ComposeViewContext

@ExperimentalComposeViewContextApi
class ComposeViewContext
private constructor(
    composeViewContext: ComposeViewContext?,
    internal val view: View,
    internal val compositionContext: CompositionContext,
    internal val lifecycleOwner: LifecycleOwner,
    internal val savedStateRegistryOwner: SavedStateRegistryOwner,
    internal val viewModelStoreOwner: ViewModelStoreOwner?,
    matchesContext: Boolean = composeViewContext?.view?.context == view.context,
)

ComposeViewContext can be used to compose a ComposeView while it isn't attached to the view hierarchy. This is useful when prefetching items for a RecyclerView, for example. To use it, call AbstractComposeView.createComposition with the ComposeViewContext after the content has been set. If the ComposeView is never attached to the hierarchy, AbstractComposeView.disposeComposition must be called to release resources and stop composition. If the ComposeView is attached to the hierarchy, it will stop composition once it has been removed from the hierarchy and calling AbstractComposeView.disposeComposition is unnecessary. It will start again if the ComposeView.setContent is called again, the View is reattached to the hierarchy, or AbstractComposeView.createComposition is called again.

Secondary Constructors

constructor(
    view: View,
    compositionContext: CompositionContext =
        view.findViewTreeCompositionContext() ?: view.windowRecomposer,
    lifecycleOwner: LifecycleOwner =
        view.findViewTreeLifecycleOwner()
            ?: throw IllegalStateException(
                "Composed into a View which doesn't propagate ViewTreeLifecycleOwner!"
            ),
    savedStateRegistryOwner: SavedStateRegistryOwner =
        view.findViewTreeSavedStateRegistryOwner()
            ?: throw IllegalStateException(
                "Composed into a View which doesn't propagate ViewTreeSavedStateRegistryOwner!"
            ),
    viewModelStoreOwner: ViewModelStoreOwner? = view.findViewTreeViewModelStoreOwner(),
) : this(
    view.findViewTreeComposeViewContext(),
    view,
    compositionContext,
    lifecycleOwner,
    savedStateRegistryOwner,
    viewModelStoreOwner,
)

Constructs a ComposeViewContext to be used with AbstractComposeView.createComposition to compose content while the AbstractComposeView isn't attached.

Parameters

Functions

fun copy(
        view: View = this.view,
        compositionContext: CompositionContext = this.compositionContext,
        lifecycleOwner: LifecycleOwner = this.lifecycleOwner,
        savedStateRegistryOwner: SavedStateRegistryOwner = this.savedStateRegistryOwner,
        viewModelStoreOwner: ViewModelStoreOwner? = this.viewModelStoreOwner,
    ): ComposeViewContext

Construct a ComposeViewContext sharing parts with another ComposeViewContext.

Parameters

Code Examples

ComposeViewContextUnattachedSample

@OptIn(ExperimentalComposeViewContextApi::class)
fun ComposeViewContextUnattachedSample(attachedView: View) {
    val composeView = ComposeView(attachedView.context)
    composeView.setContent { Box(Modifier.fillMaxSize()) }
    // If a ComposeViewContext hasn't been attached to the hierarchy, create a new one for this view
    val composeViewContext =
        attachedView.findViewTreeComposeViewContext() ?: ComposeViewContext(attachedView)
    // start composing while composeView isn't attached
    composeView.createComposition(composeViewContext)
}