如何创建动画GIF [英] How to create an animated GIF

问题描述

我想在SwiftUI中创建动画GIF.

I’d like to create an animated GIF in SwiftUI.

我尝试过:

1. 向我的资产添加GIF并通过Image(myGif)
加载
2. 通过下载GIF图像来创建UIImage，并将其传递给Image
3. 使用该脚本来创建UIImage，然后重复#2.

1. Adding a GIF to my assets and loading that through Image("myGif")
2. Creating a UIImage through downloading a GIF image, and passing that to Image
3. Using this script to create a UIImage and then repeating #2.

以上方法均无效，有人知道吗?

None of the above worked, has anyone figured this out?

推荐答案

您可以通过从UIView创建UIViewRepresentable来实现. UIViewRepresentable为您创建View，您可以在SwiftUI类中使用它.

You can do it by creating UIViewRepresentable from UIView. UIViewRepresentable create View for you, which you can use it in SwiftUI class.

第一步:为Gifview创建UIView类

Step1: Create UIView class for Gifview

class GIFPlayerView: UIView {
    private let imageView = UIImageView()

    convenience init(gifName: String) { 
       self.init()
       let gif = UIImage.gif(asset: gifName)
       imageView.image = gif
       imageView.contentMode = .scaleAspectFit
       self.addSubview(imageView)
    }

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

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override func layoutSubviews() {
        super.layoutSubviews()
        imageView.frame = bounds
    }
}

第二步:为GifView创建UIViewRepresentable类

Step2: Create UIViewRepresentable class for GifView

struct GIFView: UIViewRepresentable {
    var gifName: String

    func updateUIView(_ uiView: UIView, context: UIViewRepresentableContext<GIFView>) {

    }


    func makeUIView(context: Context) -> UIView {
        return GIFPlayerView(gifName: gifName)
    }
}

第3步::使用该UIViewRepresentable视图.

var body: some View {
    VStack {
        GIFView(gifName: "your gif name")
    }
}

注意: Gif到图像的扩展名.请参阅: https://stackoverflow.com/a/45554784

Note: Extension for Gif to Image. Refer: https://stackoverflow.com/a/45554784

extension UIImageView {

    public func loadGif(name: String) {
        DispatchQueue.global().async {
            let image = UIImage.gif(name: name)
            DispatchQueue.main.async {
                self.image = image
            }
        }
    }

    @available(iOS 9.0, *)
    public func loadGif(asset: String) {
        DispatchQueue.global().async {
            let image = UIImage.gif(asset: asset)
            DispatchQueue.main.async {
                self.image = image
            }
        }
    }

}

extension UIImage {

    public class func gif(data: Data) -> UIImage? {
        // Create source from data
        guard let source = CGImageSourceCreateWithData(data as CFData, nil) else {
            print("SwiftGif: Source for the image does not exist")
            return nil
        }

        return UIImage.animatedImageWithSource(source)
    }

    public class func gif(url: String) -> UIImage? {
        // Validate URL
        guard let bundleURL = URL(string: url) else {
            print("SwiftGif: This image named \"\(url)\" does not exist")
            return nil
        }

        // Validate data
        guard let imageData = try? Data(contentsOf: bundleURL) else {
            print("SwiftGif: Cannot turn image named \"\(url)\" into NSData")
            return nil
        }

        return gif(data: imageData)
    }

    public class func gif(name: String) -> UIImage? {
        // Check for existance of gif
        guard let bundleURL = Bundle.main
          .url(forResource: name, withExtension: "gif") else {
            print("SwiftGif: This image named \"\(name)\" does not exist")
            return nil
        }

        // Validate data
        guard let imageData = try? Data(contentsOf: bundleURL) else {
            print("SwiftGif: Cannot turn image named \"\(name)\" into NSData")
            return nil
        }

        return gif(data: imageData)
    }

    @available(iOS 9.0, *)
    public class func gif(asset: String) -> UIImage? {
        // Create source from assets catalog
        guard let dataAsset = NSDataAsset(name: asset) else {
            print("SwiftGif: Cannot turn image named \"\(asset)\" into NSDataAsset")
            return nil
        }

        return gif(data: dataAsset.data)
    }

    internal class func delayForImageAtIndex(_ index: Int, source: CGImageSource!) -> Double {
        var delay = 0.1

        // Get dictionaries
        let cfProperties = CGImageSourceCopyPropertiesAtIndex(source, index, nil)
        let gifPropertiesPointer = UnsafeMutablePointer<UnsafeRawPointer?>.allocate(capacity: 0)
        defer {
            gifPropertiesPointer.deallocate()
        }
        let unsafePointer = Unmanaged.passUnretained(kCGImagePropertyGIFDictionary).toOpaque()
        if CFDictionaryGetValueIfPresent(cfProperties, unsafePointer, gifPropertiesPointer) == false {
            return delay
        }

        let gifProperties: CFDictionary = unsafeBitCast(gifPropertiesPointer.pointee, to: CFDictionary.self)

        // Get delay time
        var delayObject: AnyObject = unsafeBitCast(
            CFDictionaryGetValue(gifProperties,
                Unmanaged.passUnretained(kCGImagePropertyGIFUnclampedDelayTime).toOpaque()),
            to: AnyObject.self)
        if delayObject.doubleValue == 0 {
            delayObject = unsafeBitCast(CFDictionaryGetValue(gifProperties,
                Unmanaged.passUnretained(kCGImagePropertyGIFDelayTime).toOpaque()), to: AnyObject.self)
        }

        if let delayObject = delayObject as? Double, delayObject > 0 {
            delay = delayObject
        } else {
            delay = 0.1 // Make sure they're not too fast
        }

        return delay
    }

    internal class func gcdForPair(_ lhs: Int?, _ rhs: Int?) -> Int {
        var lhs = lhs
        var rhs = rhs
        // Check if one of them is nil
        if rhs == nil || lhs == nil {
            if rhs != nil {
                return rhs!
            } else if lhs != nil {
                return lhs!
            } else {
                return 0
            }
        }

        // Swap for modulo
        if lhs! < rhs! {
            let ctp = lhs
            lhs = rhs
            rhs = ctp
        }

        // Get greatest common divisor
        var rest: Int
        while true {
            rest = lhs! % rhs!

            if rest == 0 {
                return rhs! // Found it
            } else {
                lhs = rhs
                rhs = rest
            }
        }
    }

    internal class func gcdForArray(_ array: [Int]) -> Int {
        if array.isEmpty {
            return 1
        }

        var gcd = array[0]

        for val in array {
            gcd = UIImage.gcdForPair(val, gcd)
        }

        return gcd
    }

    internal class func animatedImageWithSource(_ source: CGImageSource) -> UIImage? {
        let count = CGImageSourceGetCount(source)
        var images = [CGImage]()
        var delays = [Int]()

        // Fill arrays
        for index in 0..<count {
            // Add image
            if let image = CGImageSourceCreateImageAtIndex(source, index, nil) {
                images.append(image)
            }

            // At it's delay in cs
            let delaySeconds = UIImage.delayForImageAtIndex(Int(index),
                source: source)
            delays.append(Int(delaySeconds * 1000.0)) // Seconds to ms
        }

        // Calculate full duration
        let duration: Int = {
            var sum = 0

            for val: Int in delays {
                sum += val
            }

            return sum
            }()

        // Get frames
        let gcd = gcdForArray(delays)
        var frames = [UIImage]()

        var frame: UIImage
        var frameCount: Int
        for index in 0..<count {
            frame = UIImage(cgImage: images[Int(index)])
            frameCount = Int(delays[Int(index)] / gcd)

            for _ in 0..<frameCount {
                frames.append(frame)
            }
        }

        // Heyhey
        let animation = UIImage.animatedImage(with: frames,
            duration: Double(duration) / 1000.0)

        return animation
    }

}

这篇关于如何创建动画GIF的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！