Struct IOSurface 

pub struct IOSurface(/* private fields */);

Hardware-accelerated surface for efficient frame delivery

IOSurface is Apple’s cross-process framebuffer type. It provides:

• Zero-copy sharing between processes
• Direct GPU texture creation via Metal
• Multi-planar format support (YCbCr, etc.)

Memory Access Safety

The surface must be locked before accessing pixel data. Use lock to get a RAII guard that ensures proper locking/unlocking.

Examples

use screencapturekit::cm::{IOSurface, IOSurfaceLockOptions};

fn access_surface(surface: &IOSurface) -> Result<(), i32> {
    // Lock for read-only access
    let guard = surface.lock(IOSurfaceLockOptions::READ_ONLY)?;
     
    // Access pixel data through the guard
    let data = guard.as_slice();
    println!("Surface has {} bytes", data.len());
     
    // Surface automatically unlocked when guard drops
    Ok(())
}

Implementations

impl IOSurface

pub fn create( width: usize, height: usize, pixel_format: u32, bytes_per_element: usize, ) -> Option<Self>

Create a new IOSurface with the given dimensions and pixel format

Arguments

• width - Width in pixels
• height - Height in pixels
• pixel_format - Pixel format as a FourCC code (e.g., 0x42475241 for ‘BGRA’)
• bytes_per_element - Bytes per pixel (e.g., 4 for BGRA)

Returns

Some(IOSurface) if creation succeeded, None otherwise.

Examples

use screencapturekit::cm::IOSurface;

// Create a 100x100 BGRA IOSurface
let surface = IOSurface::create(100, 100, 0x42475241, 4)
    .expect("Failed to create IOSurface");
assert_eq!(surface.width(), 100);
assert_eq!(surface.height(), 100);

pub fn create_with_properties( width: usize, height: usize, pixel_format: u32, bytes_per_element: usize, bytes_per_row: usize, alloc_size: usize, planes: Option<&[PlaneProperties]>, ) -> Option<Self>

Create an IOSurface with full properties including multi-planar support

This is the general API for creating IOSurfaces with any pixel format, including multi-planar formats like YCbCr 4:2:0.

Arguments

• width - Width in pixels
• height - Height in pixels
• pixel_format - Pixel format as FourCC (e.g., 0x42475241 for BGRA)
• bytes_per_element - Bytes per pixel element
• bytes_per_row - Bytes per row (should be 16-byte aligned for Metal)
• alloc_size - Total allocation size in bytes
• planes - Optional slice of plane info for multi-planar formats

Examples

use screencapturekit::cm::iosurface::PlaneProperties;
use screencapturekit::cm::IOSurface;

// Create a YCbCr 420v biplanar surface
let width = 1920usize;
let height = 1080usize;
let plane0_bpr = (width + 15) & !15;  // 16-byte aligned
let plane1_bpr = (width + 15) & !15;
let plane0_size = plane0_bpr * height;
let plane1_size = plane1_bpr * (height / 2);

let planes = [
    PlaneProperties {
        width,
        height,
        bytes_per_row: plane0_bpr,
        bytes_per_element: 1,
        offset: 0,
        size: plane0_size,
    },
    PlaneProperties {
        width: width / 2,
        height: height / 2,
        bytes_per_row: plane1_bpr,
        bytes_per_element: 2,
        offset: plane0_size,
        size: plane1_size,
    },
];

let surface = IOSurface::create_with_properties(
    width,
    height,
    0x34323076,  // '420v'
    1,
    plane0_bpr,
    plane0_size + plane1_size,
    Some(&planes),
);

pub fn from_raw(ptr: *mut c_void) -> Option<Self>

Create from raw pointer

pub unsafe fn from_ptr(ptr: *mut c_void) -> Self

Safety

The caller must ensure the pointer is a valid IOSurface pointer.

pub fn as_ptr(&self) -> *mut c_void

Get the raw pointer

pub fn width(&self) -> usize

Get the width of the surface in pixels

pub fn height(&self) -> usize

Get the height of the surface in pixels

pub fn bytes_per_row(&self) -> usize

Get the bytes per row of the surface

pub fn alloc_size(&self) -> usize

Get the total allocation size of the surface in bytes

pub fn data_size(&self) -> usize

Get the data size of the surface in bytes (alias for alloc_size)

This method provides API parity with CVPixelBuffer::data_size().

pub fn pixel_format(&self) -> u32

Get the pixel format of the surface (OSType/FourCC)

pub fn id(&self) -> u32

Get the unique IOSurfaceID for this surface

pub fn seed(&self) -> u32

Get the modification seed value

This value changes each time the surface is modified, useful for detecting whether the surface contents have changed.

pub fn plane_count(&self) -> usize

Get the number of planes in this surface

Multi-planar formats like YCbCr 420 have multiple planes:

• Plane 0: Y (luminance)
• Plane 1: CbCr (chrominance)

Single-plane formats like BGRA return 0.

pub fn width_of_plane(&self, plane_index: usize) -> usize

Get the width of a specific plane

For YCbCr 4:2:0 formats, plane 1 (CbCr) is half the width of plane 0 (Y).

pub fn height_of_plane(&self, plane_index: usize) -> usize

Get the height of a specific plane

For YCbCr 4:2:0 formats, plane 1 (CbCr) is half the height of plane 0 (Y).

pub fn bytes_per_row_of_plane(&self, plane_index: usize) -> usize

Get the bytes per row of a specific plane

pub fn bytes_per_element(&self) -> usize

Get the bytes per element of the surface

pub fn element_width(&self) -> usize

Get the element width of the surface

pub fn element_height(&self) -> usize

Get the element height of the surface

pub fn is_in_use(&self) -> bool

Check if the surface is currently in use

pub fn increment_use_count(&self)

Increment the use count of the surface

pub fn decrement_use_count(&self)

Decrement the use count of the surface

pub fn lock_raw(&self, options: IOSurfaceLockOptions) -> Result<u32, i32>

Lock the surface for CPU access (low-level API)

Prefer using lock for RAII-style access.

Arguments

• options - Lock options (e.g., IOSurfaceLockOptions::READ_ONLY)

Errors

Returns kern_return_t error code if the lock fails.

pub fn unlock_raw(&self, options: IOSurfaceLockOptions) -> Result<u32, i32>

Unlock the surface after CPU access (low-level API)

Arguments

• options - Must match the options used in the corresponding lock_raw() call

Errors

Returns kern_return_t error code if the unlock fails.

pub fn lock( &self, options: IOSurfaceLockOptions, ) -> Result<IOSurfaceLockGuard<'_>, i32>

Lock the surface and return a guard for RAII-style access

This is the recommended way to access surface memory. The guard ensures the surface is properly unlocked when it goes out of scope.

Arguments

• options - Lock options (e.g., IOSurfaceLockOptions::READ_ONLY)

Errors

Returns kern_return_t error code if the lock fails.

Examples

use screencapturekit::cm::{IOSurface, IOSurfaceLockOptions};

fn read_surface(surface: &IOSurface) -> Result<(), i32> {
    let guard = surface.lock(IOSurfaceLockOptions::READ_ONLY)?;
    let data = guard.as_slice();
    println!("Read {} bytes", data.len());
    Ok(())
}

pub fn lock_read_only(&self) -> Result<IOSurfaceLockGuard<'_>, i32>

Lock the surface for read-only access

This is a convenience method equivalent to lock(IOSurfaceLockOptions::READ_ONLY).

Errors

Returns kern_return_t error code if the lock fails.

pub fn lock_read_write(&self) -> Result<IOSurfaceLockGuard<'_>, i32>

Lock the surface for read-write access

This is a convenience method equivalent to lock(IOSurfaceLockOptions::NONE).

Errors

Returns kern_return_t error code if the lock fails.

impl IOSurface

pub fn info(&self) -> IOSurfaceInfo

Get detailed information about this IOSurface for Metal texture creation

pub fn is_ycbcr_biplanar(&self) -> bool

Check if this IOSurface uses a YCbCr biplanar format

impl IOSurface

pub fn texture_params(&self) -> Vec<TextureParams>

Get texture parameters for creating Metal textures from this IOSurface

Returns texture parameters for each plane needed to render this surface.

• Single-plane formats (BGRA, L10R): Returns 1 texture param
• YCbCr biplanar formats: Returns 2 texture params (Y and CbCr planes)

impl IOSurface

pub fn metal_textures<T, F>( &self, create_texture: F, ) -> Option<CapturedTextures<T>>

where F: Fn(&TextureParams, *const c_void) -> Option<T>,

Create Metal textures from this IOSurface using a closure

This is a zero-copy operation - the textures share memory with the IOSurface.

The closure receives TextureParams and the raw IOSurfaceRef pointer, and should return the created texture.

Example

use screencapturekit::cm::IOSurface;
use std::ffi::c_void;

fn example(surface: &IOSurface) {
    let textures = surface.metal_textures(|params, _iosurface_ptr| {
        // Create Metal texture using params.width, params.height, params.format
        // Return Some(texture) or None
        Some(()) // placeholder
    });

    if let Some(textures) = textures {
        if textures.is_ycbcr() {
            // Use YCbCr shader with plane0 (Y) and plane1 (CbCr)
        }
    }
}

Safety

The closure receives a raw IOSurfaceRef pointer. The pointer is valid for the duration of the closure call.

impl IOSurface

pub fn create_metal_textures( &self, device: &MetalDevice, ) -> Option<MetalCapturedTextures>

Create Metal textures from this IOSurface using the provided device

This is a zero-copy operation - the textures share memory with the IOSurface.

Example

use screencapturekit::metal::MetalDevice;
use screencapturekit::cm::IOSurface;

fn example(surface: &IOSurface) {
    let device = MetalDevice::system_default().expect("No Metal device");
    if let Some(textures) = surface.create_metal_textures(&device) {
        if textures.is_ycbcr() {
            // Use YCbCr shader with plane0 (Y) and plane1 (CbCr)
        }
    }
}

Trait Implementations

impl Clone for IOSurface

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for IOSurface

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

Formats the value using the given formatter.

impl Display for IOSurface

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

Formats the value using the given formatter.

impl Drop for IOSurface

fn drop(&mut self)

Executes the destructor for this type.

impl Hash for IOSurface

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 PartialEq for IOSurface

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 Eq for IOSurface

impl Send for IOSurface

impl Sync for IOSurface