Network Images¶

By default, Coil 3.x does not include support for loading images from the network. This is to avoid forcing a large networking dependency on users who want to use their own networking solution or do not need network URL support (e.g. only loading images from disk).

To add support for fetching images from the network import only one of the following:

implementation("io.coil-kt.coil3:coil-network-okhttp:3.0.4") // Only available on Android/JVM.
implementation("io.coil-kt.coil3:coil-network-ktor2:3.0.4")
implementation("io.coil-kt.coil3:coil-network-ktor3:3.0.4")

If you use OkHttp, that's it. Once imported, network URLs like https://example.com/image.jpg will automatically be supported. If you use Ktor, you need to add supported engines for each platform (see below).

Ktor network engines¶

If you depend on coil-network-ktor2 or coil-network-ktor3 you need to import a Ktor engine for each platform (except Javascript). Here's a quickstart set of engines:

androidMain {
    dependencies {
        implementation("io.ktor:ktor-client-android:<ktor-version>")
    }
}
appleMain {
    dependencies {
        implementation("io.ktor:ktor-client-darwin:<ktor-version>")
    }
}
jvmMain {
    dependencies {
        implementation("io.ktor:ktor-client-java:<ktor-version>")
    }
}

If you want to use a custom networking library, you can import io.coil-kt.coil3:coil-network-core, implement NetworkClient, and register NetworkFetcher with your custom NetworkClient in your ImageLoader.

Using a custom OkHttpClient¶

If you use io.coil-kt.coil3:coil-network-okhttp You can specify a custom OkHttpClient when creating your ImageLoader:

val imageLoader = ImageLoader.Builder(context)
    .components {
        add(
            OkHttpNetworkFetcherFactory(
                callFactory = {
                    OkHttpClient()
                }
            )
        )
    }
    .build()

Note

If you already have a built OkHttpClient, use newBuilder() to build a new client that shares resources with the original.

Cache-Control support¶

By default, Coil 3.x does not respect Cache-Control headers and always saves a response to its disk cache.

io.coil-kt.coil3:coil-network-cache-control includes a CacheStrategy implementation that ensures that NetworkFetcher respects a network response's Cache-Control header.

Pass CacheControlCacheStrategy to your NetworkFetcher then register the custom NetworkFetcher in your ImageLoader:

OkHttpNetworkFetcherFactory(
    cacheStrategy = { CacheControlCacheStrategy() },
)

Note

You need to enable coreLibraryDesugaring to support Android API level 25 or below. Follow the docs here to enable it.

Headers¶

Headers can be added to your image requests in one of two ways. You can set headers for a single request:

val headers = NetworkHeaders.Builder()
    .set("Cache-Control", "no-cache")
    .build()
val request = ImageRequest.Builder(context)
    .data("https://example.com/image.jpg")
    .httpHeaders(headers)
    .target(imageView)
    .build()
imageLoader.execute(request)

Or you can create an OkHttp Interceptor that sets headers for every request executed by your ImageLoader:

class RequestHeaderInterceptor(
    private val name: String,
    private val value: String,
) : Interceptor {

    override fun intercept(chain: Interceptor.Chain): Response {
        val headers = Headers.Builder()
            .set("Cache-Control", "no-cache")
            .build()
        val request = chain.request().newBuilder()
            .headers(headers)
            .build()
        return chain.proceed(request)
    }
}

val imageLoader = ImageLoader.Builder(context)
    .okHttpClient {
        OkHttpClient.Builder()
            // This header will be added to every image request.
            .addNetworkInterceptor(RequestHeaderInterceptor("Cache-Control", "no-cache"))
            .build()
    }
    .build()