Swift JPEG 是一个跨平台的纯 Swift 框架，用于解码、检查、编辑和编码 JPEG 图像。核心框架没有外部依赖，包括 Foundation，并且应该在所有 Swift 平台上编译并提供一致的行为。该框架在 Linux 和 MacOS 上支持额外的功能，例如文件系统支持。

要将 Swift JPEG 添加到项目中，请将此描述符添加到你的 Package.swift 文件中的 dependencies 列表

.package(url: "https://github.com/kelvin13/jpeg", .exact("1.0.0"))

import JPEG
func decode(jpeg path:String) throws
{
    guard let image:JPEG.Data.Rectangular<JPEG.Common> = try .decompress(path: path)
    else 
    {
        // failed to access file from file system
    }

    let rgb:[JPEG.RGB]      = image.unpack(as: JPEG.RGB.self), 
        size:(x:Int, y:Int) = image.size
    // ...
}

import JPEG
func encode(jpeg path:String, size:(x:Int, y:Int), pixels:[JPEG.RGB], 
    compression:Double) // 0.0 = highest quality
    throws 
{
    let layout:JPEG.Layout<JPEG.Common> = .init(
        format:     .ycc8,
        process:    .baseline, 
        components: 
        [
            1: (factor: (2, 2), qi: 0), // Y
            2: (factor: (1, 1), qi: 1), // Cb
            3: (factor: (1, 1), qi: 1), // Cr 
        ], 
        scans: 
        [
            .sequential((1, \.0, \.0), (2, \.1, \.1), (3, \.1, \.1)),
        ])
    let jfif:JPEG.JFIF = .init(version: .v1_2, density: (72, 72, .inches))
    let image:JPEG.Data.Rectangular<JPEG.Common> = 
        .pack(size: size, layout: layout, metadata: [.jfif(jfif)], pixels: rgb)

    try image.compress(path: path, quanta: 
    [
        0: JPEG.CompressionLevel.luminance(  compression).quanta,
        1: JPEG.CompressionLevel.chrominance(compression).quanta
    ])
}

jpeg

教程和示例程序

api 参考

开始使用

基本用法