如何在CoordinatorLayout中滚动滚动顶部和底部工具栏（或任何其他视图）进入/退出屏幕？

Question

我的活动在CoordinatorLayout中包含2个AppBarLayouts，一个在屏幕顶部，另一个在底部。 我想让两个AppBarLayouts隐藏在RecyclerView的滚动上。

当只有最顶层的时候，通过将app:layout_scrollFlags="scroll|enterAlways"到工具栏，并将app:layout_behavior="@string/appbar_scrolling_view_behavior"到RecyclerView的容器中，可以很容易地将其隐藏在滚动上。

当只有底部的AppBarLayout隐藏在滚动上时，它通过自定义行为实现BottomAppBarLayoutBehavior extends AppBarLayout.Behavior 。

但是，当它们都在滚动时隐藏时，它们会成功隐藏但RecyclerView会在滚动时抖动。 顶部工具栏的区域在隐藏后留下空白空间。 下面是xml：

<android.support.design.widget.CoordinatorLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:android="http://schemas.android.com/apk/res/android">

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <android.support.v7.widget.Toolbar
            android:id="@+id/topToolbar"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            app:layout_scrollFlags="scroll|enterAlways" />

    </android.support.design.widget.AppBarLayout>

    <FrameLayout
        android:layout_width="fill_parent"
        android:orientation="vertical"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        android:id="@+id/RecyclerViewContainer"
        android:layout_height="fill_parent"/>

    <android.support.design.widget.AppBarLayout 
        android:layout_width="match_parent"
        android:layout_gravity="bottom"
        app:layout_behavior="myPackage.BottomAppBarLayoutBehavior">

        <LinearLayout
            android:layout_width="match_parent"
            android:orientation="horizontal"
            android:layout_height="match_parent">
            <!-- some Views -->
        </LinearLayout>

    </android.support.design.widget.AppBarLayout>

</android.support.design.widget.CoordinatorLayout>

以下是BottomAppBarLayoutBehavior的代码：

public class BottomAppBarLayoutBehavior extends AppBarLayout.Behavior {
    private static final Interpolator INTERPOLATOR = new FastOutSlowInInterpolator();
    private boolean mIsAnimatingOut = false;

    public BottomAppBarLayoutBehavior(Context context, AttributeSet attrs) {
        super();
    }

    @Override
    public boolean onStartNestedScroll(final CoordinatorLayout coordinatorLayout, final AppBarLayout child,
                                       final View directTargetChild, final View target, final int nestedScrollAxes) {
        return nestedScrollAxes == ViewCompat.SCROLL_AXIS_VERTICAL
                || super.onStartNestedScroll(coordinatorLayout, child, directTargetChild, target, nestedScrollAxes);
    }

    @Override
    public void onNestedScroll(final CoordinatorLayout coordinatorLayout, final AppBarLayout child,
                               final View target, final int dxConsumed, final int dyConsumed,
                               final int dxUnconsumed, final int dyUnconsumed) {
        super.onNestedScroll(coordinatorLayout, child, target, dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed);
        if (dyConsumed > 0 && !this.mIsAnimatingOut && child.getVisibility() == View.VISIBLE) {
            animateOut(child);
        } else if (dyConsumed < 0 && child.getVisibility() != View.VISIBLE) {
            animateIn(child);
        }
    }

    private void animateOut(final AppBarLayout appBarLayout) {
        if (Build.VERSION.SDK_INT >= 14) {
            ViewCompat.animate(appBarLayout).translationY(168F).alpha(0.0F).setInterpolator(INTERPOLATOR).withLayer()
                    .setListener(new ViewPropertyAnimatorListener() {
                        public void onAnimationStart(View view) {
                            BottomAppBarLayoutBehavior.this.mIsAnimatingOut = true;
                        }

                        public void onAnimationCancel(View view) {
                            BottomAppBarLayoutBehavior.this.mIsAnimatingOut = false;
                        }

                        public void onAnimationEnd(View view) {
                            BottomAppBarLayoutBehavior.this.mIsAnimatingOut = false;
                            view.setVisibility(View.GONE);
                        }
                    }).start();
        } else {
            Animation anim = AnimationUtils.loadAnimation(appBarLayout.getContext(), R.anim.fab_out);
            anim.setInterpolator(INTERPOLATOR);
            anim.setDuration(200L);
            anim.setAnimationListener(new Animation.AnimationListener() {
                public void onAnimationStart(Animation animation) {
                    BottomAppBarLayoutBehavior.this.mIsAnimatingOut = true;
                }

                public void onAnimationEnd(Animation animation) {
                    BottomAppBarLayoutBehavior.this.mIsAnimatingOut = false;
                    appBarLayout.setVisibility(View.GONE);
                }

                @Override
                public void onAnimationRepeat(final Animation animation) {
                }
            });
            appBarLayout.startAnimation(anim);
        }
    }

    private void animateIn(AppBarLayout appBarLayout) {
        appBarLayout.setVisibility(View.VISIBLE);
        if (Build.VERSION.SDK_INT >= 14) {
            ViewCompat.animate(appBarLayout).scaleX(1.0F).scaleY(1.0F).alpha(1.0F)
                    .setInterpolator(INTERPOLATOR).withLayer().setListener(null)
                    .start();
        } else {
            Animation anim = AnimationUtils.loadAnimation(appBarLayout.getContext(), R.anim.fab_in);
            anim.setDuration(200L);
            anim.setInterpolator(INTERPOLATOR);
            appBarLayout.startAnimation(anim);
        }
    }
}

Answer 1

我自己找到了解决方案。 底部LinearLayout的AppBarLayout包装器是多余的。 删除AppBarLayout包装并使Behavior类扩展CoordinatorLayout.Behavior<LinearLayout> 。 最后将行为添加到LinearLayout ，然后顶部Toolbar和底部LinearLayout进入和退出屏幕正确滚动。

正确的活动xml：

<android.support.design.widget.CoordinatorLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:android="http://schemas.android.com/apk/res/android">

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <android.support.v7.widget.Toolbar
            android:id="@+id/top_toolbar"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            app:layout_scrollFlags="scroll|enterAlways" />

    </android.support.design.widget.AppBarLayout>

    <FrameLayout
        android:layout_width="fill_parent"
        android:orientation="vertical"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        android:id="@+id/recycler_view_container"
        android:layout_height="fill_parent"/>

    <LinearLayout
        android:id="@+id/bottom_bar"
        android:layout_width="match_parent"
        android:orientation="horizontal"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom"
        app:layout_behavior="*THE_FULL_PACKAGE_NAME*.LinearLayoutBehavior ">
        <!-- child views -->
    </LinearLayout>

</android.support.design.widget.CoordinatorLayout>

正确的Behavior类：

public class LinearLayoutBehavior extends CoordinatorLayout.Behavior<LinearLayout> {
    private static final Interpolator INTERPOLATOR = new FastOutSlowInInterpolator();
    private boolean mIsAnimatingOut = false;

    public LinearLayoutBehavior(Context context, AttributeSet attrs) {
        super();
    }

    @Override
    public boolean onStartNestedScroll(final CoordinatorLayout coordinatorLayout, final LinearLayout child,
                                       final View directTargetChild, final View target, final int nestedScrollAxes) {
        return nestedScrollAxes == ViewCompat.SCROLL_AXIS_VERTICAL
                || super.onStartNestedScroll(coordinatorLayout, child, directTargetChild, target, nestedScrollAxes);
    }

    @Override
    public void onNestedScroll(final CoordinatorLayout coordinatorLayout, final LinearLayout child,
                               final View target, final int dxConsumed, final int dyConsumed,
                               final int dxUnconsumed, final int dyUnconsumed) {
        super.onNestedScroll(coordinatorLayout, child, target, dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed);
        if (dyConsumed > 0 && !this.mIsAnimatingOut && child.getVisibility() == View.VISIBLE) {
            // User scrolled down and the FAB is currently visible -> hide the FAB
            animateOut(child);
        } else if (dyConsumed < 0 && child.getVisibility() != View.VISIBLE) {
            // User scrolled up and the FAB is currently not visible -> show the FAB
            animateIn(child);
        }
    }

    private void animateOut(final LinearLayout linearLayout) {
        if (Build.VERSION.SDK_INT >= 14) {
            ViewCompat.animate(linearLayout).translationY(168F).alpha(0.0F).setInterpolator(INTERPOLATOR).withLayer()
                    .setListener(new ViewPropertyAnimatorListener() {
                        public void onAnimationStart(View view) {
                            LinearLayoutBehavior.this.mIsAnimatingOut = true;
                        }

                        public void onAnimationCancel(View view) {
                            LinearLayoutBehavior.this.mIsAnimatingOut = false;
                        }

                        public void onAnimationEnd(View view) {
                            LinearLayoutBehavior.this.mIsAnimatingOut = false;
                            view.setVisibility(View.GONE);
                        }
                    }).start();
        } else {
            Animation anim = AnimationUtils.loadAnimation(linearLayout.getContext(), R.anim.fab_out);
            anim.setInterpolator(INTERPOLATOR);
            anim.setDuration(200L);
            anim.setAnimationListener(new Animation.AnimationListener() {
                public void onAnimationStart(Animation animation) {
                    LinearLayoutBehavior.this.mIsAnimatingOut = true;
                }

                public void onAnimationEnd(Animation animation) {
                    LinearLayoutBehavior.this.mIsAnimatingOut = false;
                    linearLayout.setVisibility(View.GONE);
                }

                @Override
                public void onAnimationRepeat(final Animation animation) {
                }
            });
            linearLayout.startAnimation(anim);
        }
    }

    private void animateIn(LinearLayout linearLayout) {
        linearLayout.setVisibility(View.VISIBLE);
        if (Build.VERSION.SDK_INT >= 14) {
            ViewCompat.animate(linearLayout).translationY(0).scaleX(1.0F).scaleY(1.0F).alpha(1.0F)
                    .setInterpolator(INTERPOLATOR).withLayer().setListener(null)
                    .start();
        } else {
            Animation anim = AnimationUtils.loadAnimation(linearLayout.getContext(), R.anim.fab_in);
            anim.setDuration(200L);
            anim.setInterpolator(INTERPOLATOR);
            linearLayout.startAnimation(anim);
        }
    }
}