DZShadowsView

DZShadowsView.swift

//
//  DZShadowsView.swift
//
//
//  Created by Nikhil Nigade on 16/12/21.
//

#if !os(watchOS)

#if os(iOS)
import UIKit
#elseif os(macOS)
import AppKit
#endif

import EasyPeasy

#if os(iOS)
public typealias RealColor = UIColor
#else
public typealias RealColor = NSColor
#endif

public final class DZShadowsView: RealView {
  
  #if os(iOS)
  public let contentView: RealView = UIView()
  #else
  public let contentView: RealView = FlippedView()
  #endif
  
  public struct Shadow: Hashable {
    var radius: Double
    var offset: CGSize
    var color: RealColor
    var opacity: Float
    
    /// Create a shadow from params
    /// - Parameters:
    ///   - radius: radius of the shadow. See `sketchShadow` for more info.
    ///   - offset: offset for the shadow
    ///   - color: color of the shadow
    ///   - opacity: opacity of the shadow (don't set on the color)
    ///   - sketchShadow: true if the shadow is being created from Sketch's layer panel. When true, the radius is halved.
    public init(radius: Double, offset: CGSize, color: RealColor, opacity: Float, sketchShadow: Bool = false) {
      self.radius = radius / (sketchShadow ? 2.0 : 1.0)
      self.offset = offset
      self.color = color
      self.opacity = opacity
    }
    
    public func hash(into hasher: inout Hasher) {
      hasher.combine(radius)
      hasher.combine(offset.width)
      hasher.combine(offset.height)
      hasher.combine(opacity)
      hasher.combine(color.description)
    }
  }
  
  /// The shadows to setup on this view.
  public var shadows: [Shadow] = [] {
    didSet {
      if oldValue != shadows {
        setupShadows()
      }
    }
  }
  
  public override init(frame: CGRect) {
    super.init(frame: frame)
    commonInit()
  }
  
  public required init?(coder: NSCoder) {
    super.init(coder: coder)
    commonInit()
  }
  
  private func commonInit() {
    #if os(iOS)
    layer.masksToBounds = false
    contentView.layer.masksToBounds = true
    contentView.backgroundColor = .systemBackground
    #elseif os(macOS)
    contentView.wantsLayer = true
    layer?.masksToBounds = false
    contentView.layer?.masksToBounds = true
    contentView.backgroundColor = .windowBackgroundColor
    #endif
    contentView.translatesAutoresizingMaskIntoConstraints = false
    
    super.addSubview(contentView)
    contentView.easy.layout(Edges())
  }
  
  public override func addSubview(_ aView: RealView) {
    contentView.addSubview(aView)
  }
  
  public func setNeedsUpdateShadows() {
    setupShadows()
    #if os(iOS)
    setNeedsLayout()
    setNeedsDisplay()
    #elseif os(macOS)
    layoutSubtreeIfNeeded()
    setNeedsDisplay(frame)
    #endif
  }
  
  private var layers: [CALayer] = []
  private func setupShadows() {
    for layer in layers {
      layer.removeFromSuperlayer()
    }
    
    for shadow in shadows {
      let sublayer = CALayer()
      sublayer.frame = bounds
      #if os(iOS)
      sublayer.cornerRadius = contentView.layer.cornerRadius
      sublayer.shadowPath = UIBezierPath(roundedRect: bounds, cornerRadius: contentView.layer.cornerRadius).cgPath
      #elseif os(macOS)
      sublayer.cornerRadius = contentView.layer?.cornerRadius ?? 5
      sublayer.shadowPath = NSBezierPath(roundedRect: bounds, xRadius: contentView.layer!.cornerRadius, yRadius: contentView.layer!.cornerRadius).cgPath
      #endif
      sublayer.shadowOpacity = shadow.opacity
      sublayer.shadowColor = shadow.color.cgColor
      sublayer.shadowOffset = shadow.offset
      sublayer.shadowRadius = shadow.radius
      
      #if os(iOS)
      layer.addSublayer(sublayer)
      #elseif os(macOS)
      layer?.addSublayer(sublayer)
      #endif
      layers.append(sublayer)
    }
  }
  #if os(iOS)
  public override func layoutSubviews() {
    backgroundColor = .clear
    
    for sublayer in layer.sublayers ?? [] {
      sublayer.frame = bounds
      sublayer.shadowPath = UIBezierPath(roundedRect: bounds, cornerRadius: contentView.layer.cornerRadius).cgPath
    }
    
    bringSubviewToFront(contentView)
  }
  #elseif os(macOS)
  public override func layout() {
    super.layout()

    backgroundColor = .clear
    contentView.layer!.removeFromSuperlayer()
    
    for sublayer in layer?.sublayers ?? [] {
      sublayer.frame = bounds
      sublayer.shadowPath = NSBezierPath(roundedRect: bounds, xRadius: contentView.layer!.cornerRadius, yRadius: contentView.layer!.cornerRadius).cgPath
    }
    // brings subview to front
    layer?.addSublayer(contentView.layer!)
  }
  #endif
  
}

#if canImport(Cocoa)
public extension NSBezierPath {

  var cgPath: CGPath {
    let path = CGMutablePath()
    var points = [CGPoint](repeating: .zero, count: 3)
    for i in 0 ..< self.elementCount {
      let type = self.element(at: i, associatedPoints: &points)

      switch type {
      case .moveTo:
        path.move(to: points[0])

      case .lineTo:
        path.addLine(to: points[0])

      case .curveTo:
        path.addCurve(to: points[2], control1: points[0], control2: points[1])

      case .closePath:
        path.closeSubpath()

      @unknown default:
        break
      }
    }
    return path
  }
}
#endif