如何在 swift 中使用 kingFisher 库中的 AspectScaledToFitAndCenterSizeFilter

Question

在我的项目中，我在 swift 中使用了 AlamofireImage。现在我们用 KingFisher 库替换了 AlamofireImage。我已经使用下面创建了一个结构来适应过滤器

struct AspectScaledToFitAndCenterSizeFilter: ImageFilter, Sizable {
    /// The size of the filter.
    let size: CGSize

    /// Initializes the `AspectScaledToFitSizeFilter` instance with the given size.
    ///
    /// - parameter size: The size.
    ///
    /// - returns: The new `AspectScaledToFitSizeFilter` instance.
    init(size: CGSize) {
        self.size = size
    }

    /// The filter closure used to create the modified representation of the given image.
    var filter: (UIImage) -> UIImage {
        { image in
            image.imageAspectScaledAndCenter(toFit: self.size)
        }
    }
} 

当我们使用 AlmofireImage 时，使用下面的代码来设置图片 url

imageView.af.setImage(withURL: imageURL.mediaURL(), placeholderImage: #imageLiteral(resourceName: "icMissingEntreeGrid"), filter: AspectScaledToFitAndCenterSizeFilter(size: imageSize))

现在我将代码替换为

imageView.kf.setImage(with: imageURL.mediaURL(), placeholder:  imageLiteral(resourceName: "icMissingEntreeGrid"))

但是如何使用 KingFisher 库添加“AspectScaledToFitAndCenterSizeFilter(size: imageSize)”。任何人都可以在这里帮助我。提前致谢。

Answer 1

要创建 Kingfisher 图像处理器，您需要实现 ImageProcessor 协议：

class AspectScaledToFitAndCenterSizeFilter: ImageProcessor {
    /// Identifier of the processor.
    /// - Note: See documentation of `ImageProcessor` protocol for more.
    let identifier: String

    /// The size of the filter.
    let size: CGSize

    /// Initializes the `AspectScaledToFitSizeFilter` instance with the given size.
    ///
    /// - parameter size: The size.
    ///
    /// - returns: The new `AspectScaledToFitSizeFilter` instance.
    init(size: CGSize) {
        self.size = size
        identifier = "com.package.AspectScaledToFitAndCenterSizeFilter(\(size))"
    }

    func process(item: ImageProcessItem, options: KingfisherParsedOptionsInfo) -> KFCrossPlatformImage? {
        switch item {
        case .image(let image):
            return image.imageAspectScaledAndCenter(toFit: self.size)
        case .data:
            return (DefaultImageProcessor.default |> self).process(item: item, options: options)
        }
    }
}

用法：

imageView.kf.setImage(
    with: imageURL.mediaURL(),
    placeholder: #imageLiteral(resourceName: "icMissingEntreeGrid"),
    options: [
        .processor(AspectScaledToFitAndCenterSizeFilter(size: .zero))
    ]
)

在documentation 中查看更多处理器使用情况。