrollRollUp, the size.height property’s value must be 2, 3 or 4 cells. It returns an AVCaptionSize with unspecifed width and height when the region doesn’t have width or height information.

Source

pub unsafe fn scroll(&self) -> AVCaptionRegionScroll

Scroll mode for the region

See AVCaptionRegionScrollXXX enum for possible values.

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pub unsafe fn displayAlignment(&self) -> AVCaptionRegionDisplayAlignment

Alignment of lines for the region

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pub unsafe fn writingMode(&self) -> AVCaptionRegionWritingMode

The block and inline progression direction of the region.

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pub unsafe fn encodeWithCoder(&self, encoder: &NSCoder)

NSCoding protocol method override

This method throws an exception if the caption region’s size has different units for width and height, or if the units are unrecognizeable.

§Safety

encoder possibly has further requirements.

Source

pub unsafe fn isEqual(&self, object: &AnyObject) -> bool

NSObject protocol method override

This method throws an exception if the caption region’s size has different units for width and height, or if the units are unrecognizeable.

§Safety

object should be of the correct type.

Source

pub unsafe fn mutableCopyWithZone( &self, zone: *mut NSZone, ) -> Retained<AnyObject>

NSMutableCopying protocol method override

This method throws an exception if the caption region contains an identifier.

§Safety

zone must be a valid pointer or null.

Source §

impl AVCaptionRegion

Methods declared on superclass NSObject.

Source

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

Source

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

Methods from Deref<Target = NSObject>§

Source

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());

Source

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.

Source

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`
    }
}