android - Android：如何在 CoordinatorLayout 和 LayoutBehaviour 中翻译和展开视图

Question

我目前正在我的应用程序中执行以下操作：用户在视图中有两个元素，即图像和很长的文本。当用户滚动文本时，它会根据他的移动上下移动。当它上升时，文本在内部滚动之前上升到图像高度的一半，然后如果它返回，它会向下滚动执行相反的操作。目前我可以重现所有这些，但我唯一的问题是我只能获得翻译。我想为视图的整个可用部分扩展文本视图，而不仅仅是翻译它。

以下是引用当前结果的图像：

Start Position向上滚动之前是：

End position向上滚动后是：

我想在向上滚动后获得 NestedScrollView 占用所有空间而不仅仅是翻译，如下所示：

这是我的代码。我使用以编程方式添加的布局行为来执行向上或向下滚动的操作：

    import android.content.Context
    import android.util.AttributeSet
    import android.view.View
    import androidx.coordinatorlayout.widget.CoordinatorLayout
    import androidx.core.view.ViewCompat
    import androidx.core.widget.NestedScrollView
    import org.slf4j.Logger
    import org.slf4j.LoggerFactory
    
    class CollapseBehavior @JvmOverloads constructor(
        context: Context? = null,
        attrs: AttributeSet? = null,
        private val brandHeaderImage: View
    ) :
        CoordinatorLayout.Behavior<View>(context, attrs) {
    
        private val logger: Logger = LoggerFactory.getLogger(CollapseBehavior::class.java)
        private var currentOffset = 0
        private var maxOffset = 0
        private lateinit var topView: View
    
        // have to accept nested scrolling event to participate in it
        override fun onStartNestedScroll(
            coordinatorLayout: CoordinatorLayout, child: View, directTargetChild: View,
            target: View, axes: Int, type: Int
        ): Boolean {
            topView = brandHeaderImage
            maxOffset = topView.height / 2     // tweak maxOffset if needed
            return axes == ViewCompat.SCROLL_AXIS_VERTICAL && target is NestedScrollView
        }
    
        // this allows us to steal the scrolling distance
        // use it to offset NestedScrollView before it gets to scroll
        override fun onNestedPreScroll(
            coordinatorLayout: CoordinatorLayout, child: View, target: View,
            dx: Int, dy: Int, consumed: IntArray, type: Int
        ) {
            logger.debug("Consumed dy: $dy")
            if (dy > 0) performOffset(target, dy, consumed)
        }
    
        // this allows us to consume remaining scrolling distance
        // use it to offset NestedScrollView after it gets scrolled back to start
        override fun onNestedScroll(
            coordinatorLayout: CoordinatorLayout, child: View, target: View,
            dxConsumed: Int, dyConsumed: Int,
            dxUnconsumed: Int, dyUnconsumed: Int,
            type: Int, consumed: IntArray
        ) {
            logger.debug("Consumed dyUnconsumed: $dyUnconsumed")
            if (dyUnconsumed < 0) performOffset(target, dyUnconsumed, consumed)
        }
    
        private fun performOffset(target: View, dy: Int, consumed: IntArray) {
            val targetOffset = currentOffset + dy
            val consumedScroll = targetOffset.coerceIn(0, maxOffset) - currentOffset
            currentOffset += consumedScroll
            target.translationY = -currentOffset.toFloat()
            consumed[1] = consumedScroll
        }
    }

以下是如何以编程方式设置 layout_behaviour：

           val collapseBehavior =
            CollapseBehavior(context = activity, view = view)
            BrandHeaderUtil.enableLayoutBehaviour(frameImageView, collapseBehavior)

这里是我的 xml：

    <?xml version="1.0" encoding="utf-8"?>
    <layout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools">
    
        <androidx.constraintlayout.widget.ConstraintLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">
    
            <com.google.android.material.appbar.MaterialToolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="?attr/actionBarSize"
                android:background="@color/hawkes_blue"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toTopOf="parent"
                app:layout_constraintVertical_chainStyle="spread_inside"
                app:title="app test">
    
                <Button
                    android:id="@+id/reset"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_gravity="end|center_vertical"
                    android:layout_margin="10dp"
                    android:backgroundTint="@color/white"
                    android:padding="5dp"
                    android:text="Reset"
                    android:textColor="@color/red"
                    android:textSize="12sp" />
    
            </com.google.android.material.appbar.MaterialToolbar>
    
            <androidx.coordinatorlayout.widget.CoordinatorLayout
                android:id="@+id/behaviour"
                android:layout_width="match_parent"
                android:layout_height="0dp"
                app:layout_constraintBottom_toBottomOf="parent"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toBottomOf="@+id/toolbar">
    
                <androidx.constraintlayout.widget.ConstraintLayout
                    android:layout_width="match_parent"
                    android:layout_height="match_parent">
    
                    <FrameLayout
                        android:id="@+id/imageContainer"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:background="@drawable/placeholder_image"
                        android:fitsSystemWindows="true"
                        app:layout_constraintEnd_toEndOf="parent"
                        app:layout_constraintStart_toStartOf="parent"
                        app:layout_constraintTop_toTopOf="parent" />
    
                    <androidx.core.widget.NestedScrollView
                        android:id="@+id/scroll"
                        android:layout_width="match_parent"
                        android:layout_height="0dp"
                        android:layout_gravity="bottom"
                        android:fitsSystemWindows="true"
                        app:layout_anchor="@id/imageContainer"
                        app:layout_anchorGravity="bottom"
                        app:layout_constraintBottom_toBottomOf="parent"
                        app:layout_constraintEnd_toEndOf="parent"
                        app:layout_constraintStart_toStartOf="parent"
                        app:layout_constraintTop_toBottomOf="@+id/advContainer">
    
                        <androidx.recyclerview.widget.RecyclerView
                            android:id="@+id/recyclerView"
                            android:layout_width="match_parent"
                            android:layout_height="wrap_content"
                            android:background="@color/white"
                            app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
                            app:layout_constraintEnd_toEndOf="parent"
                            app:layout_constraintStart_toStartOf="parent"
                            app:layout_constraintTop_toTopOf="parent"
                            tools:listitem="@layout/button_list" />
    
                    </androidx.core.widget.NestedScrollView>
                </androidx.constraintlayout.widget.ConstraintLayout>
            </androidx.coordinatorlayout.widget.CoordinatorLayout>
        </androidx.constraintlayout.widget.ConstraintLayout>
    </layout>

标签： androidkotlin