Return ShimmerModifier

Package.swift

@@ -8,7 +8,7 @@ let package = Package(
     platforms: [
         .iOS(.v13),
         .watchOS(.v7),
-        .macOS(.v11)
+        .macOS(.v12)
     ], 
     products: [
         // Products define the executables and libraries a package produces, and make them visible to other packages.

README.md

@@ -117,6 +117,7 @@ func cornerRadius(_ radius: CGFloat, corners: UIRectCorner)
 func onRotate(perform action: @escaping (UIDeviceOrientation) -> Void)
 func rotateHandling(anchor: UnitPoint = .center)
 func rotated(_ angle: Angle)
+func shimmer(isActive: Bool = true, speed: Double = 0.15, angle: Angle = .init(degrees: 70), opacity: Double = 1.0)
 ```
 
 Shapes:

Sources/HelpersSwiftUI/View/Modifiers/ShimmerModifier.swift

@@ -0,0 +1,76 @@
+//
+//  ShimmerModifier.swift
+//  
+//
+//  Created by Mykola Fiantsev on 27.05.2023.
+//
+
+import SwiftUI
+
+public extension View {
+  func shimmer(isActive: Bool = true, speed: Double = 0.15, angle: Angle = .init(degrees: 70), opacity: Double = 1.0) -> some View {
+    return self.modifier(ShimmerModifier(isActive: isActive, speed: speed, angle: angle, opacity: opacity))
+  }
+}
+
+private struct ShimmerModifier: ViewModifier {
+  let isActive: Bool
+  let speed: Double
+  let angle: Angle
+  let opacity: Double
+
+  @ViewBuilder
+  func body(content: Content) -> some View {
+    if !isActive { content }
+
+    content
+      .opacity(opacity)
+      .overlay(ShimmerView(speed: speed, angle: angle).mask(content))
+  }
+}
+
+private struct ShimmerView: View {
+  let speed: Double
+  let angle: Angle
+  @State private var _show = false
+
+  var body: some View {
+    GeometryReader { geo in
+      Color.white
+        .mask(Rectangle().fill(_gradient))
+        .padding(-_calcSize(geo))
+        .rotationEffect(angle)
+        .offset(x: _calcOffset(geo), y: 0)
+        .animation(_animation)
+    }
+    .onAppear { _show.toggle() }
+  }
+
+  private var _gradient: LinearGradient {
+    let leading = Gradient.Stop(color: .clear, location: 0.35)
+    let center = Gradient.Stop(color: Color.white.opacity(0.7), location: 0.45)
+    let trailing = Gradient.Stop(color: .clear, location: 0.55)
+
+    return LinearGradient(
+      gradient: .init(stops: [leading, center, trailing]),
+      startPoint: .top,
+      endPoint: .bottom
+    )
+  }
+
+  private var _animation: Animation {
+    Animation.default
+      .speed(0.15)
+      .delay(0)
+      .repeatForever(autoreverses: false)
+  }
+
+  private func _calcOffset(_ geo: GeometryProxy) -> CGFloat {
+    let size = _calcSize(geo)
+    return (_show ? size : -size) * 2
+  }
+
+  private func _calcSize(_ geo: GeometryProxy) -> CGFloat {
+    return max(geo.size.width, geo.size.height)
+  }
+}