obs-studio/libobs-metal/MetalStageBuffer.swift

/******************************************************************************
 Copyright (C) 2024 by Patrick Heyer <[email protected]>

 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation, either version 2 of the License, or
 (at your option) any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 ******************************************************************************/

import Foundation
import Metal

class MetalStageBuffer {
    let device: MetalDevice
    let buffer: MTLBuffer
    let format: MTLPixelFormat
    let width: Int
    let height: Int

    init?(device: MetalDevice, width: Int, height: Int, format: MTLPixelFormat) {
        self.device = device
        self.width = width
        self.height = height
        self.format = format

        guard let bytesPerPixel = format.bytesPerPixel,
            let buffer = device.device.makeBuffer(
                length: width * height * bytesPerPixel,
                options: .storageModeShared
            )
        else {
            return nil
        }

        self.buffer = buffer
    }

    /// Gets an opaque pointer for the ``MetalStageBuffer`` instance and increases its reference count by one
    /// - Returns: `OpaquePointer` to class instance
    ///
    /// > Note: Use this method when the instance is to be shared via an `OpaquePointer` and needs to be retained. Any
    ///  opaque pointer shared this way needs to be converted into a retained reference again to ensure automatic
    /// deinitialization by the Swift runtime.
    func getRetained() -> OpaquePointer {
        let retained = Unmanaged.passRetained(self).toOpaque()

        return OpaquePointer(retained)
    }

    /// Gets an opaque pointer for the ``MetalStageBuffer`` instance without increasing its reference count
    /// - Returns: `OpaquePointer` to class instance
    func getUnretained() -> OpaquePointer {
        let unretained = Unmanaged.passUnretained(self).toOpaque()

        return OpaquePointer(unretained)
    }
}