Working version.

Sources/CropImage/CropImageView.swift

@@ -6,15 +6,62 @@
 //
 
 import SwiftUI
+#if os(iOS)
+import UIKit
+#endif
 
 public struct CropImageView: View {
+    public enum RenderError: Error {
+        case imageRendererReturnedNil
+    }
+
     var image: PlatformImage
     var targetSize: CGSize
-    var onCrop: (PlatformImage) -> Void
+    var targetScale: CGFloat = 1
+    var onCrop: (Result<PlatformImage, Error>) -> Void
 
     @State private var offset: CGSize = .zero
     @State private var scale: CGFloat = 1
 
+    @MainActor
+    func crop() throws -> PlatformImage {
+        let snapshotView = MoveAndScalableImageView(offset: $offset, scale: $scale, image: image)
+            .frame(width: targetSize.width, height: targetSize.height)
+        if #available(iOS 16.0, macOS 13.0, *) {
+            let renderer = ImageRenderer(content: snapshotView)
+            renderer.scale = targetScale
+#if os(iOS)
+            if let image = renderer.uiImage {
+                return image
+            } else {
+                throw RenderError.imageRendererReturnedNil
+            }
+#elseif os(macOS)
+            if let image = renderer.nsImage {
+                return image
+            } else {
+                throw RenderError.imageRendererReturnedNil
+            }
+#endif
+        } else {
+#if os(macOS)
+            fatalError("Cropping is not supported on macOS versions before Ventrura 13.0.")
+#elseif os(iOS)
+            let window = UIWindow(frame: CGRect(origin: .zero, size: targetSize))
+            let hosting = UIHostingController(rootView: snapshotView)
+            hosting.view.frame = window.frame
+            window.addSubview(hosting.view)
+            window.makeKeyAndVisible()
+            UIGraphicsBeginImageContextWithOptions(hosting.view.bounds.size, false, targetScale)
+            let context = UIGraphicsGetCurrentContext()!
+            hosting.view.layer.render(in: context)
+            let image = UIGraphicsGetImageFromCurrentImageContext()!
+            UIGraphicsEndImageContext()
+            return image
+#endif
+        }
+    }
+
     public var body: some View {
         ZStack {
             MoveAndScalableImageView(offset: $offset, scale: $scale, image: image)
@@ -22,36 +69,79 @@ public struct CropImageView: View {
                 .fill(style: FillStyle(eoFill: true))
                 .foregroundColor(.black.opacity(0.6))
                 .allowsHitTesting(false)
+            VStack {
+                Spacer()
+                HStack {
+                    Spacer()
+                    Button { Task {
+                        do {
+                            onCrop(.success(try crop()))
+                        } catch {
+                            onCrop(.failure(error))
+                        }
+                    } } label: {
+                        Label("Crop", systemImage: "checkmark.circle.fill")
+                            .font(.title2)
+                            .foregroundColor(.accentColor)
+                            .labelStyle(.iconOnly)
+                            .padding(1)
+                            .background(
+                                Circle().fill(.white)
+                            )
+                    }
+                    .buttonStyle(.plain)
+                    .padding()
+                }
+            }
         }
     }
 }
 
 struct CropImageView_Previews: PreviewProvider {
     struct PreviewView: View {
-        @State private var croppedImage: PlatformImage? = nil
+        @State private var targetSize: CGSize = .init(width: 100, height: 100)
+        @State private var result: Result<PlatformImage, Error>? = nil
 
         var body: some View {
             VStack {
                 CropImageView(
                     image: .init(contentsOfFile: "/Users/laosb/Downloads/png.png")!,
-                    targetSize: .init(width: 100, height: 100)
+                    targetSize: targetSize
-                ) { _ in
+                ) { result = $0 }
-
+                Form {
-                }
+                    Section {
-                if let croppedImage {
+                        TextField("Width", value: $targetSize.width, formatter: NumberFormatter())
-                    #if os(macOS)
+                        TextField("Height", value: $targetSize.height, formatter: NumberFormatter())
-                    Image(nsImage: croppedImage)
+                    } header: { Text("Crop Target Size") }
-                    #elseif os(iOS)
+                    Section {
-                    Image(uiImage: croppedImage)
+                        if let result {
-                    #endif
+                            switch result {
-                } else {
+                            case let .success(croppedImage):
-                    Text("Press \(Image(systemName: "checkmark.circle.fill")) to crop.")
+#if os(macOS)
+                                Image(nsImage: croppedImage)
+#elseif os(iOS)
+                                Image(uiImage: croppedImage)
+#endif
+                            case let .failure(error):
+                                Text(error.localizedDescription)
+                                    .foregroundColor(.red)
+                            }
+                        } else {
+                            Text("Press \(Image(systemName: "checkmark.circle.fill")) to crop.")
+                        }
+                    } header: { Text("Result") }
                 }
+                #if os(macOS)
+                .formStyle(.grouped)
+                #endif
             }
         }
     }
 
     static var previews: some View {
         PreviewView()
+        #if os(macOS)
+            .frame(minHeight: 750)
+        #endif
     }
 }