Add a non-functional “ALT” button to MediaView

MastodonSDK/Sources/MastodonUI/View/Content/MediaAltTextOverlay.swift

@@ -0,0 +1,62 @@
+//
+//  MediaAltTextOverlay.swift
+//  
+//
+//  Created by Jed Fox on 2022-12-20.
+//
+
+import SwiftUI
+
+@available(iOS 15.0, *)
+struct MediaAltTextOverlay: View {
+    var altDescription: String?
+    
+    @State private var showingAlt = false
+
+    var body: some View {
+        HStack {
+            VStack {
+                Spacer(minLength: 0)
+                if altDescription != nil {
+                    Button("ALT") {}
+                        .buttonStyle(AltButtonStyle())
+                }
+            }
+            Spacer(minLength: 0)
+        }
+        .padding(.horizontal, 16)
+        .padding(.vertical, 8)
+        .onChange(of: altDescription) { _ in
+            showingAlt = false
+        }
+    }
+}
+
+@available(iOS 15.0, *)
+private struct AltButtonStyle: ButtonStyle {
+    @Environment(\.pixelLength) private var pixelLength
+    func makeBody(configuration: Configuration) -> some View {
+        configuration.label
+            .font(.caption.weight(.semibold))
+            .foregroundColor(.white)
+            .padding(.horizontal, 8)
+            .padding(.vertical, 3)
+            .background(Color.black.opacity(0.85))
+            .cornerRadius(4)
+            .opacity(configuration.isPressed ? 0.5 : 1)
+            .overlay(
+                .white.opacity(0.4),
+                in: RoundedRectangle(cornerRadius: 4)
+                    .inset(by: -0.5)
+                    .stroke(lineWidth: 0.5)
+            )
+    }
+}
+
+@available(iOS 15.0, *)
+struct MediaAltTextOverlay_Previews: PreviewProvider {
+    static var previews: some View {
+        MediaAltTextOverlay(altDescription: nil)
+        MediaAltTextOverlay(altDescription: "Hello, world!")
+    }
+}

MastodonSDK/Sources/MastodonUI/View/Content/MediaView.swift

@@ -10,6 +10,7 @@ import AVKit
 import UIKit
 import Combine
 import AlamofireImage
+import SwiftUI
 
 public final class MediaView: UIView {
     
@@ -71,6 +72,20 @@ public final class MediaView: UIView {
         return label
     }()
     
+    let _altViewController: UIViewController! = {
+        if #available(iOS 15.0, *) {
+            let vc = UIHostingController(rootView: MediaAltTextOverlay())
+            vc.view.backgroundColor = .clear
+            return vc
+        } else {
+            return nil
+        }
+    }()
+    @available(iOS 15.0, *)
+    var altViewController: UIHostingController<MediaAltTextOverlay> {
+        _altViewController as! UIHostingController<MediaAltTextOverlay>
+    }
+    
     public override init(frame: CGRect) {
         super.init(frame: frame)
         _init()
@@ -133,6 +148,7 @@ extension MediaView {
         imageView.translatesAutoresizingMaskIntoConstraints = false
         container.addSubview(imageView)
         imageView.pinToParent()
+        layoutAlt()
     }
     
     private func bindImage(configuration: Configuration, info: Configuration.ImageInfo) {        
@@ -151,6 +167,9 @@ extension MediaView {
             self.imageView.image = image
         }
         .store(in: &configuration.disposeBag)
+        if #available(iOS 15.0, *) {
+            altViewController.rootView.altDescription = info.altDescription
+        }
     }
         
     private func layoutGIF() {
@@ -161,6 +180,8 @@ extension MediaView {
         
         setupIndicatorViewHierarchy()
         playerIndicatorLabel.attributedText = NSAttributedString(string: "GIF")
+        
+        layoutAlt()
     }
     
     private func bindGIF(configuration: Configuration, info: Configuration.VideoInfo) {
@@ -171,6 +192,9 @@ extension MediaView {
         
         // auto play for GIF
         player.play()
+        if #available(iOS 15.0, *) {
+            altViewController.rootView.altDescription = info.altDescription
+        }
     }
     
     private func layoutVideo() {
@@ -223,6 +247,14 @@ extension MediaView {
             .store(in: &_disposeBag)
     }
     
+    private func layoutAlt() {
+        if #available(iOS 15.0, *) {
+            altViewController.view.translatesAutoresizingMaskIntoConstraints = false
+            container.addSubview(altViewController.view)
+            altViewController.view.pinToParent()
+        }
+    }
+    
     public func prepareForReuse() {
         _disposeBag.removeAll()
         
@@ -258,6 +290,10 @@ extension MediaView {
         container.removeFromSuperview()
         container.removeConstraints(container.constraints)
         
+        if #available(iOS 15.0, *) {
+            altViewController.rootView.altDescription = nil
+        }
+        
         // reset configuration
         configuration = nil
     }