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Commit cf92b9b3 authored by omarmt's avatar omarmt
Browse files

Add ScrollController in PriorityNestedScrollConnection 

Now, `onStart` needs to provides a `ScrollController` to manage the
scrolling.

A PriorityNestedScrollConnection ensures only one ScrollController is
active at a time, guaranteeing methods are called in the correct
sequence.

The ScrollController provides control over the scroll gesture.
It allows you to:
- Scroll the content by a given pixel amount.
- Stop the scrolling with a given initial velocity.
- Cancel the current scroll operation.

Test: Refactor. Manually tested on the demo app and Flexiglass
Bug: 371984715
Flag: com.android.systemui.scene_container
Change-Id: I86724b73f4178995c39d167daea0a7de6370f7d4
parent 80d63f34

packages/SystemUI/compose/features/src/com/android/systemui/notifications/ui/composable/NotificationScrimNestedScrollConnection.kt

+35 −26
Original line number Diff line number Diff line
@@ -18,9 +18,11 @@ package com.android.systemui.notifications.ui.composable 


import androidx.compose.foundation.gestures.Orientation

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

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

import androidx.compose.ui.util.fastCoerceAtLeast

import androidx.compose.ui.util.fastCoerceAtMost

import com.android.compose.nestedscroll.PriorityNestedScrollConnection

import com.android.compose.nestedscroll.ScrollController



/**

 * A [NestedScrollConnection] that listens for all vertical scroll events and responds in the
@@ -58,34 +60,41 @@ fun NotificationScrimNestedScrollConnection( 
            offsetAvailable > 0 && (scrimOffset() < maxScrimOffset || isCurrentGestureOverscroll())

        },

        canStartPostFling = { false },

        canStopOnPreFling = { false },

        onStart = { offsetAvailable -> onStart(offsetAvailable) },

        onScroll = { offsetAvailable, _ ->

        onStart = { firstScroll ->

            onStart(firstScroll)

            object : ScrollController {

                override fun onScroll(deltaScroll: Float, source: NestedScrollSource): Float {

                    val currentHeight = scrimOffset()

                    val amountConsumed =

                if (offsetAvailable > 0) {

                        if (deltaScroll > 0) {

                            val amountLeft = maxScrimOffset - currentHeight

                    offsetAvailable.fastCoerceAtMost(amountLeft)

                            deltaScroll.fastCoerceAtMost(amountLeft)

                        } else {

                            val amountLeft = minScrimOffset() - currentHeight

                    offsetAvailable.fastCoerceAtLeast(amountLeft)

                            deltaScroll.fastCoerceAtLeast(amountLeft)

                        }

                    snapScrimOffset(currentHeight + amountConsumed)

            amountConsumed

        },

        onStop = { velocityAvailable ->

            onStop(velocityAvailable)

                    return amountConsumed

                }



                override suspend fun onStop(initialVelocity: Float): Float {

                    onStop(initialVelocity)

                    if (scrimOffset() < minScrimOffset()) {

                        animateScrimOffset(minScrimOffset())

                    }

                    // Don't consume the velocity on pre/post fling

            0f

        },

        onCancel = {

                    return 0f

                }



                override fun onCancel() {

                    onStop(0f)

                    if (scrimOffset() < minScrimOffset()) {

                        animateScrimOffset(minScrimOffset())

                    }

                }



                override fun canStopOnPreFling() = false

            }

        },

    )

}

packages/SystemUI/compose/features/src/com/android/systemui/notifications/ui/composable/NotificationStackNestedScrollConnection.kt

+24 −13
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ import androidx.compose.foundation.layout.offset 
import androidx.compose.runtime.Composable

import androidx.compose.runtime.remember

import androidx.compose.ui.Modifier

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

import androidx.compose.ui.input.nestedscroll.nestedScroll

import androidx.compose.ui.platform.LocalConfiguration

import androidx.compose.ui.platform.LocalDensity
@@ -30,6 +31,7 @@ import androidx.compose.ui.unit.IntOffset 
import androidx.compose.ui.unit.dp

import androidx.compose.ui.util.fastCoerceAtLeast

import com.android.compose.nestedscroll.PriorityNestedScrollConnection

import com.android.compose.nestedscroll.ScrollController

import kotlin.math.max

import kotlin.math.roundToInt

import kotlin.math.tanh
@@ -92,20 +94,29 @@ fun NotificationStackNestedScrollConnection( 
            offsetAvailable < 0f && offsetBeforeStart < 0f && !canScrollForward()

        },

        canStartPostFling = { velocityAvailable -> velocityAvailable < 0f && !canScrollForward() },

        canStopOnPreFling = { false },

        onStart = { offsetAvailable -> onStart(offsetAvailable) },

        onScroll = { offsetAvailable, _ ->

        onStart = { firstScroll ->

            onStart(firstScroll)

            object : ScrollController {

                override fun onScroll(deltaScroll: Float, source: NestedScrollSource): Float {

                    val minOffset = 0f

            val consumed = offsetAvailable.fastCoerceAtLeast(minOffset - stackOffset())

                    val consumed = deltaScroll.fastCoerceAtLeast(minOffset - stackOffset())

                    if (consumed != 0f) {

                        onScroll(consumed)

                    }

            consumed

        },

        onStop = { velocityAvailable ->

            onStop(velocityAvailable)

            velocityAvailable

                    return consumed

                }



                override suspend fun onStop(initialVelocity: Float): Float {

                    onStop(initialVelocity)

                    return initialVelocity

                }



                override fun onCancel() {

                    onStop(0f)

                }



                override fun canStopOnPreFling() = false

            }

        },

        onCancel = { onStop(0f) },

    )

}

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

+53 −44
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ package com.android.compose.animation.scene 


import androidx.compose.foundation.gestures.Orientation

import androidx.compose.ui.geometry.Offset

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

import androidx.compose.ui.unit.dp

import androidx.compose.ui.unit.round

import androidx.compose.ui.util.fastCoerceIn
@@ -27,6 +28,7 @@ import com.android.compose.animation.scene.content.Content 
import com.android.compose.animation.scene.content.state.TransitionState

import com.android.compose.animation.scene.content.state.TransitionState.HasOverscrollProperties.Companion.DistanceUnspecified

import com.android.compose.nestedscroll.PriorityNestedScrollConnection

import com.android.compose.nestedscroll.ScrollController

import kotlin.math.absoluteValue



internal typealias SuspendedValue<T> = suspend () -> T
@@ -66,6 +68,7 @@ internal class DraggableHandlerImpl( 
    internal val orientation: Orientation,

) : DraggableHandler {

    internal val nestedScrollKey = Any()



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

    private var dragController: DragControllerImpl? = null
@@ -345,6 +348,7 @@ private class DragControllerImpl( 
                    distance == DistanceUnspecified ||

                        swipeAnimation.contentTransition.isWithinProgressRange(desiredProgress) ->

                        desiredOffset



                    distance > 0f -> desiredOffset.fastCoerceIn(0f, distance)

                    else -> desiredOffset.fastCoerceIn(distance, 0f)

                }
@@ -545,6 +549,7 @@ internal class Swipes( 
            upOrLeftResult == null && downOrRightResult == null -> null

            (directionOffset < 0f && upOrLeftResult != null) || downOrRightResult == null ->

                upOrLeftResult



            else -> downOrRightResult

        }

    }
@@ -608,7 +613,6 @@ internal class NestedScrollHandlerImpl( 
            return overscrollSpec != null

        }



        var dragController: DragController? = null

        var isIntercepting = false



        return PriorityNestedScrollConnection(
@@ -669,10 +673,12 @@ internal class NestedScrollHandlerImpl( 
                            canChangeScene = isZeroOffset

                            isZeroOffset && hasNextScene(offsetAvailable)

                        }



                        NestedScrollBehavior.EdgeWithPreview -> {

                            canChangeScene = isZeroOffset

                            hasNextScene(offsetAvailable)

                        }



                        NestedScrollBehavior.EdgeAlways -> {

                            canChangeScene = true

                            hasNextScene(offsetAvailable)
@@ -710,53 +716,56 @@ internal class NestedScrollHandlerImpl( 


                canStart

            },

            // We need to maintain scroll priority even if the scene transition can no longer

            // consume the scroll gesture to allow us to return to the previous scene.

            canStopOnScroll = { _, _ -> false },

            canStopOnPreFling = { true },

            onStart = { offsetAvailable ->

            onStart = { firstScroll ->

                val pointersInfo = pointersInfo()

                scrollController(

                    dragController =

                        draggableHandler.onDragStarted(

                            pointersDown = pointersInfo.pointersDown,

                            startedPosition = pointersInfo.startedPosition,

                        overSlop = if (isIntercepting) 0f else offsetAvailable,

                            overSlop = if (isIntercepting) 0f else firstScroll,

                        ),

                    canChangeScene = canChangeScene,

                    pointersInfoOwner = pointersInfoOwner,

                )

            },

            onScroll = { offsetAvailable, _ ->

                val controller = dragController ?: error("Should be called after onStart")

        )

    }

}



private fun scrollController(

    dragController: DragController,

    canChangeScene: Boolean,

    pointersInfoOwner: PointersInfoOwner,

): ScrollController {

    return object : ScrollController {

        override fun onScroll(deltaScroll: Float, source: NestedScrollSource): Float {

            val pointersInfo = pointersInfoOwner.pointersInfo()

            if (pointersInfo.isMouseWheel) {

                // Do not support mouse wheel interactions

                    return@PriorityNestedScrollConnection 0f

                return 0f

            }



                // TODO(b/297842071) We should handle the overscroll or slow drag if the gesture is

                // initiated in a nested child.

                controller.onDrag(delta = offsetAvailable)

            },

            onStop = { velocityAvailable ->

                val controller = dragController ?: error("Should be called after onStart")

                try {

                    controller

                        .onStop(velocity = velocityAvailable, canChangeContent = canChangeScene)

            return dragController.onDrag(delta = deltaScroll)

        }



        override suspend fun onStop(initialVelocity: Float): Float {

            return dragController

                .onStop(velocity = initialVelocity, canChangeContent = canChangeScene)

                .invoke()

                } finally {

                    // onStop might still be running when a new gesture begins.

                    // To prevent conflicts, we should only remove the drag controller if it's the

                    // same one that was active initially.

                    if (dragController == controller) {

                        dragController = null

        }



        override fun onCancel() {

            dragController.onStop(velocity = 0f, canChangeContent = canChangeScene)

        }

            },

            onCancel = {

                val controller = dragController ?: error("Should be called after onStart")

                controller.onStop(velocity = 0f, canChangeContent = canChangeScene)

                dragController = null

            },

        )



        /**

         * We need to maintain scroll priority even if the scene transition can no longer consume

         * the scroll gesture to allow us to return to the previous scene.

         */

        override fun canCancelScroll(available: Float, consumed: Float) = false



        override fun canStopOnPreFling() = true

    }

}

packages/SystemUI/compose/scene/src/com/android/compose/nestedscroll/LargeTopAppBarNestedScrollConnection.kt

+34 −18
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ package com.android.compose.nestedscroll 


import androidx.compose.foundation.gestures.Orientation

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

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

import androidx.compose.ui.util.fastCoerceAtLeast

import androidx.compose.ui.util.fastCoerceAtMost
@@ -54,23 +55,38 @@ fun LargeTopAppBarNestedScrollConnection( 
            offsetAvailable > 0 && height() < maxHeight()

        },

        canStartPostFling = { false },

        canStopOnPreFling = { false },

        onStart = { /* do nothing */ },

        onScroll = { offsetAvailable, _ ->

        onStart = { LargeTopAppBarScrollController(height, maxHeight, minHeight, onHeightChanged) },

    )

}



private class LargeTopAppBarScrollController(

    val height: () -> Float,

    val maxHeight: () -> Float,

    val minHeight: () -> Float,

    val onHeightChanged: (Float) -> Unit,

) : ScrollController {

    override fun onScroll(deltaScroll: Float, source: NestedScrollSource): Float {

        val currentHeight = height()

        val amountConsumed =

                if (offsetAvailable > 0) {

            if (deltaScroll > 0) {

                val amountLeft = maxHeight() - currentHeight

                    offsetAvailable.fastCoerceAtMost(amountLeft)

                deltaScroll.fastCoerceAtMost(amountLeft)

            } else {

                val amountLeft = minHeight() - currentHeight

                    offsetAvailable.fastCoerceAtLeast(amountLeft)

                deltaScroll.fastCoerceAtLeast(amountLeft)

            }

        onHeightChanged(currentHeight + amountConsumed)

            amountConsumed

        },

        return amountConsumed

    }



    override suspend fun onStop(initialVelocity: Float): Float {

        // Don't consume the velocity on pre/post fling

        onStop = { 0f },

        onCancel = { /* do nothing */ },

    )

        return 0f

    }



    override fun onCancel() {

        // do nothing

    }



    override fun canStopOnPreFling() = false

}

packages/SystemUI/compose/scene/src/com/android/compose/nestedscroll/PriorityNestedScrollConnection.kt

+234 −130

File changed.

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