Data fetcher that can be registered with a Glide module to load data from AWS S3 Storage

AwsDataFetcher.kt

class AwsDataFetcher(private val s3Client: AmazonS3Client, private val awsImage: AwsImage) : DataFetcher<InputStream> {

    override fun getDataClass() = InputStream::class.java

    override fun loadData(priority: Priority, callback: DataFetcher.DataCallback<in InputStream>) {
        callback.onDataReady(
            s3Client.getObject(
                GetObjectRequest(
                    awsImage.bucket,
                    awsImage.imageKey
                )
            ).objectContent
        )
    }

    override fun getDataSource() = DataSource.REMOTE

    override fun cleanup() {}
    override fun cancel() {}
}

class AwsImageLoader(private val s3Client: AmazonS3Client) : ModelLoader<AwsImage, InputStream> {

    override fun buildLoadData(
        model: AwsImage,
        width: Int,
        height: Int,
        options: Options
    ): ModelLoader.LoadData<InputStream>? {
        return ModelLoader.LoadData(ObjectKey(model), AwsDataFetcher(s3Client, model))
    }

    override fun handles(model: AwsImage): Boolean {
        return !model.imageKey.isNullOrEmpty()
    }
}

class AwsImageLoaderFactory(private val s3Client: AmazonS3Client) : ModelLoaderFactory<AwsImage, InputStream> {

    override fun build(multiFactory: MultiModelLoaderFactory): ModelLoader<AwsImage, InputStream> {
        return AwsImageLoader(s3Client)
    }

    override fun teardown() {}
}

AwsImage.kt

data class AwsImage(val imageKey: String?, val bucket: String = AWS_S3_BUCKET)

ImageViewExt.kt

/* AWS images */
fun ImageView.loadAwsImage(
    awsImage: AwsImage?,
    thumbnailFactor: Float = SCALE_FACTOR_FULL_SIZE,
    shape: RequestOptions? = null
) =
    Glide.with(context)
        .load(awsImage).apply { shape?.let { apply(it) } }
        .thumbnail(thumbnailFactor)
        .placeholder(R.drawable.placeholder)
        .error(R.drawable.placeholder)
        .into(this)