Skip to content

Instantly share code, notes, and snippets.

Embed
What would you like to do?
Piece of Utility code to make CGImage from MTLTexture under (BGRA8Unorm)
//
// MTLTexture+Z.swift
// ZKit
//
// The MIT License (MIT)
//
// Copyright (c) 2016 Electricwoods LLC, Kaz Yoshikawa.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//
import Foundation
import CoreGraphics
import MetalKit
import GLKit
import Accelerate
extension MTLTexture {
#if os(iOS)
typealias XImage = UIImage
#elseif os(macOS)
typealias XImage = NSImage
#endif
var cgImage: CGImage? {
assert(self.pixelFormat == .bgra8Unorm)
// read texture as byte array
let rowBytes = self.width * 4
let length = rowBytes * self.height
let bgraBytes = [UInt8](repeating: 0, count: length)
let region = MTLRegionMake2D(0, 0, self.width, self.height)
self.getBytes(UnsafeMutableRawPointer(mutating: bgraBytes), bytesPerRow: rowBytes, from: region, mipmapLevel: 0)
// use Accelerate framework to convert from BGRA to RGBA
var bgraBuffer = vImage_Buffer(data: UnsafeMutableRawPointer(mutating: bgraBytes),
height: vImagePixelCount(self.height), width: vImagePixelCount(self.width), rowBytes: rowBytes)
let rgbaBytes = [UInt8](repeating: 0, count: length)
var rgbaBuffer = vImage_Buffer(data: UnsafeMutableRawPointer(mutating: rgbaBytes),
height: vImagePixelCount(self.height), width: vImagePixelCount(self.width), rowBytes: rowBytes)
let map: [UInt8] = [2, 1, 0, 3]
vImagePermuteChannels_ARGB8888(&bgraBuffer, &rgbaBuffer, map, 0)
// flipping image virtically
let flippedBytes = bgraBytes // share the buffer
var flippedBuffer = vImage_Buffer(data: UnsafeMutableRawPointer(mutating: flippedBytes),
height: vImagePixelCount(self.height), width: vImagePixelCount(self.width), rowBytes: rowBytes)
vImageVerticalReflect_ARGB8888(&rgbaBuffer, &flippedBuffer, 0)
// create CGImage with RGBA
let colorScape = CGColorSpaceCreateDeviceRGB()
let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.premultipliedLast.rawValue)
guard let data = CFDataCreate(nil, flippedBytes, length) else { return nil }
guard let dataProvider = CGDataProvider(data: data) else { return nil }
let cgImage = CGImage(width: self.width, height: self.height, bitsPerComponent: 8, bitsPerPixel: 32, bytesPerRow: rowBytes,
space: colorScape, bitmapInfo: bitmapInfo, provider: dataProvider,
decode: nil, shouldInterpolate: true, intent: .defaultIntent)
return cgImage
}
var image: XImage? {
guard let cgImage = self.cgImage else { return nil }
#if os(iOS)
return UIImage(cgImage: cgImage)
#elseif os(macOS)
return NSImage(cgImage: cgImage, size: CGSize(width: cgImage.width, height: cgImage.height))
#endif
}
}
@michaelamici

This comment has been minimized.

Copy link

michaelamici commented Sep 22, 2018

legendary

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.