Interceptor

Translations: 简体中文

Sketch uses Interceptor to handle the execution process of ImageRequest. You can use Interceptor to change the input and output of any link in the execution process.

Interceptor provided by Sketch core module:

• MemoryCacheInterceptor: Provide memory caching function to avoid repeated parsing and image transformation and improve performance.
• PlaceholderInterceptor: Provide placeholder image function, display placeholder image during image loading process
• ResultCacheInterceptor: Provides result caching function to avoid repeated image transformation and improve performance
• ThumbnailInterceptor: Provides a thumbnail function. The thumbnail is loaded at the same time as the original image. The thumbnail is displayed first. After the original image is loaded, the thumbnail display is replaced to improve the user experience.
• TransformationInterceptor: Provides transformation function. After the image is loaded, the image can be transformed, such as circular, rounded, blurred, etc.
• FetcherInterceptor: Provides the function of loading original image data from Uri, and loading original image data from the network, files, resources and other sources for Decoder to decode.
• DecoderInterceptor: Provides decoding function to decode the original image data into Bitmap

Interceptor provided by sketch-extensions-core module:

• PauseLoadWhenScrollingInterceptor: Provides the function of pausing the loading of pictures when the list slides, and resuming the loading of pictures when the slide stops.
• SaveCellularTrafficInterceptor: Provides the function to prohibit loading images from the network in non-Wi-Fi network environments

Custom Interceptor

First implement the Interceptor interface to define your Interceptor, as follows:

class MyInterceptor : Interceptor {

    // If the current Interceptor will modify the returned results and is only used for some requests, then please give a unique key to build the cache key, otherwise give null
    override val key: String? = null

    // Used for sorting, the larger the value, the further back in the list. The value range is 0 ~ 100. Usually zero. Only DecoderInterceptor can be 100
    override val sortWeight: Int = 0

    override suspend fun intercept(chain: Chain): Result<ImageData> {
        // Disable memory caching for all requests
        val newRequest = chain.request.newRequest {
            memoryCachePolicy(CachePolicy.DISABLED)
        }
        return chain.proceed(newRequest)
    }
}

Then register your Interceptor as follows:

// Register for all ImageRequests when customizing Sketch
Sketch.Builder(context).apply {
  components {
    addInterceptor(MyInterceptor())
  }
}.build()

// Register for a single ImageRequest when loading an image
ImageRequest(context, "https://example.com/image.jpg") {
    components {
        addInterceptor(MyInterceptor())
    }
}