fetcher.md

Fetcher

Translations: 简体中文

Fetcher is used to get data from uri, return FetchResult, and hand it over to Decoder for use.

Each uri supported by Sketch has a corresponding Fetcher implementation, as shown in the following table:

URI	Fetcher	Create	Dependent modules	Android	iOS	Desktop	Web
http://, https://	HttpUriFetcher	-	-	✅	✅	✅	✅
file://, /	FileUriFetcher	newFileUri()	-	✅	✅	✅	✅
compose.resource://	ComposeResourceUriFetcher	newComposeResourceUri()	sketch-compose-resources	✅	✅	✅	✅
data:image/, data:img/	Base64UriFetcher	newBase64Uri()	-	✅	✅	✅	✅
asset://	AssetUriFetcher	newAssetUri()	-	✅	❌	❌	❌
content://	ContentUriFetcher	-	-	✅	❌	❌	❌
android.resource://	ResourceUriFetcher	newResourceUri()	-	✅	❌	❌	❌
app.icon://	AppIconUriFetcher	newAppIconUri()	sketch-extensions-core	✅	❌	❌	❌
kotlin.resource://	KotlinResourceUriFetcher	newKotlinResourceUri()	-	❌	✅	✅	❌

• AssetUriFetcher is used to load images from the Android assets directory
• ContentUriFetcher ContentResolver for Android to load images
• ResourceUriFetcher is used to load images from Android's resources directory
• AppIconUriFetcher is used to load the icon of the installed App. It also needs to rely on sketch-extensions-core module. Learn more
• Base64UriFetcher is used to load images from the base64 data block of the uri itself
• ComposeResourceUriFetcher is used to load images from the composeResources directory of Compose Multiplatform, it also needs to depend on the sketch-compose-resources module.
• KotlinResourceUriFetcher is used to load images from the resources directory of kotlin

Register Fetcher

Fetcher that needs to rely on a separate module (such as ComposeResourceUriFetcher) needs to be registered when initializing Sketch, as follows:

// Register for all ImageRequests when customizing Sketch
Sketch.Builder(context).apply {
    components {
        addFetcher(ComposeResourceUriFetcher.Factory())
    }
}.build()

// Register for a single ImageRequest when loading an image
ImageRequest(context, "https://www.example.com/image.gif") {
    components {
        addFetcher(ComposeResourceUriFetcher.Factory())
    }
}

Extend Fetcher

First implement the Fetcher interface to define your Fetcher and its Factory, and then register it through the addFetcher() method, as follows:

class MyFetcher : Fetcher {

    override suspend fun fetch(): Result<FetchResult> {
        // Parse your uri here and get the data
    }

    companion object {
        const val MY_SCHEME = "myUri"
    }

    class Factory : Fetcher.Factory {

        override fun create(sketch: Sketch, request: ImageRequest): MyFetcher? {
            return if (request.uri.startWith("$MY_SCHEME://")) {
                MyFetcher()
            } else {
                null
            }
        }
    }
}

// Register for all ImageRequests when customizing Sketch
Sketch.Builder(context).apply {
    components {
        addFetcher(MyFetcher.Factory())
    }
}.build()

// Register for a single ImageRequest when loading an image
ImageRequest(context, "myUri://sample.jpeg") {
    components {
        addFetcher(MyFetcher.Factory())
    }
}