with Glide it is possible to define custom Model Loaders

I bet you usually do

  Glide.with(context)
  .load("https://baseUrl/very/cute/cat.jpg")
  .into(imageView)

Sometimes you need to use an external API in order to get your URL for Glide:

data class ThumbnailRequest( ... )

data class ThumbnailResponse(val height: Int, val width: Int, val url: String)

interface ThumbnailApi{
    suspend fun getThumbnail(request: ThumbnailRequest) : ThumbnailResponse
}

in this case you need to call API first, then use ThumbnailResponse.url to load image with Glide.

This is not the best solution, we can do it better! 🚀

This project demonstrates solution to load your ThumbnailRequest directly to Glide, without overhead around fetching urls somewhere else:

Glide.with(context)
        .load( ThumnbailRequest( ... ) )
        .into(imageView)

🎉 🎉 🎉

This is possible with custom ModelLoader

https://bumptech.github.io/glide/tut/custom-modelloader.html#writing-a-custom-modelloader

This requires a lot of boilerplate code, but I got hands dirty and eased this process as much as possible.

You need to focus on following models:

typealias ThumbnailUseCase = suspend (ThumbnailRequest) -> ThumbnailResponse //your API
typealias RequestType = ThumbnailRequest

Behind the scenes following flow of transformations happens:

(ThumbnailRequest) ==> (ThumbnailResponse) ==> (InputStream == your image)

Do not hesitate to leave a ⭐ if this solution helped you 😃

Enjoy!