packages/SystemUI/animation/src/com/android/systemui/animation/ViewRootSync.kt

package com.android.systemui.animation

import android.view.View
import android.window.SurfaceSyncer

/** A util class to synchronize 2 view roots. */
// TODO(b/200284684): Remove this class.
object ViewRootSync {
    private var surfaceSyncer: SurfaceSyncer? = null

    /**
     * Synchronize the next draw between the view roots of [view] and [otherView], then run [then].
     *
     * Note that in some cases, the synchronization might not be possible (e.g. WM consumed the
     * next transactions) or disabled (temporarily, on low ram devices). In this case, [then] will
     * be called without synchronizing.
     */
    fun synchronizeNextDraw(
        view: View,
        otherView: View,
        then: () -> Unit
    ) {
        if (!view.isAttachedToWindow || view.viewRootImpl == null ||
            !otherView.isAttachedToWindow || otherView.viewRootImpl == null ||
            view.viewRootImpl == otherView.viewRootImpl) {
            // No need to synchronize if either the touch surface or dialog view is not attached
            // to a window.
            then()
            return
        }

        surfaceSyncer = SurfaceSyncer().apply {
            val syncId = setupSync(Runnable { then() })
            addToSync(syncId, view)
            addToSync(syncId, otherView)
            markSyncReady(syncId)
        }
    }

    /**
     * A Java-friendly API for [synchronizeNextDraw].
     */
    @JvmStatic
    fun synchronizeNextDraw(view: View, otherView: View, then: Runnable) {
        synchronizeNextDraw(view, otherView, then::run)
    }
}