在iOS中创建Gif图像颜色地图11

Question

我最近在创建Gif时遇到了问题，如果它有太多的颜色丢失。不过感谢来自这里的帮助，有人能够帮助我找到解决办法并创建我自己的色彩地图。

上的问题在这里... iOS Colors Incorrect When Saving Animated Gif

这很好工作，直到iOS的11.我找不到更改过的文档任何东西，将使这个不再工作。我发现的是，如果我删除kCGImagePropertyGIFImageColorMap gif生成，但它有原始问题，如果gif变得像我以前的问题一样大，颜色就会丢失。这是有道理的，因为这是为了解决这个问题而添加的。

疑似问题...

func createGifFromImage(_ image: UIImage) -> URL{ 

    let fileProperties: [CFString: CFDictionary] = [kCGImagePropertyGIFDictionary: [ 
     kCGImagePropertyGIFHasGlobalColorMap: false as NSNumber] as CFDictionary] 

    let documentsDirectoryPath = "file://\(NSTemporaryDirectory())" 

    if let documentsDirectoryURL = URL(string: documentsDirectoryPath){ 

     let fileURL = documentsDirectoryURL.appendingPathComponent("test.gif") 
     let destination = CGImageDestinationCreateWithURL(fileURL as CFURL, kUTTypeGIF, 1, nil)! 

     CGImageDestinationSetProperties(destination, fileProperties as CFDictionary); 

     let colorMap = image.getColorMap() 
     print("ColorMap \(colorMap.exported as NSData)") 

     let frameProperties: [String: AnyObject] = [ 
      String(kCGImagePropertyGIFImageColorMap): colorMap.exported as NSData 
     ] 

     let properties: [String: AnyObject] = [ 
      String(kCGImagePropertyGIFDictionary): frameProperties as AnyObject 
     ] 

     CGImageDestinationAddImage(destination, image.cgImage!, properties as CFDictionary); 

     if (!CGImageDestinationFinalize(destination)) { 
      print("failed to finalize image destination") 
     } 

     return fileURL 
    } 

    //shouldn't get here 
    return URL(string: "")! 
} 

这里是下载一个测试项目的链接。注意，如果你在10.3模拟器上运行它，它会很好用，但如果你在iOS 11上运行它，它是一个白色图像。

https://www.dropbox.com/s/hdmkwyz47ondd52/gifTest2.zip?dl=0

所引用的其他代码...

extension UIImage{ 
    //MARK: - Pixel 
    func getColorMap() -> ColorMap { 

     var colorMap = ColorMap() 

     let pixelData = self.cgImage!.dataProvider!.data 
     let data: UnsafePointer<UInt8> = CFDataGetBytePtr(pixelData) 

     var byteIndex = 0 

     for _ in 0 ..< Int(size.height){ 
      for _ in 0 ..< Int(size.width){ 

       let color = Color(red: data[byteIndex], green: data[byteIndex + 1], blue: data[byteIndex + 2]) 
       colorMap.colors.insert(color) 
       byteIndex += 4 
      } 
     } 

     return colorMap 
    } 
} 

颜色表

struct Color : Hashable { 
    let red: UInt8 
    let green: UInt8 
    let blue: UInt8 

    var hashValue: Int { 
     return Int(red) + Int(green) + Int(blue) 
    } 

    public static func == (lhs: Color, rhs: Color) -> Bool { 
     return [lhs.red, lhs.green, lhs.blue] == [rhs.red, rhs.green, rhs.blue] 
    } 
} 


struct ColorMap { 
    var colors = Set<Color>() 

    var exported: Data { 
     let data = Array(colors) 
      .map { [$0.red, $0.green, $0.blue] } 
      .joined() 

     return Data(bytes: Array(data)) 
    } 
} 

Answer 1

这是在IOS 11.0和11.1的一个错误。苹果已经在iOS 11.2+中修复了这个问题

Answer 2

我看到拉链项目。它似乎不是 “SWIFTY” .. :)

总之：

• 下面你可以找到最小的代码，适用于iOS 11.工作

• ，我们可以从这个

• 的问题开始：

  1）不同尺寸会发生什么？我们在一个新的大图像中调整原始图像周围的黑色区域的GIF大小

  2）你能给我更多关于彩色地图的细节吗？

  3）什么是矩阵的所有东西？看来你想填黑？这不是聪明和快捷的方法。我将使用Apple功能来放大/填充背景。

我可以帮助你一次您已经好心回答。

class ViewController: UIViewController { 

override func viewDidLoad() { 
    super.viewDidLoad() 
    // Do any additional setup after loading the view, typically from a nib. 

    if let image = UIImage(named: "image1"){ 
     createGIFFrom(image: image) 
    } 
} 

final func localPath()->URL{ 
    let tempPath = NSTemporaryDirectory() 
    let url = URL.init(fileURLWithPath: tempPath) 
    return url.appendingPathComponent("test.gif") 
} 


private final func createGIFFrom(image: UIImage){ 
    let fileURL = self.localPath() 
    let type: CFString = kUTTypeGIF// kUTTypePNG 
    // from apple code: 
    //https://developer.apple.com/library/content/technotes/tn2313/_index.html 

    guard let myImageDest = CGImageDestinationCreateWithURL(fileURL as CFURL, type, 1, nil) else{ 
     return 
    } 

    guard let imageRef = image.cgImage else{ 
     return 
    } 

    // Add an image to the image destination 
    CGImageDestinationAddImage(myImageDest, imageRef, nil) 
    CGImageDestinationFinalize(myImageDest) 

    print("open image at: \(fileURL)") 

} 

}