ComposeRuntimeFlags

Summary

Public properties
Boolean

A feature flag than can be used to enable the link-list based slot table implementation instead of the gap buffer based slot table.
Cmn
Boolean

A feature flag that can be used to disable detecting nested movable content.
Cmn

Public properties

isLinkBufferComposerEnabled

Cmn 
var isLinkBufferComposerEnabled: Boolean

A feature flag than can be used to enable the link-list based slot table implementation instead of the gap buffer based slot table. The linked-list implementation is designed to improve performance primarily when deleting, moving, and reordering composable content by reducing the amount of internal array copy operations.

This flag is disabled by default.

This flag must be set to the desired value prior to calling setContent the first time and never change thereafter as the runtime does not support having multiple implementations of the slot table simultaneously.

For performance reasons, this flag is also configured via proguard rule for release builds so that production builds of apps can ship with only one implementation of the slot table. Leaving both implementations in a release build of an Android app will lead to measurable performance differences as it prevents R8 from devirtualizing calls in the Compose runtime. (Apps that do not currently optimize release builds with R8 are less likely to notice performance differences by having two parallel slot table implementations, though we continue to recommend enabling R8 as it makes a big difference to Compose's performance.)

To set this flag in release builds with R8, add this configuration to your module's proguard rules:

-assumevalues public class androidx.compose.runtime.ComposeRuntimeFlags {
    static boolean isLinkBufferComposerEnabled return true;
}

The Compose runtime ships with a default proguard configuration rule that matches this flag's default (disabled) value that ships with the library. Changing this field programmatically in an app optimized by R8 will only affect debug builds without the matching proguard rule. In R8 release builds, the proguard configuration always takes precedence and programmatic assignments to this flag become no-ops.

isMovingNestedMovableContentEnabled

Cmn
Added in 1.8.0
var isMovingNestedMovableContentEnabled: Boolean

A feature flag that can be used to disable detecting nested movable content.

The way movable is detected was changed to ensure that movable content that is no longer used, but was nested in other unused movable content, is made a candidate for moving to avoid state being lost. However, this is a change in behavior may have indirectly been relied on by an application. This flags allows detecting if any regressions are caused by this change in behavior and provides a temporary work-around.

This feature flag will eventually be depreciated and removed. All applications should be updated to ensure they are compatible with the new behavior.