🅿️GeometryEffect

⭐️ 重點

When an animatable modifier animates something that can be expressed as an affine transformation (2D/3D), we can also use GeometryEffect instead of Animatable Modifiers.

💈範例

struct ShakeEffect: GeometryEffect {

    var times: CGFloat = 0 
    let amplitude: CGFloat = 10 
    
    // ⭐️ 🅿️ Animatable
    var animatableData: CGFloat { 
        get { times } 
        set { times = newValue } 
    }
    
    // ⭐️ 🅿️ GeometryEffect
    func effectValue(size: CGSize) -> ProjectionTransform { 
        ProjectionTransform(CGAffineTransform( 
            translationX: sin(times * .pi * 2) * amplitude, y: 0 
        )) 
    }
}

📘 手冊

• SwiftUI ⟩

  • Drawing and Graphics ⟩ ProjectionTransform (struct) - 3x3 matrix.

  • Animations ⟩ GeometryEffect (protocol)

    • .effectValue(size:) - required instance method.

📜 協定

📗 參考

• SwiftUI Lab ⟩ Advanced SwiftUI Animations ⟩

  • Part 2: GeometryEffect