interface Decoder {// 判断当前解码器是否支持解码指定MIME类型的图片数据fun handles(mimeType: String): Boolean// 执行解码操作，将输入流中的图片数据解码为Drawable对象suspend fun decode(input: InputStream, mimeType: String, options: Options): Drawable
}

class DecoderRegistry {// 存储MIME类型与对应解码器的映射关系private val decoders = mutableMapOf<String, Decoder>()// 注册解码器的方法，将MIME类型与解码器实例关联fun register(mimeType: String, decoder: Decoder) {decoders[mimeType] = decoder}// 根据MIME类型查找对应的解码器fun getDecoder(mimeType: String): Decoder? {return decoders[mimeType]}// 获取所有已注册的解码器fun decoders(): List<Decoder> {return decoders.values.toList()}
}

class ImageLoader {private val decoderRegistry: DecoderRegistrysuspend fun execute(request: ImageRequest): Drawable {// 从数据源获取图片数据（可能来自网络或缓存）val data = fetchData(request)// 根据数据源的MIME类型获取对应的解码器val decoder = getDecoderFor(data, request)// 使用解码器将数据解码为Drawablereturn decoder.decode(data, request.mimeType, request.options)}// 根据数据源和请求信息获取合适的解码器private fun getDecoderFor(data: Any, request: ImageRequest): Decoder {val mimeType = getMimeType(data)// 优先查找与MIME类型精确匹配的解码器val decoder = decoderRegistry.getDecoder(mimeType)if (decoder != null) {return decoder}// 若未找到精确匹配的解码器，则尝试查找通用解码器return findFallbackDecoder(mimeType)}// 查找通用解码器的方法private fun findFallbackDecoder(mimeType: String): Decoder {// 遍历所有已注册的解码器，找到第一个支持该MIME类型的解码器return decoderRegistry.decoders().firstOrNull { it.handles(mimeType) }?: throw IllegalArgumentException("No decoder found for $mimeType")}
}

class CustomDecoder : Decoder {// 判断是否支持解码WebP格式图片override fun handles(mimeType: String): Boolean {return "image/webp" == mimeType}override suspend fun decode(input: InputStream, mimeType: String, options: Options): Drawable {if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {// Android 11及以上版本使用ImageDecoder进行解码val source = ImageDecoder.createSource(input)return ImageDecoder.decodeDrawable(source) { decoder ->// 可根据需求配置解码选项，如采样率等decoder.setTargetSampleSize(1)}} else {// 低版本系统使用BitmapFactory解码为Bitmap后转换为Drawableval bitmap = BitmapFactory.decodeStream(input)return BitmapDrawable(Resources.getSystem(), bitmap)}}
}

val imageLoader = ImageLoader.Builder(context).components {// 获取解码器注册中心实例val decoderRegistry = it.get(DecoderRegistry::class)// 注册自定义解码器，将"image/webp" MIME类型与CustomDecoder关联decoderRegistry.register("image/webp", CustomDecoder())}.build()

interface Transform {// 获取变换操作的唯一标识，用于缓存等场景fun key(): String// 执行变换操作，接收原始Bitmap对象，返回变换后的Bitmapsuspend fun transform(bitmap: Bitmap): Bitmap
}

class Transformer(private val transformations: List<Transform> // 存储多个变换操作的列表
) {// 按顺序执行多个变换操作的方法suspend fun transform(bitmap: Bitmap): Bitmap {var result = bitmapfor (transformation in transformations) {// 依次对Bitmap应用每个变换操作result = transformation.transform(result)}return result}
}

class ImageRequest {private val transformations = mutableListOf<Transform>() // 存储图片变换操作的列表// 添加单个变换操作到请求中的方法fun addTransformation(transformation: Transform): ImageRequest {transformations.add(transformation)return this}// 添加多个变换操作到请求中的方法fun addTransformations(vararg transformations: Transform): ImageRequest {this.transformations.addAll(transformations)return this}// 获取请求中所有变换操作的方法fun transformations(): List<Transform> {return transformations}
}

class WatermarkTransform(private val watermarkBitmap: Bitmap) : Transform {// 获取变换操作的唯一标识，包含水印Bitmap的哈希值override fun key(): String {return "watermark_${watermarkBitmap.hashCode()}"}override suspend fun transform(bitmap: Bitmap): Bitmap {// 创建一个与原始Bitmap相同宽高的新Bitmapval outputBitmap = Bitmap.createBitmap(bitmap.width, bitmap.height, Bitmap.Config.ARGB_8888)val canvas = Canvas(outputBitmap)// 在新Bitmap上绘制原始Bitmapcanvas.drawBitmap(bitmap, 0f, 0f, null)// 在指定位置绘制水印Bitmapcanvas.drawBitmap(watermarkBitmap, (bitmap.width - watermarkBitmap.width).toFloat(), (bitmap.height - watermarkBitmap.height).toFloat(), null)return outputBitmap}
}

val imageLoader = ImageLoader.getInstance(context)
val request = ImageRequest.Builder(context).data("https://example.com/image.jpg")// 添加自定义的水印变换操作.addTransformation(WatermarkTransform(watermarkBitmap)).build()imageLoader.enqueue(request)

// 自定义AVIF解码器
class AvifDecoder : Decoder {override fun handles(mimeType: String): Boolean {return "image/avif" == mimeType}override suspend fun decode(input: InputStream, mimeType: String, options: Options): Drawable {// 实现AVIF解码逻辑，例如使用第三方库// ...}
}// 自定义裁剪变换器
class CropTransform(private val left: Int, private val top: Int, private val width: Int, private val height: Int) : Transform {override fun key(): String {return "crop_$left_$top_$width_$height"}override suspend fun transform(bitmap: Bitmap): Bitmap {return Bitmap.createBitmap(bitmap, left, top, width, height)}
}val imageLoader = ImageLoader.Builder(context).components {val decoderRegistry = it.get(DecoderRegistry::class)// 注册AVIF解码器decoderRegistry.register("image/avif", AvifDecoder())}.build()val request = ImageRequest.Builder(context).data("https://example.com/image.avif")// 添加裁剪变换.addTransformation(CropTransform(10, 10, 200, 200)).build()imageLoader.enqueue(request)

class HighResDecoder : Decoder {override fun handles(mimeType: String): Boolean {return true // 假设支持所有类型，但仅在高分辨率设备使用}override suspend fun decode(input: InputStream, mimeType: String, options: Options): Drawable {// 高分辨率解码逻辑// ...}
}val imageLoader = ImageLoader.Builder(context).components {val decoderRegistry = it.get(DecoderRegistry::class)val metrics = context.resources.displayMetrics// 根据屏幕密度判断是否注册高分辨率解码器if (metrics.densityDpi >= DisplayMetrics.DENSITY_XHIGH) {decoderRegistry.register("high_res", HighResDecoder())}}.build()