Created
February 29, 2024 23:04
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import UIKit | |
import MetalKit | |
class ViewController: UIViewController { | |
override func viewDidAppear(_ animated: Bool) { | |
super.viewDidAppear(animated) | |
let imageView = UIImageView(image: UIImage(named: "landscape.jpeg")) | |
imageView.frame = CGRect(x: 0, y: 200, width: 350, height: 197) | |
view.addSubview(imageView) | |
DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(3)) { | |
// CARenderer outputs 350 🤕 | |
let texture = imageView.snapshot(device: MTLCreateSystemDefaultDevice()!)! | |
print(texture.width) | |
let image = UIImage(ciImage: CIImage(mtlTexture: texture)!) | |
print(image.size.width * image.scale) | |
// UIView.drawHierarchy outputs 1,050 as expected 🥳 | |
let rendererFormat = UIGraphicsImageRendererFormat.default() | |
rendererFormat.opaque = true | |
let renderer = UIGraphicsImageRenderer(size: imageView.bounds.size, format: rendererFormat) | |
let image2 = renderer.image { context in | |
imageView.drawHierarchy(in: imageView.bounds, afterScreenUpdates: false) | |
} | |
print(image2.size.width * image2.scale) | |
} | |
} | |
} | |
extension UIView { | |
func snapshot(device: MTLDevice) -> MTLTexture? { | |
let width = Int(bounds.width) | |
let height = Int(bounds.height) | |
let desc = MTLTextureDescriptor.texture2DDescriptor(pixelFormat: .rgba8Unorm, width: width, height: height, mipmapped: false) | |
desc.usage = [.renderTarget, .shaderRead, .shaderWrite] | |
let texture = device.makeTexture(descriptor: desc)! | |
let renderer = CARenderer(mtlTexture: texture) | |
renderer.layer = layer | |
renderer.bounds = CGRect(x: 0, y: 0, width: width, height: height) | |
CATransaction.flush() | |
renderer.beginFrame(atTime: CACurrentMediaTime(), timeStamp: nil) | |
renderer.addUpdate(CGRect(x: 0, y: 0, width: width, height: height)) | |
renderer.render() | |
renderer.endFrame() | |
return texture | |
} | |
} | |
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