Jetpack Compose AndroidView in Compose UI

Composes an Android View obtained from factory. The factory block will be called exactly once to obtain the View being composed, and it is also guaranteed to be invoked on the UI thread. Therefore, in addition to creating the View, the factory block can also be used to perform one-off initializations and View constant properties' setting. The update block can run multiple times (on the UI thread as well) due to recomposition, and it is the right place to set the new properties. Note that the block will also run once right after the factory block completes.

AndroidView is commonly needed for using Views that are infeasible to be reimplemented in Compose and there is no corresponding Compose API. Common examples for the moment are WebView, SurfaceView, AdView, etc.

This overload of AndroidView does not automatically pool or reuse Views. If placed inside of a reusable container (including inside a LazyRowandroidx.compose.foundation.lazy.LazyRow or LazyColumnandroidx.compose.foundation.lazy.LazyColumn), the View instances will always be discarded and recreated if the composition hierarchy containing the AndroidView changes, even if its group structure did not change and the View could have conceivably been reused.

To opt-in for View reuse, call the overload of AndroidView that accepts an onReset callback, and provide a non-null implementation for this callback. Since it is expensive to discard and recreate View instances, reusing Views can lead to noticeable performance improvements — especially when building a scrolling list of AndroidViewsAndroidView. It is highly recommended to opt-in to View reuse when possible.

AndroidView will not clip its content to the layout bounds. Use View.setClipToOutline on the child View to clip the contents, if desired. Developers will likely want to do this with all subclasses of SurfaceView to keep its contents contained.

AndroidView has nested scroll interop capabilities if the containing view has nested scroll enabled. This means this Composable can dispatch scroll deltas if it is placed inside a container that participates in nested scroll. For more information on how to enable nested scroll interop:

Overloads

AndroidView

@Composable
@UiComposable
fun <T : View> AndroidView(
    factory: (Context) -> T,
    modifier: Modifier = Modifier,
    update: (T) -> Unit = NoOpUpdate
)

Parameters

Name	Description
`factory`	The block creating the View to be composed.
`modifier`	The modifier to be applied to the layout.
`update`	A callback to be invoked after the layout is inflated and upon recomposition to update the information and state of the view

AndroidView

@Composable
@UiComposable
fun <T : View> AndroidView(
    factory: (Context) -> T,
    modifier: Modifier = Modifier,
    onReset: ((T) -> Unit)? = null,
    onRelease: (T) -> Unit = NoOpUpdate,
    update: (T) -> Unit = NoOpUpdate
)

Parameters

Name	Description
`factory`	The block creating the View to be composed.
`modifier`	The modifier to be applied to the layout.
`onReset`	A callback invoked as a signal that the view is about to be attached to the composition hierarchy in a different context than its original creation. This callback is invoked before update and should prepare the view for general reuse. If `null` or not specified, the `AndroidView` instance will not support reuse, and the View instance will always be discarded whenever the AndroidView is moved or removed from the composition hierarchy.
`onRelease`	A callback invoked as a signal that this view instance has exited the composition hierarchy entirely and will not be reused again. Any additional resources used by the View should be freed at this time.
`update`	A callback to be invoked after the layout is inflated and upon recomposition to update the information and state of the view