Struct AVCaptureScreenInput

Source

pub struct AVCaptureScreenInput { /* private fields */ }

Available on crate feature AVCaptureInput only.

Expand description

AVCaptureScreenInput is a concrete subclass of AVCaptureInput that provides an interface for capturing media from a screen or portion thereof.

Instances of AVCaptureScreenInput are input sources for AVCaptureSession that provide media data from one of the screens connected to the system, represented by CGDirectDisplayIDs.

Implementations§

Source §

impl AVCaptureScreenInput

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

Creates an AVCaptureScreenInput instance that provides media data from the main display.

This method creates an instance of AVCaptureScreenInput using the main display whose id is returned from CGMainDisplayID().

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

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pub unsafe fn initWithDisplayID( this: Allocated<Self>, display_id: CGDirectDisplayID, ) -> Option<Retained<Self>>

Available on crate feature objc2-core-graphics only.

Creates an AVCaptureScreenInput instance that provides media data from the given display.

Parameter displayID: The id of the display from which to capture video. CGDirectDisplayID is defined in <CoreGraphics /CGDirectDisplay.h>

Returns: An AVCaptureScreenInput instance that provides data from the given screen, or nil, if the screen could not be used for capture.

This method creates an instance of AVCaptureScreenInput that can be used to capture data from a display in an AVCaptureSession. This method validates the displayID. If the display cannot be used because it is not available on the system, for example, this method returns nil.

Source

pub unsafe fn minFrameDuration(&self) -> CMTime

Available on crate feature objc2-core-media only.

A property indicating the screen input’s minimum frame duration.

An AVCaptureScreenInput’s minFrameDuration is the reciprocal of its maximum frame rate. This property may be used to request a maximum frame rate at which the input produces video frames. The requested rate may not be achievable due to overall bandwidth, so actual frame rates may be lower.

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pub unsafe fn setMinFrameDuration(&self, min_frame_duration: CMTime)

Available on crate feature objc2-core-media only.

Setter for minFrameDuration.

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pub unsafe fn cropRect(&self) -> CGRect

Available on crate feature objc2-core-foundation only.

A property indicating the bounding rectangle of the screen area to be captured in points.

By default, AVCaptureScreenInput captures the entire area of the displayID with which it is associated. To limit the capture rectangle to a subsection of the screen, set the cropRect property, which defines a smaller section of the screen in the screen’s coordinate system. The origin (0,0) is the bottom-left corner of the screen.

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pub unsafe fn setCropRect(&self, crop_rect: CGRect)

Available on crate feature objc2-core-foundation only.

Setter for cropRect.

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pub unsafe fn scaleFactor(&self) -> CGFloat

Available on crate feature objc2-core-foundation only.

A property indicating the factor by which video buffers captured from the screen are to be scaled.

By default, AVCaptureScreenInput captures the video buffers from the display at a scale factor of 1.0 (no scaling). Set this property to scale the buffers by a given factor. For instance, a 320x240 capture area with a scaleFactor of 2.0f produces video buffers at 640x480.

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pub unsafe fn setScaleFactor(&self, scale_factor: CGFloat)

Available on crate feature objc2-core-foundation only.

Setter for scaleFactor.

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pub unsafe fn capturesMouseClicks(&self) -> bool

A property indicating whether mouse clicks should be highlighted in the captured output.

By default, AVCaptureScreenInput does not highlight mouse clicks in its captured output. If this property is set to YES, mouse clicks are highlighted (a circle is drawn around the mouse for the duration of the click) in the captured output.

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pub unsafe fn setCapturesMouseClicks(&self, captures_mouse_clicks: bool)

Setter for capturesMouseClicks.

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pub unsafe fn capturesCursor(&self) -> bool

A property indicating whether the cursor should be rendered to the captured output.

By default, AVCaptureScreenInput draws the cursor in its captured output. If this property is set to NO, the captured output contains only the windows on the screen. Cursor is omitted. Note that cursor position and mouse button state at the time of capture is preserved in CMSampleBuffers emitted from AVCaptureScreenInput. See the inline documentation for kCMIOSampleBufferAttachmentKey_MouseAndKeyboardModifiers in <CoreMediaIO /CMIOSampleBuffer.h>

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pub unsafe fn setCapturesCursor(&self, captures_cursor: bool)

Setter for capturesCursor.

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pub unsafe fn removesDuplicateFrames(&self) -> bool

👎Deprecated: No longer supported.

A property indicating whether duplicate frames should be removed by the input.

If this property is set to YES, AVCaptureScreenInput performs frame differencing and when it detects duplicate frames, it drops them. If set to NO, the captured output receives all frames from the input. Prior to 10.9 this value defaulted to YES. In 10.9 and later, it defaults to NO, as modern platforms support frame differencing in hardware-based encoders.

As of 10.10, this property has been deprecated and is ignored. Clients wishing to re-create this functionality can use an AVCaptureVideoDataOutput and compare frame contents in their own code. If they wish to write a movie file, they can then pass the unique frames to an AVAssetWriterInput.

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pub unsafe fn setRemovesDuplicateFrames(&self, removes_duplicate_frames: bool)

👎Deprecated: No longer supported.

Setter for removesDuplicateFrames.

Methods from Deref<Target = AVCaptureInput>§

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pub unsafe fn ports(&self) -> Retained<NSArray<AVCaptureInputPort>>

The ports owned by the receiver.

The value of this property is an array of AVCaptureInputPort objects, each exposing an interface to a single stream of media data provided by an input.

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.

§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`
    }
}