如何控制阴影扩散和模糊？

Question

我在 sketch 中设计了 UI 个元素，其中一个元素有一个模糊为 1 且扩散为 0 的阴影。我查看了视图层的文档属性并且图层没有有任何名为 spread 或 blur 的东西，或任何等效的东西（唯一的控件只是 shadowOpacity）。如何控制模糊和扩散之类的东西？

以下是我在 Sketch 中的设置：

这就是我想要的影子：

这是目前的样子：

请注意，您必须单击图片才能真正看到阴影。

我的代码如下：

func setupLayer(){
    view.layer.cornerRadius = 2
    view.layer.shadowColor = Colors.Shadow.CGColor
    view.layer.shadowOffset = CGSize(width: 0, height: 1)
    view.layer.shadowOpacity = 0.9
    view.layer.shadowRadius = 5
}

Answer 1

你可以试试这个....你可以玩这些值。 shadowRadius 指示模糊量。 shadowOffset 指示阴影的去向。

Swift 2.0

let radius: CGFloat = demoView.frame.width / 2.0 //change it to .height if you need spread for height
let shadowPath = UIBezierPath(rect: CGRect(x: 0, y: 0, width: 2.1 * radius, height: demoView.frame.height))
//Change 2.1 to amount of spread you need and for height replace the code for height

demoView.layer.cornerRadius = 2
demoView.layer.shadowColor = UIColor.blackColor().CGColor
demoView.layer.shadowOffset = CGSize(width: 0.5, height: 0.4)  //Here you control x and y
demoView.layer.shadowOpacity = 0.5
demoView.layer.shadowRadius = 5.0 //Here your control your blur
demoView.layer.masksToBounds =  false
demoView.layer.shadowPath = shadowPath.CGPath

Swift 3.0

let radius: CGFloat = demoView.frame.width / 2.0 //change it to .height if you need spread for height 
let shadowPath = UIBezierPath(rect: CGRect(x: 0, y: 0, width: 2.1 * radius, height: demoView.frame.height)) 
//Change 2.1 to amount of spread you need and for height replace the code for height

demoView.layer.cornerRadius = 2
demoView.layer.shadowColor = UIColor.black.cgColor
demoView.layer.shadowOffset = CGSize(width: 0.5, height: 0.4)  //Here you control x and y
demoView.layer.shadowOpacity = 0.5
demoView.layer.shadowRadius = 5.0 //Here your control your blur
demoView.layer.masksToBounds =  false
demoView.layer.shadowPath = shadowPath.cgPath

Example with spread

To create a basic shadow

    demoView.layer.cornerRadius = 2
    demoView.layer.shadowColor = UIColor.blackColor().CGColor
    demoView.layer.shadowOffset = CGSizeMake(0.5, 4.0); //Here your control your spread
    demoView.layer.shadowOpacity = 0.5 
    demoView.layer.shadowRadius = 5.0 //Here your control your blur

Basic Shadow example in Swift 2.0

Answer 2

这段代码对我来说效果很好：

yourView.layer.shadowOpacity = 0.2 // opacity, 20%
yourView.layer.shadowColor = UIColor.black.cgColor
yourView.layer.shadowRadius = 2 // HALF of blur
yourView.layer.shadowOffset = CGSize(width: 0, height: 2) // Spread x, y
yourView.layer.masksToBounds = false

Answer 3

我的解决方案基于此 post 回复：(Swift 3)

let shadowPath = UIBezierPath(rect: CGRect(x: -1,
                                           y: -2,
                                           width: target.frame.width + 2,
                                           height: target.frame.height + 2))

target.layer.shadowColor = UIColor(hexString: shadowColor).cgColor
target.layer.shadowOffset = CGSize(width: CGFloat(shadowOffsetX), height: CGFloat(shadowOffsetY))
target.layer.masksToBounds = false
target.layer.shadowOpacity = Float(shadowOpacity)
target.layer.shadowPath = shadowPath.cgPath

Answer 4

以下是如何将所有 6 个 Sketch 阴影属性以近乎完美的精度应用到 UIView 的图层：

extension CALayer {
  func applySketchShadow(
    color: UIColor = .black,
    alpha: Float = 0.5,
    x: CGFloat = 0,
    y: CGFloat = 2,
    blur: CGFloat = 4,
    spread: CGFloat = 0)
  {
    masksToBounds = false
    shadowColor = color.cgColor
    shadowOpacity = alpha
    shadowOffset = CGSize(width: x, height: y)
    shadowRadius = blur / 2.0
    if spread == 0 {
      shadowPath = nil
    } else {
      let dx = -spread
      let rect = bounds.insetBy(dx: dx, dy: dx)
      shadowPath = UIBezierPath(rect: rect).cgPath
    }
  }
}

假设我们要表示以下内容：

您可以通过以下方式轻松完成此操作：

myView.layer.applySketchShadow(
  color: .black, 
  alpha: 0.5, 
  x: 0, 
  y: 0, 
  blur: 4, 
  spread: 0)

或更简洁：

myView.layer.applySketchShadow(y: 0)

示例：

Left: iPhone 8 UIView screenshot; right: Sketch rectangle.

注：

当使用非零 spread 时，它会根据 CALayer 的 bounds 硬编码路径。如果图层的边界发生变化，您需要再次调用 applySketchShadow() 方法。

Answer 5

在 Swift 4

中使用 IBDesignable 和 IBInspectable 绘制阴影

SKETCH AND XCODE SIDE BY SIDE

CODE

@IBDesignable class ShadowView: UIView {

    @IBInspectable var shadowColor: UIColor? {
        get {
            if let color = layer.shadowColor {
                return UIColor(cgColor: color)
            }
            return nil
        }
        set {
            if let color = newValue {
                layer.shadowColor = color.cgColor
            } else {
                layer.shadowColor = nil
            }
        }
    }

    @IBInspectable var shadowOpacity: Float {
        get {
            return layer.shadowOpacity
        }
        set {
            layer.shadowOpacity = newValue
        }
    }

    @IBInspectable var shadowOffset: CGPoint {
        get {
            return CGPoint(x: layer.shadowOffset.width, y:layer.shadowOffset.height)
        }
        set {
            layer.shadowOffset = CGSize(width: newValue.x, height: newValue.y)
        }

     }

    @IBInspectable var shadowBlur: CGFloat {
        get {
            return layer.shadowRadius
        }
        set {
            layer.shadowRadius = newValue / 2.0
        }
    }

    @IBInspectable var shadowSpread: CGFloat = 0 {
        didSet {
            if shadowSpread == 0 {
                layer.shadowPath = nil
            } else {
                let dx = -shadowSpread
                let rect = bounds.insetBy(dx: dx, dy: dx)
                layer.shadowPath = UIBezierPath(rect: rect).cgPath
            }
        }
    }
}

OUTPUT

HOW TO USE IT

Answer 6

对于那些试图将阴影应用到预定义路径（例如圆形视图）的人，这是我最终得到的结果：

extension CALayer {
    func applyShadow(color: UIColor = .black,
                     alpha: Float = 0.5,
                     x: CGFloat = 0,
                     y: CGFloat = 2,
                     blur: CGFloat = 4,
                     spread: CGFloat = 0,
                     path: UIBezierPath? = nil) {
        shadowColor = color.cgColor
        shadowOpacity = alpha
        shadowRadius = blur / 2
        if let path = path {
            if spread == 0 {
                shadowOffset = CGSize(width: x, height: y)
            } else {
                let scaleX = (path.bounds.width + (spread * 2)) / path.bounds.width
                let scaleY = (path.bounds.height + (spread * 2)) / path.bounds.height

                path.apply(CGAffineTransform(translationX: x + -spread, y: y + -spread).scaledBy(x: scaleX, y: scaleY))
                shadowPath = path.cgPath
            }
        } else {
            shadowOffset = CGSize(width: x, height: y)
            if spread == 0 {
                shadowPath = nil
            } else {
                let dx = -spread
                let rect = bounds.insetBy(dx: dx, dy: dx)
                shadowPath = UIBezierPath(rect: rect).cgPath
            }
        }
        shouldRasterize = true
        rasterizationScale = UIScreen.main.scale
    }
}

稍后我会 post 一些示例，但这对我来说适用于循环视图。

Answer 7

历史上可能有点挖掘，但也许有些人有同样的问题。我使用了已接受答案中的代码示例。但是效果却大不相同： - y 值必须是草图中相同值的一半左右 - 我尝试在导航栏上应用阴影，但效果却大不相同 - 在使用与草图相同的值时几乎看不到。

看来这个方法完全没有反映草图参数。有什么提示吗？

Answer 8

我非常喜欢和评论中的建议。这就是我修改该解决方案的方式：

extension UIView {
  func applyShadow(color: UIColor, alpha: Float, x: CGFloat, y: CGFloat, blur: CGFloat, spread: CGFloat) {
    layer.masksToBounds = false
    layer.shadowColor = color.cgColor
    layer.shadowOpacity = alpha
    layer.shadowOffset = CGSize(width: x, height: y)
    layer.shadowRadius = blur / UIScreen.main.scale
    if spread == 0 {
      layer.shadowPath = nil
    } else {
      let dx = -spread
      let rect = bounds.insetBy(dx: dx, dy: dx)
      layer.shadowPath = UIBezierPath(rect: rect).cgPath
    }
  }
}

用法：

myButton.applyShadow(color: .black, alpha: 0.2, x: 0, y: 1, blur: 2, spread: 0)

Answer 9

在的基础上稍作改动，对我的项目来说效果很好。

支持阴影角半径（对于一些圆角视图）
spread == 0它仍然应用阴影效果（看起来像边框）

struct SketchShadow {
    var color: UIColor = .black
    let alpha: Float = 0.1
    let x: CGFloat
    let y: CGFloat
    let blur: CGFloat
    let spread: CGFloat
    let cornorRadius: CGFloat
    
    func applyToLayer(_ layer: CALayer) {
        layer.masksToBounds = false
        layer.shadowColor = color.cgColor
        layer.shadowOpacity = alpha
        layer.shadowOffset = CGSize(width: x, height: y)
        layer.shadowRadius = blur / 2.0
        if spread == 0 {
            layer.shadowPath = UIBezierPath(roundedRect: layer.bounds, byRoundingCorners: .allCorners, cornerRadii: CGSize(width: cornorRadius, height: cornorRadius)).cgPath
        } else {
            let dx = -(spread)
            let rect = layer.bounds.insetBy(dx: dx, dy: dx)
            layer.shadowPath = UIBezierPath(roundedRect: rect, byRoundingCorners: .allCorners, cornerRadii: CGSize(width: cornorRadius, height: cornorRadius)).cgPath
        }
    }
}

如何控制阴影扩散和模糊？

How to control shadow spread and blur?

core-graphics

uiview

ios

swift