java - 如何通过在Android持久 Bottom Sheet 中向上滑动从隐藏状态进入折叠状态？

Question

将 Bottom Sheet 从折叠状态拖动到隐藏状态后，从屏幕底部向上滑动不会将 Bottom Sheet 打开到折叠状态，这在谷歌地图的 Bottom Sheet 中是可行的。像这样:

如果这不是库功能，如何实现这一点？

activity_main.xml 是:

<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout 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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <!-- include main content -->
    <include layout="@layout/content_main" />

    <!-- Adding bottom sheet after main content -->
    <include layout="@layout/bottom_sheet" />

</androidx.coordinatorlayout.widget.CoordinatorLayout>

bottom_sheet.xml 是:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/bottom_sheet"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="#ffffff"
    android:orientation="vertical"
    android:padding="12dp"
    app:behavior_hideable="true"
    app:behavior_peekHeight="100dp"
    app:layout_behavior="com.google.android.material.bottomsheet.BottomSheetBehavior">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="96dp"
        android:orientation="horizontal">

        <ImageView
            android:layout_width="84dp"
            android:layout_height="match_parent"
            android:padding="8dp"
            android:src="@drawable/ic_launcher_background" />

        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="5"
            android:orientation="vertical">

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Dandelion Chocolate"
                android:textColor="#000000"
                android:textSize="24sp"
                android:textStyle="bold" />

            <LinearLayout
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginTop="6dp"
                android:orientation="horizontal">

<!--                <android.support.v7.widget.AppCompatRatingBar
                    style="@style/Base.Widget.AppCompat.RatingBar.Small"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:numStars="5"
                    android:rating="4" />-->

                <TextView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:text="4.7"
                    android:textColor="@color/colorAccent" />

                <TextView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_marginLeft="8dp"
                    android:text="(51)"
                    android:textColor="@color/colorAccent" />

            </LinearLayout>

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginTop="6dp"
                android:text="12 min away"
                 />

        </LinearLayout>

    </LinearLayout>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="6dp"
        android:drawablePadding="16dp"
        android:text="740 Valencia St, San Fracisco, CA"
         />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="6dp"

        android:drawablePadding="16dp"
        android:text="(415) 349-0942"
         />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="6dp"
        android:drawablePadding="16dp"
        android:text="Wed, 10 AM - 9 PM"
/>
    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="12dp"
        android:background="@color/colorAccent"
        android:text="PROCEED PAYMENT"
        android:textColor="#fff" />

</LinearLayout>

content_main.xml 是:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#DEDEDE"

    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:showIn="@layout/activity_main">

</LinearLayout>

Activity 代码:

private BottomSheetBehavior sheetBehavior;
private LinearLayout bottom_sheet;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    bottom_sheet = findViewById(R.id.bottom_sheet);
    sheetBehavior = BottomSheetBehavior.from(bottom_sheet);



    sheetBehavior.setBottomSheetCallback(new BottomSheetBehavior.BottomSheetCallback() {
        @Override
        public void onStateChanged(@NonNull View view, int newState) {
            switch (newState) {
                case BottomSheetBehavior.STATE_HIDDEN:
                    break;
                case BottomSheetBehavior.STATE_EXPANDED: {
                    Log.d("Tag", "Close Sheet");
                }
                break;
                case BottomSheetBehavior.STATE_COLLAPSED: {
                    Log.d("Tag", "Expand Sheet");
                }
                break;
                case BottomSheetBehavior.STATE_DRAGGING:
                    break;
                case BottomSheetBehavior.STATE_SETTLING:
                    break;
            }
        }

        @Override
        public void onSlide(@NonNull View view, float v) {

        }
    });

Answer 1

使用 GestureDetector 检测向上滑动手势 ( documentation )。例如，您可以像这样实现 onFling 回调:

    @Override
    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
        boolean result = false;
        try {
            float diffY = e2.getY() - e1.getY();
            float diffX = e2.getX() - e1.getX();
            if (Math.abs(diffX) > Math.abs(diffY)) {
                // Horizontal swipe occurred
            }
            else if (Math.abs(diffY) > SWIPE_THRESHOLD && Math.abs(velocityY) > SWIPE_VELOCITY_THRESHOLD) {
                // Vertical swipe occurred
                if (diffY > 0) {
                    // Swipe to bottom
                } else {
                    onSwipeTop();
                }
                result = true;
            }
        } catch (Exception exception) {
            exception.printStackTrace();
        }
        return result;
    }

   private void onSwipeTop() {
       sheetBehavior.setState(BottomSheetBehavior.STATE_COLLAPSED)
   }