我在Github中有一个项目：https://github.com/Ali-Rezaei/TMDb-Paging
我在其中使用MotionLayout：
<data>
<variable
name="movie"
type="com.sample.android.tmdb.vo.Movie" />
<variable
name="vm"
type="com.sample.android.tmdb.ui.detail.MovieDetailViewModel" />
</data>
<android.support.constraint.motion.MotionLayout
android:id="@+id/details_motion"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layoutDescription="@xml/scene_show_details">
<ImageView
android:id="@+id/details_backdrop"
android:layout_width="0dp"
android:layout_height="0dp"
android:scaleType="centerCrop"
app:imageUrl="@{movie.backdropPath}"
tools:ignore="ContentDescription" />
<View
android:id="@+id/details_backdrop_scrim"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="@id/details_backdrop"
app:layout_constraintEnd_toEndOf="@id/details_backdrop"
app:layout_constraintStart_toStartOf="@id/details_backdrop"
app:layout_constraintTop_toTopOf="@id/details_backdrop" />
<android.support.v7.widget.AppCompatImageView
android:id="@+id/details_poster"
android:layout_width="0dp"
android:layout_height="0dp"
android:background="@drawable/placeholder"
android:scaleType="centerCrop"
android:transformPivotX="0px"
android:transformPivotY="0px"
android:transitionName="@string/view_name_header_image"
app:imageUrl="@{movie.posterPath}" />
<!-- Needed to fill a rounding error gap in MotionLayout. See https://issuetracker.google.com/112728689 -->
<View
android:id="@+id/details_gap_filler"
android:layout_width="match_parent"
android:layout_height="2px"
android:background="@color/window_background"
app:layout_constraintBottom_toTopOf="@id/details_rv"
tools:ignore="PxUsage" />
<com.sample.android.tmdb.widget.TopLeftCutoutBackgroundView
android:id="@+id/details_appbar_background"
android:layout_width="0dp"
android:layout_height="0dp"
app:backgroundColor="@color/window_background"
app:topLeftCutSize="@dimen/details_corner_cutout" />
<android.support.v7.widget.AppCompatTextView
android:id="@+id/details_title"
android:layout_width="0dp"
android:layout_height="0dp"
android:ellipsize="end"
android:text="@{movie.title}"
android:textAppearance="@style/TextAppearance.AppCompat.Title"
android:transitionName="@string/view_name_header_title" />
<android.support.v7.widget.Toolbar
android:id="@+id/details_toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:minHeight="?attr/actionBarSize"
app:theme="@style/Toolbar" />
<android.support.v4.widget.NestedScrollView
android:id="@+id/details_rv"
android:layout_width="0dp"
android:layout_height="0dp"
android:background="@color/window_background"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@id/details_appbar_background">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="@dimen/padding_normal"
android:layout_marginTop="@dimen/padding_normal"
android:layout_marginRight="@dimen/padding_normal"
android:layout_marginBottom="@dimen/padding_micro"
android:fontFamily="sans-serif-light"
android:text="@{@string/release_date(movie.releaseDate)}"
android:textAppearance="@style/TextAppearance.AppCompat.Small" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="@dimen/padding_normal"
android:layout_marginRight="@dimen/padding_normal"
android:fontFamily="sans-serif-light"
android:text="@{@string/rating(movie.voteAverage)}"
android:textAppearance="@style/TextAppearance.AppCompat.Small" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="@dimen/padding_normal"
android:layout_marginTop="@dimen/padding_large"
android:layout_marginRight="@dimen/padding_normal"
android:text="@string/summary"
android:textAppearance="@style/TextAppearance.AppCompat.Title" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="@dimen/padding_normal"
android:fontFamily="sans-serif-light"
android:text="@{movie.overview}"
android:textAppearance="@style/TextAppearance.AppCompat.Body1" />
<include
layout="@layout/trailers"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="@dimen/padding_normal"
android:layout_marginTop="@dimen/padding_normal"
android:layout_marginBottom="@dimen/padding_normal"
app:vm="@{vm}"
tools:ignore="RtlHardcoded" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="@dimen/padding_normal"
android:layout_marginRight="@dimen/padding_normal"
android:layout_marginBottom="12dp"
android:text="@string/actors"
android:textAppearance="@style/TextAppearance.AppCompat.Title"
app:visibleGone="@{vm.isActorsVisible}" />
<android.support.v7.widget.RecyclerView
android:id="@+id/actors"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:items="@{vm.casts}"
app:layout_behavior="@string/appbar_scrolling_view_behavior" />
</LinearLayout>
</android.support.v4.widget.NestedScrollView>
<!-- This needs to be updated to use WindowInsets. See https://issuetracker.google.com/issues/112605433 -->
<View
android:id="@+id/details_status_bar_anchor"
android:layout_width="match_parent"
android:layout_height="24dp"
android:background="@color/status_bar_scrim_translucent_dark" />
</android.support.constraint.motion.MotionLayout>
有时RecyclerView（带有id演员）会跳转到NestedScrollView中的其他视图。
您可以在没有回收器的情况下查看正确的行为： https://github.com/Ali-Rezaei/TMDb-Paging/tree/master
当嵌套滚动视图中的其他视图高度较短时，就会发生这种情况。你知道为什么会这样吗？
我试过了：
<android.support.v4.widget.NestedScrollView
android:id="@+id/details_rv"
android:layout_width="0dp"
android:layout_height="0dp"
android:background="@color/window_background"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent">
...
</android.support.v4.widget.NestedScrollView>
<android.support.v7.widget.RecyclerView
android:id="@+id/details_cast"
android:layout_width="0dp"
android:layout_height="0dp"
app:items="@{vm.cast}"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/details_rv" />
但它在RecyclerView中没有显示演员表。
这是scene_show_details：
<MotionScene xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">
<Transition
app:constraintSetEnd="@id/end"
app:constraintSetStart="@id/start"
app:duration="200">
<OnSwipe
app:dragDirection="dragUp"
app:moveWhenScrollAtTop="true"
app:touchAnchorId="@id/details_rv"
app:touchAnchorSide="top" />
<KeyFrameSet>
<KeyPosition
app:framePosition="20"
app:keyPositionType="deltaRelative"
app:percentY="0.51"
app:target="@id/details_poster" />
<!-- This looks weird. We need a quick change from elevated to not-so-elevated at 20% so we set 2 key
attributes, one at 20% and other at 25%. -->
<KeyAttribute
android:elevation="@dimen/z_app_bar"
android:rotation="45"
android:rotationY="15"
app:framePosition="20"
app:target="@id/details_poster" />
<KeyAttribute
android:elevation="@dimen/details_poster_not_elevation"
app:framePosition="25"
app:target="@id/details_poster" />
<!-- Only elevate the appbar background over the last 25% -->
<KeyAttribute
android:elevation="0dp"
app:framePosition="75"
app:target="@id/details_appbar_background" />
</KeyFrameSet>
</Transition>
<ConstraintSet android:id="@+id/start">
<Constraint
android:id="@id/details_backdrop"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="@id/details_appbar_background"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Constraint
android:id="@id/details_backdrop_scrim"
app:layout_constraintBottom_toBottomOf="@id/details_backdrop"
app:layout_constraintEnd_toEndOf="@id/details_backdrop"
app:layout_constraintStart_toStartOf="@id/details_backdrop"
app:layout_constraintTop_toTopOf="@id/details_backdrop">
<CustomAttribute
app:attributeName="background"
app:customColorDrawableValue="@android:color/transparent" />
</Constraint>
<Constraint
android:id="@id/details_toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:elevation="0dp"
app:layout_constraintTop_toBottomOf="@id/details_status_bar_anchor">
<CustomAttribute
app:attributeName="iconTint"
app:customColorValue="?android:attr/textColorPrimaryInverse" />
</Constraint>
<Constraint
android:id="@id/details_appbar_background"
android:layout_width="0dp"
android:layout_height="88dp"
app:layout_constraintBottom_toBottomOf="@id/details_poster"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
<Constraint
android:id="@id/details_title"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="24dp"
app:layout_constraintBottom_toTopOf="@id/details_appbar_background"
app:layout_constraintEnd_toEndOf="@id/details_appbar_background"
app:layout_constraintStart_toEndOf="@id/details_poster"
app:layout_constraintTop_toBottomOf="@id/details_appbar_background" />
<Constraint
android:id="@id/details_poster"
android:layout_width="80dp"
android:layout_height="0dp"
android:layout_marginStart="@dimen/padding_normal"
android:layout_marginTop="200dp"
android:elevation="@dimen/z_app_bar"
app:layout_constraintDimensionRatio="h,1:1.5"
app:layout_constraintStart_toStartOf="@id/details_rv"
app:layout_constraintTop_toTopOf="parent" />
</ConstraintSet>
<ConstraintSet android:id="@+id/end">
<Constraint
android:id="@id/details_backdrop"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="@id/details_appbar_background"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Constraint
android:id="@id/details_backdrop_scrim"
app:layout_constraintBottom_toBottomOf="@id/details_backdrop"
app:layout_constraintEnd_toEndOf="@id/details_backdrop"
app:layout_constraintStart_toStartOf="@id/details_backdrop"
app:layout_constraintTop_toTopOf="@id/details_backdrop">
<CustomAttribute
app:attributeName="background"
app:customColorDrawableValue="@color/status_bar_scrim_translucent_dark" />
</Constraint>
<Constraint
android:id="@id/details_toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:elevation="@dimen/z_app_bar"
app:layout_constraintTop_toBottomOf="@id/details_status_bar_anchor">
<CustomAttribute
app:attributeName="iconTint"
app:customColorValue="?android:attr/textColorPrimary" />
</Constraint>
<Constraint
android:id="@id/details_appbar_background"
android:layout_width="0dp"
android:layout_height="?android:attr/actionBarSize"
android:elevation="@dimen/z_app_bar"
app:layout_constraintEnd_toEndOf="@id/details_rv"
app:layout_constraintStart_toStartOf="@id/details_rv"
app:layout_constraintTop_toBottomOf="@id/details_status_bar_anchor" />
<Constraint
android:id="@id/details_title"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginEnd="48dp"
android:layout_marginStart="64dp"
android:elevation="@dimen/z_app_bar"
app:layout_constraintBottom_toBottomOf="@id/details_appbar_background"
app:layout_constraintEnd_toEndOf="@id/details_appbar_background"
app:layout_constraintStart_toStartOf="@id/details_appbar_background"
app:layout_constraintTop_toTopOf="@id/details_appbar_background" />
<Constraint
android:id="@id/details_poster"
android:layout_width="72dp"
android:layout_height="0dp"
android:elevation="@dimen/details_poster_not_elevation"
app:layout_constraintDimensionRatio="h,1:1.5"
app:layout_constraintStart_toStartOf="@id/details_title"
app:layout_constraintTop_toBottomOf="@id/details_status_bar_anchor" />
</ConstraintSet>
</MotionScene>
问题跟踪可以在以下位置找到： https://issuetracker.google.com/issues/121439694