context menu for copy / share image

Changelog-Added: Added ability to copy and share image (@futurepaul)

damus/Components/ImageCarousel.swift

@@ -8,9 +8,78 @@
 import SwiftUI
 import Kingfisher
 
+// TODO: all this ShareSheet complexity can be replaced with ShareLink once we update to iOS 16
+struct ShareSheet: UIViewControllerRepresentable {
+    typealias Callback = (_ activityType: UIActivity.ActivityType?, _ completed: Bool, _ returnedItems: [Any]?, _ error: Error?) -> Void
+    
+    let activityItems: [URL]
+    let callback: Callback? = nil
+    let applicationActivities: [UIActivity]? = nil
+    let excludedActivityTypes: [UIActivity.ActivityType]? = nil
+    
+    func makeUIViewController(context: Context) -> UIActivityViewController {
+        let controller = UIActivityViewController(
+            activityItems: activityItems,
+            applicationActivities: applicationActivities)
+        controller.excludedActivityTypes = excludedActivityTypes
+        controller.completionWithItemsHandler = callback
+        return controller
+    }
+    
+    func updateUIViewController(_ uiViewController: UIActivityViewController, context: Context) {
+        // nothing to do here
+    }
+}
+
+struct ImageContextMenuModifier: ViewModifier {
+    let url: URL
+    let image: UIImage?
+    @Binding var showShareSheet: Bool
+    
+    func body(content: Content) -> some View {
+        return content.contextMenu {
+            Button {
+                UIPasteboard.general.url = url
+            } label: {
+                Label("Copy Image URL", systemImage: "doc.on.doc")
+            }
+            if let someImage = image {
+                Button {
+                    UIPasteboard.general.image = someImage
+                } label: {
+                    Label("Copy Image", systemImage: "photo.on.rectangle")
+                }
+            }
+            Button {
+                showShareSheet = true
+            } label: {
+                Label("Share", systemImage: "square.and.arrow.up")
+            }
+        }
+    }
+}
+
 struct ImageViewer: View {
     let urls: [URL]
     
+    private struct ImageHandler: ImageModifier {
+        @Binding var handler: UIImage?
+        
+        func modify(_ image: UIImage) -> UIImage {
+            handler = image
+            return image
+        }
+    }
+
+    @State private var image: UIImage?
+    @State private var showShareSheet = false
+    
+    func onShared(completed: Bool) -> Void {
+        if (completed) {
+            showShareSheet = false
+        }
+    }
+    
     var body: some View {
         TabView {
             ForEach(urls, id: \.absoluteString) { url in
@@ -22,6 +91,7 @@ struct ImageViewer: View {
                             view.framePreloadCount = 3
                         }
                         .cacheOriginalImage()
+                        .imageModifier(ImageHandler(handler: $image))
                         .loadDiskFileSynchronously()
                         .scaleFactor(UIScreen.main.scale)
                         .fade(duration: 0.1)
@@ -30,6 +100,11 @@ struct ImageViewer: View {
                             Text(url.absoluteString)
                         }
                         .id(url.absoluteString)
+                        .modifier(ImageContextMenuModifier(url: url, image: image, showShareSheet: $showShareSheet))
+                        .sheet(isPresented: $showShareSheet) {
+                            ShareSheet(activityItems: [url])
+                        }
+
                 }
             }
         }