应用于ScrollView的MotionScene中的OnSwipe过渡不起作用

Question

此刻，我试图理解MotionLayout（在“测试应用程序”中）以将其应用于更大的应用程序。

我正在尝试模拟可折叠的工具栏。

我用几个图像和ScrollView进行了布局：

布局

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.motion.widget.MotionLayout 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"
    android:id="@+id/motion_l"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layoutDescription="@xml/motion_test"
    tools:context=".MainActivity"
    tools:showPaths="true">

    <ImageView
        android:id="@+id/background_image"
        android:layout_width="0dp"
        android:layout_height="200dp"
        android:scaleType="centerCrop"
        android:src="@drawable/img_back"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent " />

    <TextView
        android:id="@+id/title"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginEnd="16dp"
        android:layout_marginBottom="16dp"
        android:text="Awsome title"
        android:textColor="#ffffff"
        app:layout_constraintBottom_toBottomOf="@id/background_image"
        app:layout_constraintEnd_toEndOf="parent "
        app:layout_constraintStart_toStartOf="parent" />

    <ImageView
        android:id="@+id/back_button"
        android:layout_width="32dp"
        android:layout_height="32dp"
        android:layout_marginStart="16dp"
        android:layout_marginTop="16dp"
        android:scaleType="centerCrop"
        android:src="@drawable/ic_launcher_background"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent " />

    <ScrollView
        android:id="@+id/scroll_view"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@id/background_image">

        <androidx.constraintlayout.widget.ConstraintLayout
            android:id="@+id/container"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:layout_constraintBottom_toTopOf="@+id/text1"
            app:layout_constraintTop_toTopOf="@+id/text1">

            <TextView
                android:id="@+id/text1"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_margin="8dp"
                android:text="@string/text_test"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toTopOf="parent" />

            <TextView
                android:id="@+id/text2"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_margin="8dp"
                android:text="@string/text_test"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toBottomOf="@id/text1" />
        </androidx.constraintlayout.widget.ConstraintLayout>

    </ScrollView>

    <ImageView
        android:id="@+id/logo"
        android:layout_width="64dp"
        android:layout_height="64dp"
        android:elevation="4dp"
        android:scaleType="centerCrop"
        android:src="@drawable/img_logo"
        app:layout_constraintBottom_toBottomOf="@id/background_image"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@id/background_image" />

</androidx.constraintlayout.motion.widget.MotionLayout>

然后我创建了MotionScene布局来处理过渡：

MotionScene xml

<?xml version="1.0" encoding="utf-8"?>
<MotionScene xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <Transition
        app:constraintSetEnd="@id/collapsed"
        app:constraintSetStart="@id/expanded">

        <OnSwipe
            app:dragDirection="dragUp"
            app:touchAnchorId="@id/scroll_view"
            app:touchAnchorSide="top" />

    </Transition>

    <ConstraintSet android:id="@+id/collapsed">

        <Constraint
            android:id="@id/background_image"
            android:layout_height="?attr/actionBarSize"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent">
            <CustomAttribute
                app:attributeName="imageAlpha"
                app:customIntegerValue="0" />
        </Constraint>

        <Constraint
            android:id="@id/logo"
            android:layout_width="64dp"
            android:layout_height="64dp"
            android:visibility="gone"
            app:layout_constraintBottom_toBottomOf="@id/background_image"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@id/background_image">
            <CustomAttribute
                app:attributeName="imageAlpha"
                app:customIntegerValue="0" />
        </Constraint>

        <Constraint
            android:id="@id/title"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:layout_constraintBottom_toBottomOf="@id/background_image"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="@id/background_image">
            <CustomAttribute
                app:attributeName="textColor"
                app:customColorValue="#000000" />
        </Constraint>
    </ConstraintSet>

    <ConstraintSet android:id="@+id/expanded">
        <Constraint
            android:id="@id/background_image"
            android:layout_height="200dp"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent">
            <CustomAttribute
                app:attributeName="imageAlpha"
                app:customIntegerValue="255" />
        </Constraint>

        <Constraint
            android:id="@id/logo"
            android:layout_width="64dp"
            android:layout_height="64dp"
            android:visibility="visible"
            app:layout_constraintBottom_toBottomOf="@id/background_image"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@id/background_image">
            <CustomAttribute
                app:attributeName="imageAlpha"
                app:customIntegerValue="255" />
        </Constraint>

        <Constraint
            android:id="@id/title"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_marginStart="16dp"
            android:layout_marginEnd="16dp"
            android:layout_marginBottom="16dp"
            android:scaleX="1.0"
            android:scaleY="1.0"
            app:layout_constraintBottom_toBottomOf="@id/background_image"
            app:layout_constraintEnd_toEndOf="parent "
            app:layout_constraintStart_toStartOf="parent">
            <CustomAttribute
                app:attributeName="textColor"
                app:customColorValue="#ffffff" />
        </Constraint>
    </ConstraintSet>

</MotionScene>

这是我遇到的问题。动画效果很好，但是只有在ImageView中执行手势时才可以。如果在ScrollView中执行手势，则忽略过渡。

如您在OnSwipe中所见，touchAnchorID已应用于scrollView。

也许无法应用于ScrollView？在那种情况下，可以采用哪种解决方案？

因为在“真实项目”中，视图是使用ScrollView完成的。