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Commit b29945a6 authored by omarmt's avatar omarmt
Browse files

NestedScrollToScene communicate desired behavior while scrolling 

This CL introduces a new node but no new behavior.
The NestedScrollConnection will be moved to SwipeToScene, in a following
CL.

Test: Just a refactor
Bug: 336710600
Flag: com.android.systemui.scene_container
Change-Id: Ib3485505bb639d9bc84d52f0796ee65253624aba
parent d441a8bc

packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/DraggableHandler.kt

+1 −0
Original line number Diff line number Diff line
@@ -64,6 +64,7 @@ internal class DraggableHandlerImpl( 
    internal val orientation: Orientation,

    internal val coroutineScope: CoroutineScope,

) : DraggableHandler {

    internal val nestedScrollKey = Any()

    /** The [DraggableHandler] can only have one active [DragController] at a time. */

    private var dragController: DragControllerImpl? = null

packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/NestedScrollToScene.kt

+64 −5
Original line number Diff line number Diff line
@@ -18,6 +18,9 @@ package com.android.compose.animation.scene 


import androidx.compose.foundation.gestures.Orientation

import androidx.compose.ui.Modifier

import androidx.compose.ui.geometry.Offset

import androidx.compose.ui.input.nestedscroll.NestedScrollConnection

import androidx.compose.ui.input.nestedscroll.NestedScrollSource

import androidx.compose.ui.input.nestedscroll.nestedScrollModifierNode

import androidx.compose.ui.node.DelegatableNode

import androidx.compose.ui.node.DelegatingNode
@@ -122,13 +125,55 @@ private data class NestedScrollToSceneElement( 
}



private class NestedScrollToSceneNode(

    layoutImpl: SceneTransitionLayoutImpl,

    orientation: Orientation,

    topOrLeftBehavior: NestedScrollBehavior,

    bottomOrRightBehavior: NestedScrollBehavior,

    isExternalOverscrollGesture: () -> Boolean,

    private var layoutImpl: SceneTransitionLayoutImpl,

    private var orientation: Orientation,

    private var topOrLeftBehavior: NestedScrollBehavior,

    private var bottomOrRightBehavior: NestedScrollBehavior,

    private var isExternalOverscrollGesture: () -> Boolean,

) : DelegatingNode() {

    lateinit var pointersInfoOwner: PointersInfoOwner

    private var scrollBehaviorOwner: ScrollBehaviorOwner? = null



    private fun requireScrollBehaviorOwner(): ScrollBehaviorOwner {

        var behaviorOwner = scrollBehaviorOwner

        if (behaviorOwner == null) {

            behaviorOwner = requireScrollBehaviorOwner(layoutImpl.draggableHandler(orientation))

            scrollBehaviorOwner = behaviorOwner

        }

        return behaviorOwner

    }



    val updateScrollBehaviorsConnection =

        object : NestedScrollConnection {

            /**

             * When using [NestedScrollConnection.onPostScroll], we can specify the desired behavior

             * before our parent components. This gives them the option to override our behavior if

             * they choose.

             *

             * The behavior can be communicated at every scroll gesture to ensure that the hierarchy

             * is respected, even if one of our descendant nodes changes behavior after we set it.

             */

            override fun onPostScroll(

                consumed: Offset,

                available: Offset,

                source: NestedScrollSource,

            ): Offset {

                // If we have some remaining scroll, that scroll can be used to initiate a

                // transition between scenes. We can assume that the behavior is only needed if

                // there is some remaining amount.

                if (available != Offset.Zero) {

                    requireScrollBehaviorOwner()

                        .updateScrollBehaviors(

                            topOrLeftBehavior = topOrLeftBehavior,

                            bottomOrRightBehavior = bottomOrRightBehavior,

                            isExternalOverscrollGesture = isExternalOverscrollGesture,

                        )

                }



                return Offset.Zero

            }

        }



    private var priorityNestedScrollConnection: PriorityNestedScrollConnection =

        scenePriorityNestedScrollConnection(

            layoutImpl = layoutImpl,
@@ -145,14 +190,22 @@ private class NestedScrollToSceneNode( 
            dispatcher = null,

        )



    private var updateScrollBehaviorsNestedScrollNode: DelegatableNode =

        nestedScrollModifierNode(

            connection = updateScrollBehaviorsConnection,

            dispatcher = null,

        )



    override fun onAttach() {

        pointersInfoOwner = requireAncestorPointersInfoOwner()

        delegate(nestedScrollNode)

        delegate(updateScrollBehaviorsNestedScrollNode)

    }



    override fun onDetach() {

        // Make sure we reset the scroll connection when this modifier is removed from composition

        priorityNestedScrollConnection.reset()

        scrollBehaviorOwner = null

    }



    fun update(
@@ -162,6 +215,12 @@ private class NestedScrollToSceneNode( 
        bottomOrRightBehavior: NestedScrollBehavior,

        isExternalOverscrollGesture: () -> Boolean,

    ) {

        this.layoutImpl = layoutImpl

        this.orientation = orientation

        this.topOrLeftBehavior = topOrLeftBehavior

        this.bottomOrRightBehavior = bottomOrRightBehavior

        this.isExternalOverscrollGesture = isExternalOverscrollGesture



        // Clean up the old nested scroll connection

        priorityNestedScrollConnection.reset()

        undelegate(nestedScrollNode)

packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/SwipeToScene.kt

+48 −5
Original line number Diff line number Diff line
@@ -22,9 +22,12 @@ import androidx.compose.ui.Modifier 
import androidx.compose.ui.geometry.Offset

import androidx.compose.ui.input.pointer.PointerEvent

import androidx.compose.ui.input.pointer.PointerEventPass

import androidx.compose.ui.node.DelegatableNode

import androidx.compose.ui.node.DelegatingNode

import androidx.compose.ui.node.ModifierNodeElement

import androidx.compose.ui.node.PointerInputModifierNode

import androidx.compose.ui.node.TraversableNode

import androidx.compose.ui.node.findNearestAncestor

import androidx.compose.ui.unit.IntSize



/**
@@ -53,7 +56,7 @@ private class SwipeToSceneNode( 
    draggableHandler: DraggableHandlerImpl,

    swipeDetector: SwipeDetector,

) : DelegatingNode(), PointerInputModifierNode {

    private val delegate =

    private val multiPointerDraggableNode =

        delegate(

            MultiPointerDraggableNode(

                orientation = draggableHandler.orientation,
@@ -74,21 +77,25 @@ private class SwipeToSceneNode( 
                // Make sure to update the delegate orientation. Note that this will automatically

                // reset the underlying pointer input handler, so previous gestures will be

                // cancelled.

                delegate.orientation = value.orientation

                multiPointerDraggableNode.orientation = value.orientation

            }

        }



    override fun onAttach() {

        delegate(ScrollBehaviorOwnerNode(draggableHandler.nestedScrollKey))

    }



    override fun onPointerEvent(

        pointerEvent: PointerEvent,

        pass: PointerEventPass,

        bounds: IntSize,

    ) = delegate.onPointerEvent(pointerEvent, pass, bounds)

    ) = multiPointerDraggableNode.onPointerEvent(pointerEvent, pass, bounds)



    override fun onCancelPointerInput() = delegate.onCancelPointerInput()

    override fun onCancelPointerInput() = multiPointerDraggableNode.onCancelPointerInput()



    private fun enabled(): Boolean {

        return draggableHandler.isDrivingTransition ||

            currentScene().shouldEnableSwipes(delegate.orientation)

            currentScene().shouldEnableSwipes(multiPointerDraggableNode.orientation)

    }



    private fun currentScene(): Scene {
@@ -116,3 +123,39 @@ private class SwipeToSceneNode( 
        return currentScene().shouldEnableSwipes(oppositeOrientation)

    }

}



/** Find the [ScrollBehaviorOwner] for the current orientation. */

internal fun DelegatableNode.requireScrollBehaviorOwner(

    draggableHandler: DraggableHandlerImpl

): ScrollBehaviorOwner {

    val ancestorNode =

        checkNotNull(findNearestAncestor(draggableHandler.nestedScrollKey)) {

            "This should never happen! Couldn't find a ScrollBehaviorOwner. " +

                "Are we inside an SceneTransitionLayout?"

        }

    return ancestorNode as ScrollBehaviorOwner

}



internal fun interface ScrollBehaviorOwner {

    fun updateScrollBehaviors(

        topOrLeftBehavior: NestedScrollBehavior,

        bottomOrRightBehavior: NestedScrollBehavior,

        isExternalOverscrollGesture: () -> Boolean,

    )

}



/**

 * We need a node that receives the desired behavior.

 *

 * TODO(b/353234530) move this logic into [SwipeToSceneNode]

 */

private class ScrollBehaviorOwnerNode(override val traverseKey: Any) :

    Modifier.Node(), TraversableNode, ScrollBehaviorOwner {

    override fun updateScrollBehaviors(

        topOrLeftBehavior: NestedScrollBehavior,

        bottomOrRightBehavior: NestedScrollBehavior,

        isExternalOverscrollGesture: () -> Boolean

    ) {

        // This method will be used to update the desired behavior in a following CL.

    }

}