iOS - 创建核心图像过滤器循环时保留原始图像

Question

我遵循了这两个教程tutsplus 和appcoda

我在 vc1 中有一个图像，我将其传递给 vc2。 vc2 有两个 imageViews：originalImageView 显示来自 vc1 的原始图像，filteredImageView 显示应用了核心图像过滤器的新图像。 filteredImageView 锚定在 originalImageView 之上

我还有一个滚动视图，我使用 as 按钮创建 coreImage 过滤器，一旦按下按钮，就会应用新过滤器，过滤后的图像现在显示在 filteredImageView 内，它隐藏了 originalImageView，因为它位于它。

一旦用户按下任何包含过滤器的按钮，他们就无法返回到原始图像。

如何创建一个按钮来显示滚动视图中的原始图像以及所有过滤后的图像？理想情况下，它将是第一张图片，这样一旦用户按下它，就会显示原始图片

let originalImageView: UIImageView = {
    let imageView = UIImageView()
    imageView.translatesAutoresizingMaskIntoConstraints = false
    imageView.contentMode = .scaleAspectFill
    return imageView
}()

let filteredImageView: UIImageView = {
    let imageView = UIImageView()
    imageView.translatesAutoresizingMaskIntoConstraints = false
    imageView.contentMode = .scaleAspectFill
    return imageView
}()

let scrollView: UIScrollView = {
    let scrollView = UIScrollView()
    scrollView.translatesAutoresizingMaskIntoConstraints = false
    scrollView.backgroundColor = .black
    return scrollView
}()

var originalImage: UIImage? // set from vc1

let ciFilterNames = [
    "CISharpenLuminance",
    "CIPhotoEffectChrome",
    "CIPhotoEffectFade",
    "CIPhotoEffectInstant",
    "CIPhotoEffectNoir",
    "CIPhotoEffectProcess",
    "CIPhotoEffectTonal",
    "CIPhotoEffectTransfer",
    "CISepiaTone"
]

override func viewDidLoad() {
    super.viewDidLoad()

    createAnchors()

    guard let originalImage = originalImage else { return }

    originaImage.image = originalImage

    var xCoord: CGFloat = 5
    let yCoord: CGFloat = 5
    let buttonWidth:CGFloat = 70
    let buttonHeight: CGFloat = 70
    let gapBetweenButtons: CGFloat = 5

    var itemCount = 0

    for i in 0..<ciFilterNames.count {

        itemCount = i

        let filterButton = UIButton(type: .custom)
        button.frame = CGRect(x: xCoord, y: yCoord, width: buttonWidth, height: buttonHeight)
        filterButton.tag = itemCount
        filterButton.addTarget(self, action: #selector(filterButtonPressed(_:)), for: .touchUpInside)
        filterButton.layer.cornerRadius = 7
        filterButton.clipsToBounds = true

        guard let openGLContext = EAGLContext(api: .openGLES3) else { return }
        let context = CIContext(eaglContext: openGLContext)

        // Create filters for each button
        let coreImage = CIImage(image: originalImage)
        let filter = CIFilter(name: "\(ciFilterNames[i])" )
        filter?.setDefaults()
        filter?.setValue(coreImage, forKey: kCIInputImageKey)

        if ciFilterNames[i] == "CISharpenLuminance" {
            filter?.setValue(0.8, forKey: kCIInputSharpnessKey)
        } else {
            filter?.setValue(1, forKey: kCIInputIntensityKey)
        }

        guard let output = filter?.value(forKey: kCIOutputImageKey) as? CIImage else { return }
        guard let cgimgresult = context.createCGImage(output, from: output.extent) else { return }
        let imageForButton = UIImage(cgImage: cgimgresult)
        filterButton.setBackgroundImage(imageForButton, for: .normal)

        // Add Buttons in the Scroll View
        xCoord += buttonWidth + gapBetweenButtons
        scrollView.addSubview(filterButton)
    }
}

@objc fileprivate func filterButtonPressed(_ sender: UIButton) {

    let button = sender as UIButton

    filteredImageView.image = button.backgroundImage( for: .normal)
}

func createAnchors() {

    view.addSubview(originalImageView)
    view.addSubview(filteredImageView)
    view.addSubview(scrollView)

    originalImageView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
    originalImageView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
    originalImageView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor).isActive = true
    originalImageView.widthAnchor.constraint(equalToConstant: view.frame.width).isActive = true
    originalImageView.heightAnchor.constraint(equalToConstant: view.frame.width).isActive = true

    filteredImageView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor).isActive = true
    filteredImageView.leadingAnchor.constraint(equalTo: originalImageView.leadingAnchor).isActive = true
    filteredImageView.widthAnchor.constraint(equalTo: originalImageView.widthAnchor).isActive = true
    filteredImageView.heightAnchor.constraint(equalTo: originalImageView.heightAnchor).isActive = true

    scrollView.topAnchor.constraint(equalTo: originalImageView.bottomAnchor, constant: 8).isActive = true
    scrollView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
    scrollView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
    scrollView.heightAnchor.constraint(equalToConstant: 80).isActive = true
}

Answer 1

我使用水平collectionView和viewDidLoad而不是scrollView，第一次我将来自vc1的图像添加到[UIImages]的数组中，然后第二次我循环遍历所有ciFilterNames并将它们添加到数组中，就像我添加它们一样到滚动视图。这样做可以让我将原始图像作为第一张图像以及所有过滤后的图像一起放在 collectionVIew 中。我也只需要一个 imageView。

我在 viewDidLoad 里面的 cmets 中添加了这两个步骤

var collectionView: UICollectionView!

let originalImageView: UIImageView = {
    let imageView = UIImageView()
    imageView.translatesAutoresizingMaskIntoConstraints = false
    imageView.contentMode = .scaleAspectFill
    return imageView
}()

var originalImage: UIImage? // set from vc1 or just use your own UIImage(named: "whatever") for this example
var tableData = [UIImage]()
let filterCell = "filterCell"

let ciFilterNames = [
    "CISharpenLuminance",
    "CIPhotoEffectChrome",
    "CIPhotoEffectFade",
    "CIPhotoEffectInstant",
    "CIPhotoEffectNoir",
    "CIPhotoEffectProcess",
    "CIPhotoEffectTonal",
    "CIPhotoEffectTransfer",
    "CISepiaTone"
]

override func viewDidLoad() {
    super.viewDidLoad()

    configureCollectionView()
    createAnchors()

    guard let originalImage = originalImage else { return }

    originaImage.image = originalImage

    // 1. this appends the originalImage as the very first cell
    tableData.append(originaImage)

    guard let openGLContext = EAGLContext(api: .openGLES3) else { return }
    let context = CIContext(eaglContext: openGLContext)

    for i in 0..<ciFilterNames.count {

        let coreImage = CIImage(image: tableData[0])
        let filter = CIFilter(name: "\(ciFilterNames[i])" )
        filter?.setDefaults()
        filter?.setValue(coreImage, forKey: kCIInputImageKey)

        if ciFilterNames[i] == "CISharpenLuminance" {
            filter?.setValue(0.8, forKey: kCIInputSharpnessKey)
        } else if ciFilterNames[i] == "CISepiaTone" {
            filter?.setValue(1, forKey: kCIInputIntensityKey)
        } else {
            filter?.value(forKey: kCIOutputImageKey) as! CIImage
        }

        guard let output = filter?.value(forKey: kCIOutputImageKey) as? CIImage else { return }
        guard let cgimgresult = context.createCGImage(output, from: output.extent) else { return }
        let newImageWithFilterApplied = UIImage(cgImage: cgimgresult)

        // 2. after each loop append the newImageWithFilterApplied to the rest of the cells
        tableData.append(newImageWithFilterApplied)
        collectionView.reloadData()
    }
}

func configureCollectionView() {
    let layout = UICollectionViewFlowLayout()
    layout.sectionInset = UIEdgeInsetsMake(0, 0, 0, 0)
    layout.scrollDirection = .horizontal

    collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
    collectionView.translatesAutoresizingMaskIntoConstraints = false
    collectionView.delegate = self
    collectionView.dataSource = self
    collectionView.alwaysBounceHorizontal = true
    collectionView.backgroundColor = .black
    collectionView.showsHorizontalScrollIndicator = false
    collectionView.register(FilterCell.self, forCellWithReuseIdentifier: filterCell)
}

func createAnchors() {

    view.addSubview(originalImageView)
    view.addSubview(collectionView)

    originalImageView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
    originalImageView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
    originalImageView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor).isActive = true
    originalImageView.heightAnchor.constraint(equalToConstant: view.frame.width).isActive = true

    collectionView.topAnchor.constraint(equalTo: originalImageView.bottomAnchor, constant: 10).isActive = true
    collectionView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
    collectionView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
    collectionView.heightAnchor.constraint(equalToConstant: 80).isActive = true
}

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return tableData.count
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    return CGSize(width: 80, height: 80)
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
    return 10
}

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: filterCell, for: indexPath) as! FilterCell

    cell.imageView.image = tableData[indexPath.item]

    return cell
}

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    guard let cell = collectionView.cellForItem(at: indexPath) as? FilterCell else { return }
    guard let indexPath = collectionView.indexPath(for: cell) else { return }

    originalImageView.image = tableData[indexPath.item]
}