MessageKit/Sources/Views/PlayButtonView.swift

// MIT License
//
// Copyright (c) 2017-2019 MessageKit
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

import UIKit

open class PlayButtonView: UIView {
  // MARK: Lifecycle

  // MARK: - Initializers

  public override init(frame: CGRect) {
    super.init(frame: frame)

    setupSubviews()
    setupConstraints()
    setupView()
  }

  required public init?(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)

    setupSubviews()
    setupConstraints()
    setupView()
  }

  // MARK: Open

  // MARK: - Methods

  open override func layoutSubviews() {
    super.layoutSubviews()

    guard !cacheFrame.equalTo(frame) else { return }
    cacheFrame = frame

    updateTriangleConstraints()
    applyCornerRadius()
    applyTriangleMask()
  }

  // MARK: Public

  // MARK: - Properties

  public let blurView = UIVisualEffectView(effect: UIBlurEffect(style: .light))
  public let triangleView = UIView()

  // MARK: Private

  private var triangleCenterXConstraint: NSLayoutConstraint?
  private var cacheFrame: CGRect = .zero

  private func setupSubviews() {
    addSubview(blurView)
    addSubview(triangleView)
  }

  private func setupView() {
    triangleView.clipsToBounds = true
    triangleView.backgroundColor = .black
    blurView.clipsToBounds = true
    backgroundColor = .clear
  }

  private func setupConstraints() {
    triangleView.translatesAutoresizingMaskIntoConstraints = false

    let centerX = triangleView.centerXAnchor.constraint(equalTo: centerXAnchor)
    let centerY = triangleView.centerYAnchor.constraint(equalTo: centerYAnchor)
    let width = triangleView.widthAnchor.constraint(equalTo: widthAnchor, multiplier: 0.5)
    let height = triangleView.heightAnchor.constraint(equalTo: heightAnchor, multiplier: 0.5)

    triangleCenterXConstraint = centerX

    NSLayoutConstraint.activate([centerX, centerY, width, height])

    blurView.translatesAutoresizingMaskIntoConstraints = false
    NSLayoutConstraint.activate([
      blurView.centerXAnchor.constraint(equalTo: centerXAnchor),
      blurView.centerYAnchor.constraint(equalTo: centerYAnchor),
      blurView.heightAnchor.constraint(equalTo: heightAnchor),
      blurView.widthAnchor.constraint(equalTo: widthAnchor),
    ])
  }

  private func triangleMask(for frame: CGRect) -> CAShapeLayer {
    let shapeLayer = CAShapeLayer()
    let trianglePath = UIBezierPath()

    let point1 = CGPoint(x: frame.minX, y: frame.minY)
    let point2 = CGPoint(x: frame.maxX, y: frame.maxY / 2)
    let point3 = CGPoint(x: frame.minX, y: frame.maxY)

    trianglePath.move(to: point1)
    trianglePath.addLine(to: point2)
    trianglePath.addLine(to: point3)
    trianglePath.close()

    shapeLayer.path = trianglePath.cgPath

    return shapeLayer
  }

  private func updateTriangleConstraints() {
    triangleCenterXConstraint?.constant = triangleView.frame.width / 8
  }

  private func applyTriangleMask() {
    let rect = CGRect(origin: .zero, size: triangleView.bounds.size)
    triangleView.layer.mask = triangleMask(for: rect)
  }

  private func applyCornerRadius() {
    blurView.layer.cornerRadius = frame.width / 2
  }
}