How to load an encrypted image from a URL?

[pspmoe]

The image on the server is encrypted. I need to decrypt the binary data before decoding the image.

Now that I have the function fun ByteArray.decrypted(): ByteArray, how do I apply it to AsycImage?

One way is to make a request in Composable function to get the ByteArray, and then use the decrypted ByteArray as the parameter of AsycImage. But this destroys the caching feature of Coil, which is not what I want.

Platform is Compose Multiplatform (KTOR 3) on JVM

[colinrtwhite]

Your best bet would probably be to extend the image pipeline with a custom Decoder that decrypts the SourceFetchResult, creates a new SourceFetchResult with the decrypted data, then delegates to imageLoader.components.newDecoder(...).first.decode().

[pspmoe]

The issue has been resolved! Here is the code I used, hope it can help more people!

private class CustomDecoder(
    private val result: SourceFetchResult,
    private val options: Options,
    private val imageLoader: ImageLoader
) : Decoder {
    override suspend fun decode(): DecodeResult? {
        val defaultImageLoader = ImageLoader.Builder(options.context).build()
        return defaultImageLoader.components.newDecoder(result, options, imageLoader)?.first?.decode()
    }
}

class CustomDecoderFactory : Decoder.Factory {
    override fun create(
        result: SourceFetchResult,
        options: Options,
        imageLoader: ImageLoader
    ): Decoder {
        val source = result.source
        val buffer = Buffer().apply {
            write(source.source().readByteArray().decryptImage()) // Decrypting ByteArray
        }
        val newSource = ImageSource(buffer, source.fileSystem, source.metadata)
        val newResult = SourceFetchResult(newSource, result.mimeType, result.dataSource)
        return CustomDecoder(newResult, options, imageLoader)
    }
}

@Composable
fun TestWidget() {
    val context = LocalPlatformContext.current
    val imageLoader = remember {
        ImageLoader.Builder(context)
            .components {
                add(NetworkFetcher.Factory(
                    networkClient = { ImageEndpointClient.asNetworkClient() }
                ))
                add(CustomDecoderFactory())
            }
            .build()
    }
    AsyncImage(
        model = "https://example.com/xxx.jpg",
        contentDescription = null,
        imageLoader = imageLoader
    )
}