CoreGraphic框架解析 (二十七) —— 以高效的方式绘制图案(二)

版本记录

版本号 时间
V1.0 2021.05.30 星期日

前言

quartz是一个通用的术语,用于描述在iOSMAC OS X 中整个媒体层用到的多种技术 包括图形、动画、音频、适配。Quart 2D 是一组二维绘图和渲染APICore Graphic会使用到这组APIQuartz Core专指Core Animation用到的动画相关的库、API和类。CoreGraphicsUIKit下的主要绘图系统,频繁的用于绘制自定义视图。Core Graphics是高度集成于UIView和其他UIKit部分的。Core Graphics数据结构和函数可以通过前缀CG来识别。在app中很多时候绘图等操作我们要利用CoreGraphic框架,它能绘制字符串、图形、渐变色等等,是一个很强大的工具。感兴趣的可以看我另外几篇。
1. CoreGraphic框架解析(一)—— 基本概览
2. CoreGraphic框架解析(二)—— 基本使用
3. CoreGraphic框架解析(三)—— 类波浪线的实现
4. CoreGraphic框架解析(四)—— 基本架构补充
5. CoreGraphic框架解析 (五)—— 基于CoreGraphic的一个简单绘制示例 (一)
6. CoreGraphic框架解析 (六)—— 基于CoreGraphic的一个简单绘制示例 (二)
7. CoreGraphic框架解析 (七)—— 基于CoreGraphic的一个简单绘制示例 (三)
8. CoreGraphic框架解析 (八)—— 基于CoreGraphic的一个简单绘制示例 (四)
9. CoreGraphic框架解析 (九)—— 一个简单小游戏 (一)
10. CoreGraphic框架解析 (十)—— 一个简单小游戏 (二)
11. CoreGraphic框架解析 (十一)—— 一个简单小游戏 (三)
12. CoreGraphic框架解析 (十二)—— Shadows 和 Gloss (一)
13. CoreGraphic框架解析 (十三)—— Shadows 和 Gloss (二)
14. CoreGraphic框架解析 (十四)—— Arcs 和 Paths (一)
15. CoreGraphic框架解析 (十五)—— Arcs 和 Paths (二)
16. CoreGraphic框架解析 (十六)—— Lines, Rectangles 和 Gradients (一)
17. CoreGraphic框架解析 (十七)—— Lines, Rectangles 和 Gradients (二)
18. CoreGraphic框架解析 (十八) —— 如何制作Glossy效果的按钮(一)
19. CoreGraphic框架解析 (十九) —— 如何制作Glossy效果的按钮(二)
20. CoreGraphic框架解析 (二十) —— Curves and Layers(一)
21. CoreGraphic框架解析 (二十一) —— Curves and Layers(二)
22. CoreGraphic框架解析 (二十二) —— Gradients 和 Contexts的简单示例(一)
23. CoreGraphic框架解析 (二十三) —— Gradients 和 Contexts的简单示例(二)
24. CoreGraphic框架解析 (二十四) —— 基于Core Graphic的重复图案的绘制(一)
25. CoreGraphic框架解析 (二十五) —— 基于Core Graphic的重复图案的绘制(二)
26. CoreGraphic框架解析 (二十六) —— 以高效的方式绘制图案(一)

源码

1. Swift

首先看下工程组织结构:

下面就是正文啦。

1. AppDelegate.swift
import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate { }
2. SceneDelegate.swift
import UIKit

class SceneDelegate: UIResponder, UIWindowSceneDelegate {
  var window: UIWindow?
}
3. Game.swift
import UIKit

class Game {
  // MARK: - Properties
  let maxAttemptsAllowed = 5
  let colorSelections: [UIColor] = [.blue, .red, .magenta]
  let totalPatternCount: Int

  var score: Int
  var attempt: Int
  var answers: [PatternView.PatternDirection]

  private var majorityPatternCount: Int {
    return totalPatternCount / 2 + 1
  }

  // MARK: - Object Lifecycle
  init(patternCount count: Int) {
    totalPatternCount = count
    score = 0
    attempt = 0
    answers = []
  }

  // MARK: - Gameplay
  func play(_ guess: PatternView.PatternDirection) -> (correct: Bool, score: Int)? {
    if done() {
      return nil
    }
    if guess == answers[attempt] {
      score += 1
      attempt += 1
      return (true, score)
    } else {
      attempt += 1
      return (false, score)
    }
  }

  func setupNextPlay() -> (directions: [PatternView.PatternDirection], colors: [UIColor]) {
    var directions: [PatternView.PatternDirection] = []
    var colors: [UIColor] = []

    // Get a list of directions that don't belong to the correct answer
    let wrongDirections = PatternView.PatternDirection.allCases.filter {
      $0 != answers[attempt]
    }
    // Get a random number of correct answers to fill, to maintain the majority
    let numberOfCorrectPatterns = Int.random(in: majorityPatternCount ..< totalPatternCount)

    // Fill out the return info
    for index in 0..<totalPatternCount {
      // Front load with the correct answer
      if index < numberOfCorrectPatterns {
        directions.append(answers[attempt])
      } else {
        // Next, randomly assign wrong answers
        if let randomDirection = wrongDirections.randomElement() {
          directions.append(randomDirection)
        }
      }
      // Pick a random color for the pattern
      if let randomColor = colorSelections.randomElement() {
        colors.append(randomColor)
      }
    }
    // Randomly reorder the directions
    directions.shuffle()

    return (directions, colors)
  }

  func done() -> Bool {
    return attempt >= maxAttemptsAllowed
  }

  func reset() {
    score = 0
    attempt = 0
    answers.removeAll()

    generatePlays()
  }
}

// MARK: - Private methods
private extension Game {
  func generatePlays() {
    // Pick the random direction that will be the dominant one
    let allPatternDirections = PatternView.PatternDirection.allCases
    answers = (0..<maxAttemptsAllowed).map { _ in
      // swiftlint:disable:next force_unwrapping
      allPatternDirections.randomElement()!
    }
  }
}
4. GameViewController.swift
import UIKit

class GameViewController: UIViewController {
  // MARK: - Outlets
  @IBOutlet weak var scoreLabel: UILabel!

  @IBOutlet weak var item1PatternView: PatternView!
  @IBOutlet weak var item2PatternView: PatternView!
  @IBOutlet weak var item3PatternView: PatternView!
  @IBOutlet weak var item4PatternView: PatternView!

  @IBOutlet weak var leftButton: UIButton!
  @IBOutlet weak var topButton: UIButton!
  @IBOutlet weak var bottomButton: UIButton!
  @IBOutlet weak var rightButton: UIButton!

  @IBOutlet weak var choiceFeedbackLabel: UILabel!

  // MARK: - Properties
  let numberOfPatterns = 4
  var game: Game?
  var score: Int? {
    didSet {
      if let score = score, let game = game {
        scoreLabel.text = "\(score) / \(game.maxAttemptsAllowed)"
      }
    }
  }

  // MARK: - View Lifecycle
  override func viewDidLoad() {
    super.viewDidLoad()
    game = Game(patternCount: numberOfPatterns)
  }

  override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    game?.reset()
    score = game?.score
  }

  override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)
    showNextPlay()
  }

  override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "resultSegue" {
      if let destinationViewController = segue.destination as? ResultViewController {
        destinationViewController.score = score
      }
    }
  }

  // MARK: - Actions
  @IBAction func choiceButtonPressed(_ sender: UIButton) {
    switch sender {
    case leftButton:
      play(.left)
    case topButton:
      play(.top)
    case bottomButton:
      play(.bottom)
    case rightButton:
      play(.right)
    default:
      play(.left)
    }
  }
}

// MARK: - Private methods
private extension GameViewController {
  func showNextPlay() {
    guard let game = game else { return }
    // Check if the game is still in progress
    if !game.done() {
      // Get the next set of directions and colors for the pattern views
      let (directions, colors) = game.setupNextPlay()
      // Update the pattern views
      setupPatternView(item1PatternView, towards: directions[0], havingColor: colors[0])
      setupPatternView(item2PatternView, towards: directions[1], havingColor: colors[1])
      setupPatternView(item3PatternView, towards: directions[2], havingColor: colors[2])
      setupPatternView(item4PatternView, towards: directions[3], havingColor: colors[3])
      // Re-enable the buttons and hide the answer feedback
      controlsEnabled(true)
    }
  }

  // swiftlint:disable:next identifier_name
  func controlsEnabled(_ on: Bool) {
    // Enable or disable the buttons
    leftButton.isEnabled = on
    topButton.isEnabled = on
    bottomButton.isEnabled = on
    rightButton.isEnabled = on
    // Show or hide the feedback on the answer
    choiceFeedbackLabel.isHidden = on
  }

  // Sets up the pattern view given a diretion and color
  func setupPatternView(
    _ patternView: PatternView,
    towards: PatternView.PatternDirection,
    havingColor color: UIColor
  ) {
    patternView.direction = towards
    patternView.fillColor = color.rgba
    patternView.setNeedsDisplay()
  }

  // Displays the results of the choice
  func displayResults(_ correct: Bool) {
    if correct {
      print("You answered correctly!")
      choiceFeedbackLabel.text = "\u{2713}" // checkmark
      choiceFeedbackLabel.textColor = .green
    } else {
      print("That one got you.")
      choiceFeedbackLabel.text = "\u{2718}" // wrong (X)
      choiceFeedbackLabel.textColor = .red
    }
    // Visual indicator of correctness
    UIView.animate(withDuration: 0.5) {
      self.choiceFeedbackLabel.transform = CGAffineTransform(scaleX: 1.8, y: 1.8)
    } completion: { _ in
      UIView.animate(withDuration: 0.5) {
        self.choiceFeedbackLabel.transform = CGAffineTransform(scaleX: 1.0, y: 1.0)
      }
    }
  }

  // Processes the play and displays the result
  func play(_ selection: PatternView.PatternDirection) {
    // Temporarily disable the buttons and make the feedback label visible
    controlsEnabled(false)
    // Check if the answer is correct
    if let result = game?.play(selection) {
      // Update the score
      score = result.score
      // Show whether the answer is correct or not
      displayResults(result.correct)
    }
    // Wait a little before showing the next play or transition to the
    // end game view
    DispatchQueue.main.asyncAfter(deadline: .now() + 2) { [weak self] in
      guard let self = self else { return }
      if self.game?.done() == true {
        self.performSegue(withIdentifier: "resultSegue", sender: nil)
      } else {
        self.showNextPlay()
      }
    }
  }
}

// MARK: - UIColor extension
extension UIColor {
  // Returns an array that splits out the RGB and Alpha values
  var rgba: [CGFloat] {
    var red: CGFloat = 0
    var green: CGFloat = 0
    var blue: CGFloat = 0
    var alpha: CGFloat = 0
    getRed(&red, green: &green, blue: &blue, alpha: &alpha)
    return [red, green, blue, alpha]
  }
}
5. PatternView.swift
import UIKit

class PatternView: UIView {
  var fillColor: [CGFloat] = [1.0, 0.0, 0.0, 1.0]
  var direction: PatternDirection = .top

  enum Constants {
    static let patternSize: CGFloat = 30.0
    static let patternRepeatCount: CGFloat = 2
  }

  enum PatternDirection: CaseIterable {
    case left
    case top
    case right
    case bottom
  }

  let drawTriangle: CGPatternDrawPatternCallback = { _, context in
    let trianglePath = CGPath.triangle(in:
      CGRect(
        x: 0,
        y: 0,
        width: Constants.patternSize,
        height: Constants.patternSize))
    context.addPath(trianglePath)
    context.fillPath()
  }

  init(fillColor: [CGFloat], direction: PatternDirection = .top) {
    self.fillColor = fillColor
    self.direction = direction
    super.init(frame: CGRect.zero)
  }

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

  override func draw(_ rect: CGRect) {
    // 1
    guard let context = UIGraphicsGetCurrentContext()
    else { return }
    // 2
    UIColor.white.setFill()

    // 3
    context.fill(rect)
    var callbacks = CGPatternCallbacks(
      version: 0,
      drawPattern: drawTriangle,
      releaseInfo: nil)

    // 1
    let patternStepX = rect.width / Constants.patternRepeatCount
    let patternStepY = rect.height / Constants.patternRepeatCount
    // 2
    let patternOffsetX = (patternStepX - Constants.patternSize) / 2.0
    let patternOffsetY = (patternStepY - Constants.patternSize) / 2.0
    // 3
    // 1
    var transform: CGAffineTransform
    // 2
    switch direction {
    case .top:
      transform = .identity
    case .right:
      transform = CGAffineTransform(rotationAngle: 0.5 * .pi)
    case .bottom:
      transform = CGAffineTransform(rotationAngle: .pi)
    case .left:
      transform = CGAffineTransform(rotationAngle: 1.5 * .pi)
    }
    // 3
    transform = transform.translatedBy(x: patternOffsetX, y: patternOffsetY)

    // 4
    guard let pattern = CGPattern(
      info: nil,
      bounds: CGRect(
        x: 0,
        y: 0,
        width: Constants.patternSize,
        height: Constants.patternSize
      ),
      matrix: transform,
      xStep: patternStepX,
      yStep: patternStepY,
      tiling: .constantSpacing,
      isColored: false,
      callbacks: &callbacks)
    else { return }

    // 1
    let baseSpace = CGColorSpaceCreateDeviceRGB()
    guard let patternSpace = CGColorSpace(patternBaseSpace: baseSpace)
    else { return }
    // 2
    context.setFillColorSpace(patternSpace)
    context.setFillPattern(pattern, colorComponents: fillColor)
    context.fill(rect)
  }
}

extension CGPath {
  // 1
  static func triangle(in rect: CGRect) -> CGPath {
    let path = CGMutablePath()
    // 2
    let top = CGPoint(x: rect.width / 2, y: 0)
    let bottomLeft = CGPoint(x: 0, y: rect.height)
    let bottomRight = CGPoint(x: rect.width, y: rect.height)
    // 3
    path.addLines(between: [top, bottomLeft, bottomRight])
    // 4
    path.closeSubpath()
    return path
  }
}
6. ResultViewController.swift
import UIKit

class ResultViewController: UIViewController {
  // MARK: - Outlets
  @IBOutlet weak var scoreLabel: UILabel!

  // MARK: - Properties
  var score: Int?

  // MARK: - View Life Cycle
  override func viewDidLoad() {
    super.viewDidLoad()
    if let score = score {
      scoreLabel.text = "Your final score: \(score)"
    }
  }

  // MARK: - Actions
  @IBAction func playAgainPressed(_ sender: Any) {
    presentingViewController?.dismiss(animated: true, completion: nil)
  }
}

后记

本篇主要讲述了以高效的方式绘制图案,感兴趣的给个赞或者关注~~~

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