在iOS中創建Gif圖像顏色地圖11

Question

我最近在創建Gif時遇到了問題，如果它有太多的顏色丟失。不過感謝來自這裏的幫助，有人能夠幫助我找到解決辦法並創建我自己的色彩地圖。

上的問題在這裏... iOS Colors Incorrect When Saving Animated Gif

這很好工作，直到iOS的11.我找不到更改過的文檔任何東西，將使這個不再工作。我發現的是，如果我刪除kCGImagePropertyGIFImageColorMap gif生成，但它有原始問題，如果gif變得像我以前的問題一樣大，顏色就會丟失。這是有道理的，因爲這是爲了解決這個問題而添加的。

疑似問題...

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: "")! 
} 

這裏是下載一個測試項目的鏈接。注意，如果你在10.3模擬器上運行它，它會很好用，但如果你在iOS 11上運行它，它是一個白色圖像。

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

所引用的其他代碼...

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 
    } 
} 

顏色表

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

這是在IOS 11.0和11.1的一個錯誤。蘋果已經在iOS 11.2+中修復了這個問題

Answer 2

我看到拉鍊項目。它似乎不是 「SWIFTY」 .. :)

總之：

• 下面你可以找到最小的代碼，適用於iOS 11.工作

• ，我們可以從這個

• 的問題開始：

  1）不同尺寸會發生什麼？我們在一個新的大圖像中調整原始圖像周圍的黑色區域的GIF大小

  2）你能給我更多關於彩色地圖的細節嗎？

  3）什麼是矩陣的所有東西？看來你想填黑？這不是聰明和快捷的方法。我將使用Apple功能來放大/填充背景。

我可以幫助你一次您已經好心回答。

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)") 

} 

}