Add UIWindow subclass to display all touches.

MastodonSDK/Sources/MastodonUI/View/Window/TouchesVisibleWindow.swift

@@ -0,0 +1,134 @@
+//
+//  File.swift
+//  
+//
+//  Created by Chase Carroll on 12/5/22.
+//
+
+#if DEBUG
+
+import UIKit
+
+fileprivate final class TouchView: UIView {
+    
+    fileprivate lazy var blurView: UIVisualEffectView = {
+        let blurEffect = UIBlurEffect(style: .systemUltraThinMaterialLight)
+        return UIVisualEffectView(effect: blurEffect)
+    }()
+    
+    override var frame: CGRect {
+        didSet {
+            layer.cornerRadius = frame.height / 2.0
+        }
+    }
+    
+    override init(frame: CGRect) {
+        super.init(frame: frame)
+        
+        backgroundColor = .clear
+        layer.masksToBounds = true
+        layer.cornerCurve = .circular
+        layer.borderColor = UIColor.white.cgColor
+        layer.borderWidth = 2.0
+        
+        addSubview(blurView)
+    }
+    
+    @available(iOS, unavailable)
+    required init?(coder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+    
+    override func layoutSubviews() {
+        super.layoutSubviews()
+        blurView.frame = bounds
+    }
+    
+}
+
+
+public final class TouchesVisibleWindow: UIWindow {
+    
+    var touchesVisible = false {
+        didSet {
+            if !touchesVisible {
+                cleanUpAllTouches()
+            }
+        }
+    }
+    
+    fileprivate var touchViews: [UITouch : TouchView] = [:]
+    
+    fileprivate func newTouchView() -> TouchView {
+        let touchSize = 44.0
+        return TouchView(frame: CGRect(
+            origin: .zero,
+            size: CGSize(
+                width: touchSize,
+                height: touchSize
+            )
+        ))
+    }
+    
+    fileprivate func cleanupTouch(_ touch: UITouch) {
+        guard let touchView = touchViews[touch] else {
+            return
+        }
+        
+        touchView.removeFromSuperview()
+        touchViews.removeValue(forKey: touch)
+    }
+    
+    fileprivate func cleanUpAllTouches() {
+        for (_, touchView) in touchViews {
+            touchView.removeFromSuperview()
+        }
+        
+        touchViews.removeAll()
+    }
+    
+    public override func sendEvent(_ event: UIEvent) {
+        if !touchesVisible {
+            super.sendEvent(event)
+            return
+        }
+        
+        let touches = event.allTouches
+        
+        guard
+            let touches = touches,
+            touches.count > 0
+        else {
+            cleanUpAllTouches()
+            super.sendEvent(event)
+            return
+        }
+        
+        for touch in touches {
+            let touchLocation = touch.location(in: self)
+            switch touch.phase {
+            case .began:
+                let touchView = newTouchView()
+                touchView.center = touchLocation
+                addSubview(touchView)
+                touchViews[touch] = touchView
+                
+            case .moved:
+                guard let touchView = touchViews[touch] else {
+                    return
+                }
+                touchView.center = touchLocation
+                
+            case .ended, .cancelled:
+                cleanupTouch(touch)
+                
+            default:
+                break
+            }
+        }
+        
+        super.sendEvent(event)
+    }
+}
+
+#endif