CGImageDestination 不带属性

Question

我正在使用 swift 目标 Mac OS 导出动画 gif，这有效，但我设置的属性没有被应用。我已经设置了我的属性，当我记录它们时，它们显示如下：

{
HasGlobalColorMap = 1;
LoopCount = 0;
}

在一个循环中，我将每一帧添加到目的地：

CGImageDestinationAddImage(destination, cgGif, gifProperties as CFDictionaryRef)

然后在循环之后我尝试再次设置属性并最终确定目的地：

CGImageDestinationSetProperties(destination, gifProperties as CFDictionaryRef)
            if (!CGImageDestinationFinalize(destination)) {
            NSLog("failed to finalize image destination")
        }

但是生成的图像未设置为循环播放。为什么会这样？

Answer 1

其实，我已经取得了一些进步...

我是这样设置选项的：

        var imageProperties:NSMutableDictionary = NSMutableDictionary()
    imageProperties.setObject(NSNumber(float: 0.1), forKey: kCGImagePropertyGIFDelayTime as NSString)
    imageProperties.setObject(NSNumber(bool: false), forKey: kCGImagePropertyHasAlpha as NSString)
    imageProperties.setObject(NSString(string: "kUTTypeGIF"), forKey: kCGImageSourceTypeIdentifierHint as NSString)
    imageProperties.setObject(NSNumber(bool: false), forKey: kCGImagePropertyGIFImageColorMap as NSString)
    imageProperties.setObject(NSNumber(bool: true), forKey: kCGImageSourceShouldCache as NSString)
    let nestedImageProperties:NSDictionary = [imageProperties: kCGImagePropertyGIFDictionary]
    println("nestedImageProperties: \(nestedImageProperties)")

这是给了我这个结构：

nestedImageProperties: {
    {
    DelayTime = "0.1";
    HasAlpha = 0;
    ImageColorMap = 0;
    kCGImageSourceShouldCache = 1;
    kCGImageSourceTypeIdentifierHint = kUTTypeGIF;
} = "{GIF}";
}

我找到了一个 implementation 定义了这样的属性：

let fileProperties = [kCGImagePropertyGIFDictionary as String: [kCGImagePropertyGIFLoopCount as String: 0]]
let frameProperties = [kCGImagePropertyGIFDictionary as String: [kCGImagePropertyGIFDelayTime as String: 1.0]]

给出这个结构：

Frame Properties: [{GIF}: [DelayTime: 1.0]]
File Properties: [{GIF}: [LoopCount: 0]]

然后我将 fileProperties 应用到目的地：

CGImageDestinationSetProperties(destination, fileProperties as CFDictionaryRef)

以及添加到每个图像的 frameProperties：

CGImageDestinationAddImage(destination, imageRef, frameProperties as CFDictionaryRef)

最后，它正在运行，它们正在被应用。

还没有尝试过多个属性，但应该没问题。

CGImageDestination 不带属性

CGImageDestination not taking properties

cgimage

cgimagesource

cgimageref

swift