Call existing Fetcher from a custom Fetcher

[Artem Chepurnyi]

Is your feature request related to a problem? Please describe.

   HTTP request             HTTP request
X ------------> String ------------> Image

The current architecture with Mappers and Fetchers does not give me enough flexibility. It seems like the only option here is to create a custom Fetcher that duplicates the functionality of the internal HttpUriFetcher and also does the first data conversion request too.

[Colin White]

It's already possible to call an existing fetcher using an ImageLoader's ComponentRegistry in Coil 2.x. E.g.:

class CustomFetcher(data: Uri, options: Options, imageLoader: ImageLoader) {

    override suspend fun fetch(): FetchResult? {
        // Pass 1 to skip our custom fetcher.
        val (fetcher) = imageLoader.components.newFetcher(data, options, imageLoader, startIndex = 1)
        val result = fetcher.fetch()
        return result
    }

    class Factory : Fetcher.Factory<Uri> {

        override fun create(data: Uri, options: Options, imageLoader: ImageLoader): Fetcher? {
            if (data.scheme != "http" && data.scheme != "https") return null
            return CustomFetcher(data, options, imageLoader)
        }
    }
}