Add snapshots

Sources/Pow/Infrastructure/ProgressableAnimation.swift

@@ -0,0 +1,62 @@
+//
+//  ProgressableAnimation.swift
+//
+//
+//  Created by Noah Martin on 11/30/23.
+//
+
+import Foundation
+import SwiftUI
+
+#if DEBUG
+typealias DebugProgressableAnimation = ProgressableAnimation
+#else
+typealias DebugProgressableAnimation = Animatable
+#endif
+
+protocol ProgressableAnimation: Animatable {
+  var progress: CGFloat { get set }
+}
+
+extension ProgressableAnimation where AnimatableData == CGFloat {
+  var progress: CGFloat {
+    get { animatableData }
+    set { animatableData = newValue }
+  }
+}
+
+#if DEBUG
+protocol PreviewableAnimation {
+  associatedtype Animation: ProgressableAnimation & ViewModifier
+
+  static var animation: Animation { get }
+
+  static var content: any View { get }
+}
+
+extension PreviewableAnimation {
+  static var content: any View {
+    RoundedRectangle(
+      cornerRadius: 8,
+      style: .continuous)
+    .fill(Color.blue)
+    .frame(width: 80, height: 80)
+  }
+}
+
+extension PreviewableAnimation {
+  static var previews: AnyView {
+    let c = self.content
+    let anyContent = AnyView(c)
+    let modifiers = [0, 0.25, 0.5, 0.75, 1].map { i in
+      var copy = self.animation
+      copy.progress = i
+      return copy
+    }
+    return AnyView(ForEach(Array(modifiers.enumerated()), id: \.offset) { i, modifier in
+      anyContent.modifier(modifier)
+        .previewDisplayName("\(String(describing: Animation.self))-\(i)")
+    })
+  }
+}
+#endif

Sources/Pow/Infrastructure/Scaled.swift

@@ -26,3 +26,5 @@ internal struct Scaled<V: ViewModifier & Animatable>: ViewModifier, Animatable {
         content.modifier(base.animation(nil))
     }
 }
+
+extension Scaled: ProgressableAnimation where V.AnimatableData == CGFloat { }

Sources/Pow/Transitions/Anvil.swift

@@ -19,7 +19,7 @@ public extension AnyTransition.MovingParts {
     }
 }
 
-internal struct Anvil: ViewModifier, Animatable, AnimatableModifier {
+internal struct Anvil: ViewModifier, ProgressableAnimation, AnimatableModifier {
     var animatableData: CGFloat = 0
 
     #if os(iOS)
@@ -31,11 +31,6 @@ internal struct Anvil: ViewModifier, Animatable, AnimatableModifier {
         self.animatableData = animatableData
     }
 
-    var progress: CGFloat {
-        get { animatableData }
-        set { animatableData = newValue }
-    }
-
     func body(content: Content) -> some View {
         /// Fraction of the animation spent on the view falling down.
         let fall: CGFloat = 0.1
@@ -212,6 +207,21 @@ extension EdgeInsets {
 }
 
 #if os(iOS) && DEBUG
+struct Anvil_Preview: PreviewableAnimation, PreviewProvider {
+  static var animation: Anvil {
+    Anvil(animatableData: 0)
+  }
+
+  static var content: any View {
+    RoundedRectangle(
+      cornerRadius: 8,
+      style: .continuous)
+    .fill(Color.blue)
+    .frame(width: 80, height: 80)
+    .preferredColorScheme(.dark)
+  }
+}
+
 @available(iOS 15.0, *)
 struct Anvil_Previews: PreviewProvider {
     struct Item: Identifiable {

Sources/Pow/Transitions/Blinds.swift

@@ -30,7 +30,7 @@ public extension AnyTransition.MovingParts {
     }
 }
 
-internal struct Blinds: ViewModifier, Animatable, AnimatableModifier, Hashable {
+internal struct Blinds: ViewModifier, ProgressableAnimation, AnimatableModifier, Hashable {
     var slatWidth: CGFloat
 
     var style: AnyTransition.MovingParts.BlindsStyle
@@ -39,11 +39,6 @@ internal struct Blinds: ViewModifier, Animatable, AnimatableModifier, Hashable {
 
     var animatableData: CGFloat
 
-    private var progress: CGFloat {
-        get { animatableData }
-        set { animatableData = newValue }
-    }
-
     func body(content: Content) -> some View {
         content
             .mask {
@@ -108,6 +103,13 @@ private struct BlindsShape: Shape {
 }
 
 #if os(iOS) && DEBUG
+struct Blinds_Preview: PreviewableAnimation & PreviewProvider {
+
+  static var animation: Blinds {
+    Blinds(slatWidth: 20, style: .venetian, isStaggered: false, animatableData: 0)
+  }
+}
+
 @available(iOS 15.0, *)
 struct Blinds_Previews: PreviewProvider {
     struct Preview: View {

Sources/Pow/Transitions/Blur.swift

@@ -22,7 +22,7 @@ public extension AnyTransition.MovingParts {
     }
 }
 
-internal struct Blur: ViewModifier, Animatable, AnimatableModifier, Hashable {
+internal struct Blur: ViewModifier, DebugProgressableAnimation, AnimatableModifier, Hashable {
     var animatableData: CGFloat {
         get { radius }
         set { radius = newValue }
@@ -37,6 +37,12 @@ internal struct Blur: ViewModifier, Animatable, AnimatableModifier, Hashable {
 }
 
 #if os(iOS) && DEBUG
+struct Blur_Preview: PreviewableAnimation, PreviewProvider {
+  static var animation: Blur {
+    Blur(radius: 30)
+  }
+}
+
 @available(iOS 15.0, *)
 struct Blur_Previews: PreviewProvider {
     struct Preview: View {

Sources/Pow/Transitions/Boing.swift

@@ -21,7 +21,7 @@ public extension AnyTransition.MovingParts {
     }
 }
 
-internal struct Boing: Animatable, GeometryEffect {
+internal struct Boing: DebugProgressableAnimation, GeometryEffect {
     var edge: Edge
 
     var animatableData: CGFloat = 0
@@ -107,6 +107,12 @@ internal struct Boing: Animatable, GeometryEffect {
 }
 
 #if os(iOS) && DEBUG
+struct Boing_Preview: PreviewableAnimation, PreviewProvider {
+  static var animation: Scaled<Boing> {
+    Scaled(Boing(.top, animatableData: 0))
+  }
+}
+
 @available(iOS 15.0, *)
 struct Bounce_Previews: PreviewProvider {
     struct Item: Identifiable {

Sources/Pow/Transitions/Clock.swift

@@ -21,7 +21,8 @@ public extension AnyTransition.MovingParts {
     }
 }
 
-internal struct Clock: ViewModifier, Animatable, AnimatableModifier {
+internal struct Clock: ViewModifier, DebugProgressableAnimation, AnimatableModifier {
+
     var origin: UnitPoint
 
     var animatableData: AnimatablePair<CGFloat, CGFloat>
@@ -32,7 +33,8 @@ internal struct Clock: ViewModifier, Animatable, AnimatableModifier {
     }
 
     var progress: CGFloat {
-        animatableData.first
+      get { animatableData.first }
+      set { animatableData.first = newValue }
     }
 
     var blurRadius: CGFloat {
@@ -84,6 +86,12 @@ internal struct Clock: ViewModifier, Animatable, AnimatableModifier {
 }
 
 #if os(iOS) && DEBUG
+struct Clock_Preview: PreviewableAnimation, PreviewProvider {
+  static var animation: Clock {
+    Clock(origin: .center, blurRadius: 0, progress: 0)
+  }
+}
+
 struct Clock_Previews: PreviewProvider {
     struct Item: Identifiable {
         var color: Color

Sources/Pow/Transitions/FilmExposure.swift

@@ -20,14 +20,9 @@ public extension AnyTransition.MovingParts {
     }
 }
 
-internal struct Snapshot: ViewModifier, Animatable, AnimatableModifier, Hashable {
+internal struct Snapshot: ViewModifier, ProgressableAnimation, AnimatableModifier, Hashable {
     var animatableData: CGFloat = 0
 
-    var progress: CGFloat {
-        get { animatableData }
-        set { animatableData = newValue }
-    }
-
     func body(content: Content) -> some View {
         content
             .saturation(0.5 + 0.5 * clamp(progress))
@@ -38,14 +33,9 @@ internal struct Snapshot: ViewModifier, Animatable, AnimatableModifier, Hashable
     }
 }
 
-internal struct ExposureFade: ViewModifier, Animatable, AnimatableModifier, Hashable {
+internal struct ExposureFade: ViewModifier, ProgressableAnimation, AnimatableModifier, Hashable {
     var animatableData: CGFloat = 0
 
-    var progress: CGFloat {
-        get { animatableData }
-        set { animatableData = newValue }
-    }
-
     func body(content: Content) -> some View {
         content
             .opacity(Double(1.0 - pow(2.0, -10.0 * progress)))
@@ -55,6 +45,18 @@ internal struct ExposureFade: ViewModifier, Animatable, AnimatableModifier, Hash
 }
 
 #if os(iOS) && DEBUG
+struct Snapshot_Preview: PreviewableAnimation, PreviewProvider {
+  static var animation: Snapshot {
+    Snapshot(animatableData: 0)
+  }
+}
+
+struct FilmExposure_Preview: PreviewableAnimation, PreviewProvider {
+  static var animation: ExposureFade {
+    ExposureFade(animatableData: 0)
+  }
+}
+
 @available(iOS 15.0, *)
 struct ExoposureFade_Previews: PreviewProvider {
     struct Preview: View {

Sources/Pow/Transitions/Flicker.swift

@@ -21,16 +21,11 @@ public extension AnyTransition.MovingParts {
     }
 }
 
-internal struct Flicker: ViewModifier, Animatable, AnimatableModifier, Hashable {
+internal struct Flicker: ViewModifier, ProgressableAnimation, AnimatableModifier, Hashable {
     var count: Int
 
     var animatableData: CGFloat
 
-    private var progress: CGFloat {
-        get { animatableData }
-        set { animatableData = newValue }
-    }
-
     private var isVisible: Bool {
         (progress * CGFloat(count)).remainder(dividingBy: 1) >= 0
     }
@@ -43,6 +38,12 @@ internal struct Flicker: ViewModifier, Animatable, AnimatableModifier, Hashable
 }
 
 #if os(iOS) && DEBUG
+struct Flicker_Preview: PreviewableAnimation, PreviewProvider {
+  static var animation: Flicker {
+    Flicker(count: 1, animatableData: 0)
+  }
+}
+
 @available(iOS 15.0, *)
 struct Flicker_Previews: PreviewProvider {
     struct Preview: View {

Sources/Pow/Transitions/Glare.swift

@@ -47,7 +47,7 @@ public extension AnyTransition.MovingParts {
     }
 }
 
-internal struct Glare: ViewModifier, Animatable, AnimatableModifier {
+internal struct Glare: ViewModifier, DebugProgressableAnimation, AnimatableModifier {
     var animatableData: CGFloat = 0
 
     var angle: Angle
@@ -132,8 +132,37 @@ internal struct Glare: ViewModifier, Animatable, AnimatableModifier {
 }
 
 #if os(iOS) && DEBUG
+@available(iOS 16.0, *)
+struct Glare_Preview: PreviewableAnimation, PreviewProvider {
+  static var animation: Glare {
+    Glare(.degrees(45), color: .white, increasedBrightness: true, animatableData: 0)
+  }
+
+  static var content: any View {
+    Glare_Previews.makeRect(start: .indigo, end: .purple)
+        .frame(width: 100, height: 100)
+        .preferredColorScheme(.dark)
+  }
+}
+
 @available(iOS 16.0, *)
 struct Glare_Previews: PreviewProvider {
+  static func makeRect(start: Color, end: Color) -> some View {
+    RoundedRectangle(cornerRadius: 18, style: .continuous)
+        .fill(LinearGradient(
+          colors: [start, end],
+            startPoint: .topLeading,
+            endPoint: .bottom
+        ))
+        .compositingGroup()
+        .overlay {
+            Text("Hello\nWorld")
+                .foregroundStyle(.white.shadow(.inner(radius: 0.5)))
+        }
+        .font(.system(.largeTitle, design: .rounded).weight(.medium))
+        .multilineTextAlignment(.center)
+  }
+
     struct Item: Identifiable {
         var color1: Color
         var color2: Color
@@ -214,19 +243,7 @@ struct Glare_Previews: PreviewProvider {
                         ForEach(items.indices, id: \.self) { index in
                             let item = items[index]
 
-                            RoundedRectangle(cornerRadius: 18, style: .continuous)
-                                .fill(LinearGradient(
-                                    colors: [item.color1, item.color2],
-                                    startPoint: .topLeading,
-                                    endPoint: .bottom
-                                ))
-                                .compositingGroup()
-                                .overlay {
-                                    Text("Hello\nWorld")
-                                        .foregroundStyle(.white.shadow(.inner(radius: 0.5)))
-                                }
-                                .font(.system(.largeTitle, design: .rounded).weight(.medium))
-                                .multilineTextAlignment(.center)
+                            Glare_Previews.makeRect(start: item.color1, end: item.color2)
                                 .transition(
                                     .asymmetric(
                                         insertion: .movingParts.glare(angle: angle),

Sources/Pow/Transitions/Iris.swift

@@ -15,7 +15,7 @@ public extension AnyTransition.MovingParts {
     }
 }
 
-private struct Iris: ViewModifier, Animatable, AnimatableModifier {
+struct Iris: ViewModifier, DebugProgressableAnimation, AnimatableModifier {
     var origin: UnitPoint
 
     var blurRadius: CGFloat
@@ -58,6 +58,12 @@ private struct Iris: ViewModifier, Animatable, AnimatableModifier {
 }
 
 #if os(iOS) && DEBUG
+struct Iris_Preview: PreviewableAnimation, PreviewProvider {
+  static var animation: Iris {
+    Iris(origin: .center, animatableData: 0)
+  }
+}
+
 @available(iOS 15.0, *)
 struct Mask_Previews: PreviewProvider {
     struct Preview: View {