SplitController

@RequiresWindowSdkExtension(version = 2)
public final void clearSplitAttributesCalculator()

Clears the callback previously set by setSplitAttributesCalculator. The caller must make sure if WindowSdkExtensions.extensionVersion is greater than or equal to 2.

public static final @NonNull SplitController getInstance(@NonNull Context context)

Obtains an instance of SplitController.

public final @NonNull SplitController.SplitSupportStatus getSplitSupportStatus()

Indicates whether split functionality is supported on the device. Note that devices might not enable splits in all states or conditions. For example, a foldable device with multiple screens can choose to collapse splits when apps run on the device's small display, but enable splits when apps run on the device's large display. In cases like this, splitSupportStatus always returns SplitSupportStatus.SPLIT_AVAILABLE, and if the split is collapsed, activities are launched on top, following the non-activity embedding model.

Also the WindowProperties.PROPERTY_ACTIVITY_EMBEDDING_SPLITS_ENABLED must be enabled in AndroidManifest within in order to get the correct state or SplitSupportStatus.SPLIT_ERROR_PROPERTY_NOT_DECLARED will be returned in some cases.

@RequiresWindowSdkExtension(version = 5)
public final boolean pinTopActivityStack(int taskId, @NonNull SplitPinRule splitPinRule)

Pins the top-most ActivityStack to keep the stack of the Activities to be always positioned on top. The rest of the activities in the Task will be split with the pinned ActivityStack. The pinned ActivityStack would also have isolated activity navigation in which only the activities that are started from the pinned ActivityStack can be added on top of the ActivityStack.

The pinned ActivityStack is unpinned whenever the pinned ActivityStack is expanded. Use SplitPinRule.Builder.setSticky if the same ActivityStack should be pinned again whenever the ActivityStack is on top and split with another ActivityStack again.

The caller must make sure if WindowSdkExtensions.extensionVersion is greater than or equal to 5.

@RequiresWindowSdkExtension(version = 2)
public final void setSplitAttributesCalculator(
    @NonNull Function1<@NonNull SplitAttributesCalculatorParams, @NonNull SplitAttributes> calculator
)

Sets or replaces the previously registered SplitAttributes calculator.

Note that it's callers' responsibility to check if this API is supported by checking WindowSdkExtensions.extensionVersion before using the this API. It is suggested to always set meaningful SplitRule.defaultSplitAttributes in case this API is not supported on some devices.

Also, replacing the calculator will only update existing split pairs after a change in the window or device state, such as orientation changes or folding state changes.

The SplitAttributes calculator is a function to compute the current SplitAttributes for the given SplitRule with the current device and window state. Then The calculator will be invoked if either:

• An activity is started and matches a registered SplitRule.

• A parent configuration is updated and there's an existing split pair.

By default, SplitRule.defaultSplitAttributes are applied if the parent container's WindowMetrics satisfies the SplitRule's dimensions requirements, which are SplitRule.minWidthDp, SplitRule.minHeightDp and SplitRule.minSmallestWidthDp. The SplitRule.defaultSplitAttributes can be set by

• SplitRule Builder APIs, which are SplitPairRule.Builder.setDefaultSplitAttributes and SplitPlaceholderRule.Builder.setDefaultSplitAttributes.

• Specifying with splitRatio and splitLayoutDirection attributes in <SplitPairRule> or <SplitPlaceHolderRule> tags in XML files.

Developers may want to apply different SplitAttributes for different device or window states. For example, on foldable devices, developers may want to split the screen vertically if the device is in landscape, fill the screen if the device is in portrait and split the screen horizontally if the device is in tabletop posture. In this case, the SplitAttributes can be customized by the SplitAttributes calculator, which takes effects after calling this API. Developers can also clear the calculator by clearSplitAttributesCalculator. Then, developers could implement the SplitAttributes calculator as the sample linked below shows.

import androidx.window.embedding.EmbeddingAnimationBackground
import androidx.window.embedding.EmbeddingAnimationParams
import androidx.window.embedding.SplitAttributes
import androidx.window.embedding.SplitAttributes.SplitType.Companion.SPLIT_TYPE_EQUAL
import androidx.window.embedding.SplitAttributes.SplitType.Companion.SPLIT_TYPE_EXPAND
import androidx.window.embedding.SplitAttributes.SplitType.Companion.SPLIT_TYPE_HINGE
import androidx.window.embedding.SplitController
import androidx.window.layout.FoldingFeature

SplitController.getInstance(context).setSplitAttributesCalculator { params ->
    val tag = params.splitRuleTag
    val parentWindowMetrics = params.parentWindowMetrics
    val parentConfig = params.parentConfiguration
    val foldingFeatures =
        params.parentWindowLayoutInfo.displayFeatures.filterIsInstance<FoldingFeature>()
    val foldingState = if (foldingFeatures.size == 1) foldingFeatures[0] else null
    // Tag can be used to filter the SplitRule to apply the SplitAttributes
    if (TAG_SPLIT_RULE_MAIN != tag && params.areDefaultConstraintsSatisfied) {
        return@setSplitAttributesCalculator params.defaultSplitAttributes
    }

    // This sample will make the app show a layout to
    // - split the task bounds vertically if the device is in landscape
    // - fill the task bounds if the device is in portrait and its folding state does not
    //   split the screen
    // - split the task bounds horizontally in tabletop mode
    val bounds = parentWindowMetrics.bounds
    if (foldingState?.isSeparating == true) {
        // Split the parent container that followed by the hinge if the hinge separates the
        // parent window.
        return@setSplitAttributesCalculator SplitAttributes.Builder()
            .setSplitType(SPLIT_TYPE_HINGE)
            .setLayoutDirection(
                if (foldingState.orientation == FoldingFeature.Orientation.HORIZONTAL) {
                    SplitAttributes.LayoutDirection.TOP_TO_BOTTOM
                } else {
                    SplitAttributes.LayoutDirection.LOCALE
                }
            )
            // Optionally set the animation background and change transition animation to use
            // when switching between vertical and horizontal
            .setAnimationParams(
                EmbeddingAnimationParams.Builder()
                    .setAnimationBackground(
                        EmbeddingAnimationBackground.createColorBackground(Color.GRAY)
                    )
                    .setChangeAnimation(EmbeddingAnimationParams.AnimationSpec.JUMP_CUT)
                    .build()
            )
            .build()
    }
    return@setSplitAttributesCalculator if (
        parentConfig.screenWidthDp >= 600 && bounds.width() >= bounds.height()
    ) {
        // Split the parent container equally and vertically if the device is in landscape.
        SplitAttributes.Builder()
            .setSplitType(SPLIT_TYPE_EQUAL)
            .setLayoutDirection(SplitAttributes.LayoutDirection.LOCALE)
            // Optionally set the animation background and change transition animation to use
            // when switching between vertical and horizontal
            .setAnimationParams(
                EmbeddingAnimationParams.Builder()
                    .setAnimationBackground(
                        EmbeddingAnimationBackground.createColorBackground(Color.GRAY)
                    )
                    .setChangeAnimation(EmbeddingAnimationParams.AnimationSpec.JUMP_CUT)
                    .build()
            )
            .build()
    } else {
        // Expand containers if the device is in portrait or the width is less than 600 dp.
        SplitAttributes.Builder().setSplitType(SPLIT_TYPE_EXPAND).build()
    }
}

public final @NonNull Flow<@NonNull List<@NonNull SplitInfo>> splitInfoList(@NonNull Activity activity)

A Flow of SplitInfo list that contains the current split states that this activity is part of.

An activity can be in zero, one or more active splits. More than one active split is possible if an activity created multiple containers to side, stacked on top of each other. Or it can be in two different splits at the same time - in a secondary container for one (it was launched to the side) and in the primary for another (it launched another activity to the side). The reported splits in the list are ordered from bottom to top by their z-order, more recent splits appearing later. Guaranteed to be called at least once to report the most recent state.

@RequiresWindowSdkExtension(version = 5)
public final void unpinTopActivityStack(int taskId)

Unpins the pinned ActivityStack. The ActivityStack will still be the top-most ActivityStack right after unpinned, and the ActivityStack could be expanded or continue to be split with the next top ActivityStack if the current state matches any of the existing SplitPairRule. It is a no-op call if the task does not have a pinned ActivityStack.

The caller must make sure if WindowSdkExtensions.extensionVersion is greater than or equal to 5.

@RequiresWindowSdkExtension(version = 3)
public final void updateSplitAttributes(
    @NonNull SplitInfo splitInfo,
    @NonNull SplitAttributes splitAttributes
)

Updates the SplitAttributes of a split pair. This is an alternative to using a split attributes calculator callback set in setSplitAttributesCalculator, useful when apps only need to update the splits in a few cases proactively but rely on the default split attributes most of the time otherwise.

The provided split attributes will be used instead of the associated SplitRule.defaultSplitAttributes.

Note that the split attributes may be updated if split attributes calculator callback is registered and invoked. If setSplitAttributesCalculator is used, the callback will still be applied to each SplitInfo when there's either:

• A new Activity being launched.

• A window or device state updates (e,g. due to screen rotation or folding state update).

In most cases it is suggested to use ActivityEmbeddingController.invalidateTopVisibleActivityStacks if a calculator has been set through setSplitAttributesCalculator.