Module metal 

Metal texture helpers for IOSurface

This module provides utilities for creating Metal textures from IOSurface with zero-copy GPU access. This is the most efficient way to use captured frames with Metal rendering.

Features

• Zero-copy texture creation from IOSurface
• Automatic pixel format detection and Metal format mapping
• Multi-plane support for YCbCr formats (420v, 420f)
• Native Metal device and texture types (no external crate needed)
• Embedded Metal shaders for common rendering scenarios

When to Use

Use this module when you need:

• Real-time rendering - Display captured frames in a Metal view
• GPU processing - Apply compute shaders to captured content
• Zero-copy performance - Avoid CPU-GPU memory transfers

For CPU-based processing, use CVPixelBuffer with lock guards instead.

Workflow

1. Get IOSurface from captured frame via CMSampleBuffer::image_buffer()
2. Create Metal textures with IOSurface::create_metal_textures()
3. Render using the built-in shaders or your own

Example

use screencapturekit::metal::MetalDevice;
use screencapturekit::cm::{CMSampleBuffer, IOSurface};

// Get the system default Metal device
let device = MetalDevice::system_default().expect("No Metal device");

// In your frame handler
fn handle_frame(sample: &CMSampleBuffer, device: &MetalDevice) {
    if let Some(pixel_buffer) = sample.image_buffer() {
        if let Some(surface) = pixel_buffer.io_surface() {
            // Create textures directly - no closures or factories needed
            if let Some(textures) = surface.create_metal_textures(device) {
                if textures.is_ycbcr() {
                    // Use YCbCr shader with plane0 (Y) and plane1 (CbCr)
                    println!("YCbCr texture: {}x{}",
                        textures.plane0.width(), textures.plane0.height());
                } else {
                    // Use single-plane shader (BGRA, l10r)
                    println!("Single-plane texture: {}x{}",
                        textures.plane0.width(), textures.plane0.height());
                }
            }
        }
    }
}

Built-in Shaders

The SHADER_SOURCE constant contains Metal shaders for common rendering scenarios:

Function	Description
vertex_fullscreen	Aspect-ratio-preserving fullscreen quad
fragment_textured	BGRA/L10R single-texture rendering
fragment_ycbcr	YCbCr biplanar (420v/420f) to RGB conversion
vertex_colored / fragment_colored	UI overlay rendering

Modules

pixel_format

Pixel format constants using FourCharCode

Structs

CapturedTextures

Result of creating Metal textures from an IOSurface

IOSurfaceInfo

Information about an IOSurface for Metal texture creation

MetalBuffer

A Metal buffer for vertex/uniform data

MetalCommandBuffer

A Metal command buffer

MetalCommandQueue

A Metal command queue

MetalDevice

A Metal device (GPU)

MetalDrawable

A drawable from a Metal layer

MetalFunction

A Metal shader function

MetalLayer

A CAMetalLayer for rendering to a window

MetalLibrary

A Metal shader library

MetalRenderCommandEncoder

A render command encoder

MetalRenderPassDescriptor

A render pass descriptor

MetalRenderPipelineDescriptor

A render pipeline descriptor

MetalRenderPipelineState

A compiled render pipeline state

MetalTexture

A Metal texture

MetalVertexDescriptor

A vertex descriptor for specifying vertex buffer layout

PlaneInfo

Information about a single plane within an IOSurface

ResourceOptions

Resource options for buffer creation

TextureParams

Metal texture descriptor parameters for creating textures from IOSurface

Uniforms

Uniforms structure for Metal shaders

Enums

MTLBlendFactor

Blend factor

MTLBlendOperation

Blend operation

MTLLoadAction

Load action for render pass attachments

MTLPixelFormat

Pixel format

MTLPrimitiveType

Primitive type for drawing

MTLStoreAction

Store action for render pass attachments

MTLVertexFormat

Vertex format for vertex attributes

MTLVertexStepFunction

Vertex step function

MetalPixelFormat

Metal pixel format enum matching MTLPixelFormat values

Constants

SHADER_SOURCE

Metal shader source for rendering captured frames

Functions

autoreleasepool

Execute a closure within an autorelease pool

setup_metal_view^⚠

Set up an NSView for Metal rendering

Type Aliases

MetalCapturedTextures

Result of creating Metal textures from an IOSurface