Android 滚动片段时隐藏BottomNavigationView（WebView）

或

class BottomNavigationBehavior扩展了CoordinatorLayout.Behavior

你不工作了

-主要活动布局

class BottomNavigationBehavior extends CoordinatorLayout.Behavior<BottomNavigationView>

-框架布局中的碎片布局（容器）

在我看来，webview嵌入在固定大小的框架布局中，滚动应用于webview本身。

---

我只是在学习安卓，所以我不确定。我需要一些帮助。

经过调查，我发现WebView没有实现NestedScroll处理程序。所以，即使是在关注其他关于如何应对这一事件的帖子，它们也不起作用

这里有一个github回购协议，您可以找到一个简单的解决方案

您只需要用NestedWebView覆盖WebView

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">


    <WebView
        android:id="@+id/webview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</RelativeLayout>

然后，在XML上使用它

/*
 * Copyright (C) 2015 takahirom
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.github.takahirom.webview_in_coodinator_layout;

import android.content.Context;
import android.support.v4.view.MotionEventCompat;
import android.support.v4.view.NestedScrollingChild;
import android.support.v4.view.NestedScrollingChildHelper;
import android.support.v4.view.ViewCompat;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.webkit.WebView;

public class NestedWebView extends WebView implements NestedScrollingChild {
    private int mLastY;
    private final int[] mScrollOffset = new int[2];
    private final int[] mScrollConsumed = new int[2];
    private int mNestedOffsetY;
    private NestedScrollingChildHelper mChildHelper;

    public NestedWebView(Context context) {
        this(context, null);
    }

    public NestedWebView(Context context, AttributeSet attrs) {
        this(context, attrs, android.R.attr.webViewStyle);
    }

    public NestedWebView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        mChildHelper = new NestedScrollingChildHelper(this);
        setNestedScrollingEnabled(true);
    }

    @Override
    public boolean onTouchEvent(MotionEvent ev) {
        boolean returnValue = false;

        MotionEvent event = MotionEvent.obtain(ev);
        final int action = MotionEventCompat.getActionMasked(event);
        if (action == MotionEvent.ACTION_DOWN) {
            mNestedOffsetY = 0;
        }
        int eventY = (int) event.getY();
        event.offsetLocation(0, mNestedOffsetY);
        switch (action) {
            case MotionEvent.ACTION_MOVE:
                int deltaY = mLastY - eventY;
                // NestedPreScroll
                if (dispatchNestedPreScroll(0, deltaY, mScrollConsumed, mScrollOffset)) {
                    deltaY -= mScrollConsumed[1];
                    mLastY = eventY - mScrollOffset[1];
                    event.offsetLocation(0, -mScrollOffset[1]);
                    mNestedOffsetY += mScrollOffset[1];
                }
                returnValue = super.onTouchEvent(event);

                // NestedScroll
                if (dispatchNestedScroll(0, mScrollOffset[1], 0, deltaY, mScrollOffset)) {
                    event.offsetLocation(0, mScrollOffset[1]);
                    mNestedOffsetY += mScrollOffset[1];
                    mLastY -= mScrollOffset[1];
                }
                break;
            case MotionEvent.ACTION_DOWN:
                returnValue = super.onTouchEvent(event);
                mLastY = eventY;
                // start NestedScroll
                startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL);
                break;
            case MotionEvent.ACTION_UP:
            case MotionEvent.ACTION_CANCEL:
                returnValue = super.onTouchEvent(event);
                // end NestedScroll
                stopNestedScroll();
                break;
        }
        return returnValue;
    }

    // Nested Scroll implements
    @Override
    public void setNestedScrollingEnabled(boolean enabled) {
        mChildHelper.setNestedScrollingEnabled(enabled);
    }

    @Override
    public boolean isNestedScrollingEnabled() {
        return mChildHelper.isNestedScrollingEnabled();
    }

    @Override
    public boolean startNestedScroll(int axes) {
        return mChildHelper.startNestedScroll(axes);
    }

    @Override
    public void stopNestedScroll() {
        mChildHelper.stopNestedScroll();
    }

    @Override
    public boolean hasNestedScrollingParent() {
        return mChildHelper.hasNestedScrollingParent();
    }

    @Override
    public boolean dispatchNestedScroll(int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed,
                                        int[] offsetInWindow) {
        return mChildHelper.dispatchNestedScroll(dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed, offsetInWindow);
    }

    @Override
    public boolean dispatchNestedPreScroll(int dx, int dy, int[] consumed, int[] offsetInWindow) {
        return mChildHelper.dispatchNestedPreScroll(dx, dy, consumed, offsetInWindow);
    }

    @Override
    public boolean dispatchNestedFling(float velocityX, float velocityY, boolean consumed) {
        return mChildHelper.dispatchNestedFling(velocityX, velocityY, consumed);
    }

    @Override
    public boolean dispatchNestedPreFling(float velocityX, float velocityY) {
        return mChildHelper.dispatchNestedPreFling(velocityX, velocityY);
    }

}

最后，您需要创建一个BottomBehaviorLayout并将其分配给BottomNavigationView，我在前面提到的repo中使用了这个简单的版本。这是下一个要点：

public final类BottomNavigationBehavior扩展了VerticalScrollingBehavior{
专用静态最终插值器插值器=新的LinearOutSlowInInterpolator（）；
私有最终底部导航WithNackBar mWithSnackBarImpl=Build.VERSION.SDK\u INT>=Build.VERSION\u CODES.LOLLIPOP？新的棒棒糖便当WithNackBarImpl（）：新的预列当便当WithNackBarImpl（）；
私有布尔表；
私有int-mTabLayoutId；
私有布尔隐藏=假；
private ViewPropertyAnimatorCompat mOffsetValueAnimator；
私有视图组mTabLayout；
私人视图持有人；
private int mSnackbarHeight=-1；
私有布尔scrollingEnabled=true；
私有布尔hideAlongSnackbar=false；
int[]attrsArray=新int[]{
android.R.attr.id}；
公共导航行为（）{
超级（）；
}
公共底部导航行为（上下文、属性集属性）{
超级（上下文，attrs）；
TypedArray a=上下文。获取样式属性（属性，
吸引子；
mTabLayoutId=a.getResourceId（0，视图。无\u ID）；
a、 回收（）；
}
公共静态BottomNavigationBehavior from（@NonNull V view）{
ViewGroup.LayoutParams params=view.getLayoutParams（）；
if（！（参数CoordinatorLayout.LayoutParams的实例））{
抛出新的IllegalArgumentException（“视图不是CoordinatorLayout的子视图”）；
}
CoordinatorLayout.Behavior行为=（（CoordinatorLayout.LayoutParams）参数）
.getBehavior（）；
if（！（底部导航行为的行为实例））{
抛出新的IllegalArgumentException(
“该视图未与BottomNavigationBehavior关联”）；
}
返回（BottomNavigationBehavior）行为；
}
@凌驾
公共布尔布局依赖项（协调布局父项、V子项、视图依赖项）{
mWithSnackBarImpl.updateSnackbar（父项、依赖项、子项）；
返回Snackbar.Snackbar布局的依赖实例；
}
@凌驾
移除了OnDependentViewPublic void（协调布局父项、V子项、视图依赖项）{
UpdateScrollingForNackBar（依赖项，子项，true）；
super.onDependentViewRemoved（父、子、依赖项）；
}
私有void updateScrollingForNackBar（视图依赖项，V子级，启用布尔值）{
if（！isTablet&&dependency instanceof Snackbar.Snackbar布局）{
scrollingEnabled=已启用；
如果（！hideAlongSnackbar&&ViewCompat.getTranslation（child）！=0）{
ViewCompat.setTranslationY（子对象，0）；
隐藏=错误；
hideAlongSnackbar=真；
}else if（hideAlongSnackbar）{
隐藏=真实；
animateOffset（child，-child.getHeight（））；
}
}
}
@凌驾
公共布尔onDependentViewChanged（协调布局父项、V子项、视图依赖项）{
UpdateScrollingForNackBar（依赖项、子项、false）；
返回super.onDependentViewChanged（父、子、依赖项）；
}
@凌驾
公共布尔onLayoutChild（CoordinatorLayoutParent、V-child、int-layoutDirection）{
布尔layoutChild=super.onLayoutChild（父、子、layoutDirection）；
if（mTabLayout==null&&mTabLayoutId！=View.NO\ID）{
mTabLayout=findTabLayout（子级）；
getAbsHolder（）；
}
返回下岗儿童；
}
@可空
私有视图组findTabLayout（@NonNull视图子级）{
如果（mTabLayoutId==0）返回null；
return（ViewGroup）child.findViewById（mTabLayoutId）；
}
@凌驾
public void onnestedvertialoverscroll（CoordinatorLayout CoordinatorLayout，V child，@ScrollDirection int direction，int currentOverScroll，int totalOverScroll）{
}
@凌驾
public void onDirectionNestedPreScroll（CoordinatorLayout CoordinatorLayout，V child，视图目标，int dx，int dy，int[]消耗，@ScrollDirection int ScrollDirection）{
handleDirection（子级、滚动方向）；
}
私有void handleDirection（V子级，@ScrollDirection int ScrollDirection）{
如果（！scrollingEnabled）返回；
if（scrollDirection==scrollDirection.SCROLL\u DIRECTION\u DOWN&&hidden）{
隐藏=错误；
动画偏移（子对象，0）；
}else if（scrollDirection==scrollDirection.SCROLL\u DIRECTION\u UP&&！hidden）{
隐藏=真实；
animateOffset（child，child.getHeight（））；
}
}
@凌驾
受保护的布尔值onNestedDirectionFling（CoordinatorLayout CoordinatorLayout，V子对象，视图目标，float velocityX，float velocityY，@ScrollDirection int ScrollDirection）{
handleDirection（子级、滚动方向）；
返回true；
}
私有void animateOffset（最终V子对象、最终int偏移）{
取消动画
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">


    <WebView
        android:id="@+id/webview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</RelativeLayout>

/*
 * Copyright (C) 2015 takahirom
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.github.takahirom.webview_in_coodinator_layout;

import android.content.Context;
import android.support.v4.view.MotionEventCompat;
import android.support.v4.view.NestedScrollingChild;
import android.support.v4.view.NestedScrollingChildHelper;
import android.support.v4.view.ViewCompat;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.webkit.WebView;

public class NestedWebView extends WebView implements NestedScrollingChild {
    private int mLastY;
    private final int[] mScrollOffset = new int[2];
    private final int[] mScrollConsumed = new int[2];
    private int mNestedOffsetY;
    private NestedScrollingChildHelper mChildHelper;

    public NestedWebView(Context context) {
        this(context, null);
    }

    public NestedWebView(Context context, AttributeSet attrs) {
        this(context, attrs, android.R.attr.webViewStyle);
    }

    public NestedWebView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        mChildHelper = new NestedScrollingChildHelper(this);
        setNestedScrollingEnabled(true);
    }

    @Override
    public boolean onTouchEvent(MotionEvent ev) {
        boolean returnValue = false;

        MotionEvent event = MotionEvent.obtain(ev);
        final int action = MotionEventCompat.getActionMasked(event);
        if (action == MotionEvent.ACTION_DOWN) {
            mNestedOffsetY = 0;
        }
        int eventY = (int) event.getY();
        event.offsetLocation(0, mNestedOffsetY);
        switch (action) {
            case MotionEvent.ACTION_MOVE:
                int deltaY = mLastY - eventY;
                // NestedPreScroll
                if (dispatchNestedPreScroll(0, deltaY, mScrollConsumed, mScrollOffset)) {
                    deltaY -= mScrollConsumed[1];
                    mLastY = eventY - mScrollOffset[1];
                    event.offsetLocation(0, -mScrollOffset[1]);
                    mNestedOffsetY += mScrollOffset[1];
                }
                returnValue = super.onTouchEvent(event);

                // NestedScroll
                if (dispatchNestedScroll(0, mScrollOffset[1], 0, deltaY, mScrollOffset)) {
                    event.offsetLocation(0, mScrollOffset[1]);
                    mNestedOffsetY += mScrollOffset[1];
                    mLastY -= mScrollOffset[1];
                }
                break;
            case MotionEvent.ACTION_DOWN:
                returnValue = super.onTouchEvent(event);
                mLastY = eventY;
                // start NestedScroll
                startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL);
                break;
            case MotionEvent.ACTION_UP:
            case MotionEvent.ACTION_CANCEL:
                returnValue = super.onTouchEvent(event);
                // end NestedScroll
                stopNestedScroll();
                break;
        }
        return returnValue;
    }

    // Nested Scroll implements
    @Override
    public void setNestedScrollingEnabled(boolean enabled) {
        mChildHelper.setNestedScrollingEnabled(enabled);
    }

    @Override
    public boolean isNestedScrollingEnabled() {
        return mChildHelper.isNestedScrollingEnabled();
    }

    @Override
    public boolean startNestedScroll(int axes) {
        return mChildHelper.startNestedScroll(axes);
    }

    @Override
    public void stopNestedScroll() {
        mChildHelper.stopNestedScroll();
    }

    @Override
    public boolean hasNestedScrollingParent() {
        return mChildHelper.hasNestedScrollingParent();
    }

    @Override
    public boolean dispatchNestedScroll(int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed,
                                        int[] offsetInWindow) {
        return mChildHelper.dispatchNestedScroll(dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed, offsetInWindow);
    }

    @Override
    public boolean dispatchNestedPreScroll(int dx, int dy, int[] consumed, int[] offsetInWindow) {
        return mChildHelper.dispatchNestedPreScroll(dx, dy, consumed, offsetInWindow);
    }

    @Override
    public boolean dispatchNestedFling(float velocityX, float velocityY, boolean consumed) {
        return mChildHelper.dispatchNestedFling(velocityX, velocityY, consumed);
    }

    @Override
    public boolean dispatchNestedPreFling(float velocityX, float velocityY) {
        return mChildHelper.dispatchNestedPreFling(velocityX, velocityY);
    }

}

<my.package.NestedWebView
    android:id="@+id/webview"
    android:layout_width="match_parent"
    android:layout_height="match_parent"/>

public final class BottomNavigationBehavior<V extends View> extends VerticalScrollingBehavior<V> {
    private static final Interpolator INTERPOLATOR = new LinearOutSlowInInterpolator();
    private final BottomNavigationWithSnackbar mWithSnackBarImpl = Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP ? new LollipopBottomNavWithSnackBarImpl() : new PreLollipopBottomNavWithSnackBarImpl();
    private boolean isTablet;
    private int mTabLayoutId;
    private boolean hidden = false;
    private ViewPropertyAnimatorCompat mOffsetValueAnimator;
    private ViewGroup mTabLayout;
    private View mTabsHolder;
    private int mSnackbarHeight = -1;
    private boolean scrollingEnabled = true;
    private boolean hideAlongSnackbar = false;
    int[] attrsArray = new int[] {
            android.R.attr.id };
    public BottomNavigationBehavior() {
        super();
    }

    public BottomNavigationBehavior(Context context, AttributeSet attrs) {
        super(context, attrs);
        TypedArray a = context.obtainStyledAttributes(attrs,
                attrsArray);
        mTabLayoutId = a.getResourceId(0, View.NO_ID);
        a.recycle();
    }

    public static <V extends View> BottomNavigationBehavior<V> from(@NonNull V view) {
        ViewGroup.LayoutParams params = view.getLayoutParams();
        if (!(params instanceof CoordinatorLayout.LayoutParams)) {
            throw new IllegalArgumentException("The view is not a child of CoordinatorLayout");
        }
        CoordinatorLayout.Behavior behavior = ((CoordinatorLayout.LayoutParams) params)
                .getBehavior();
        if (!(behavior instanceof BottomNavigationBehavior)) {
            throw new IllegalArgumentException(
                    "The view is not associated with BottomNavigationBehavior");
        }
        return (BottomNavigationBehavior<V>) behavior;
    }

    @Override
    public boolean layoutDependsOn(CoordinatorLayout parent, V child, View dependency) {
        mWithSnackBarImpl.updateSnackbar(parent, dependency, child);
        return dependency instanceof Snackbar.SnackbarLayout;
    }

    @Override
    public void onDependentViewRemoved(CoordinatorLayout parent, V child, View dependency) {
        updateScrollingForSnackbar(dependency, child, true);
        super.onDependentViewRemoved(parent, child, dependency);
    }

    private void updateScrollingForSnackbar(View dependency, V child, boolean enabled) {
        if (!isTablet && dependency instanceof Snackbar.SnackbarLayout) {
            scrollingEnabled = enabled;
            if (!hideAlongSnackbar && ViewCompat.getTranslationY(child) != 0) {
                ViewCompat.setTranslationY(child, 0);
                hidden = false;
                hideAlongSnackbar = true;
            }else if(hideAlongSnackbar){
                hidden = true;
                animateOffset(child, -child.getHeight());
            }
        }
    }

    @Override
    public boolean onDependentViewChanged(CoordinatorLayout parent, V child, View dependency) {
        updateScrollingForSnackbar(dependency, child, false);
        return super.onDependentViewChanged(parent, child, dependency);
    }

    @Override
    public boolean onLayoutChild(CoordinatorLayout parent, V child, int layoutDirection) {
        boolean layoutChild = super.onLayoutChild(parent, child, layoutDirection);
        if (mTabLayout == null && mTabLayoutId != View.NO_ID) {
            mTabLayout = findTabLayout(child);
            getTabsHolder();
        }

        return layoutChild;
    }

    @Nullable
    private ViewGroup findTabLayout(@NonNull View child) {
        if (mTabLayoutId == 0) return null;
        return (ViewGroup) child.findViewById(mTabLayoutId);
    }

    @Override
    public void onNestedVerticalOverScroll(CoordinatorLayout coordinatorLayout, V child, @ScrollDirection int direction, int currentOverScroll, int totalOverScroll) {
    }

    @Override
    public void onDirectionNestedPreScroll(CoordinatorLayout coordinatorLayout, V child, View target, int dx, int dy, int[] consumed, @ScrollDirection int scrollDirection) {
        handleDirection(child, scrollDirection);
    }

    private void handleDirection(V child, @ScrollDirection int scrollDirection) {
        if (!scrollingEnabled) return;
        if (scrollDirection == ScrollDirection.SCROLL_DIRECTION_DOWN && hidden) {
            hidden = false;
            animateOffset(child, 0);
        } else if (scrollDirection == ScrollDirection.SCROLL_DIRECTION_UP && !hidden) {
            hidden = true;
            animateOffset(child, child.getHeight());
        }
    }

    @Override
    protected boolean onNestedDirectionFling(CoordinatorLayout coordinatorLayout, V child, View target, float velocityX, float velocityY, @ScrollDirection int scrollDirection) {
        handleDirection(child, scrollDirection);
        return true;
    }

    private void animateOffset(final V child, final int offset) {
        ensureOrCancelAnimator(child);
        mOffsetValueAnimator.translationY(offset).start();
        animateTabsHolder(offset);
    }

    private void animateTabsHolder(int offset) {
        if (mTabsHolder != null) {
            offset = offset > 0 ? 0 : 1;
            ViewCompat.animate(mTabsHolder).alpha(offset).setDuration(200).start();
        }
    }

    private void ensureOrCancelAnimator(V child) {
        if (mOffsetValueAnimator == null) {
            mOffsetValueAnimator = ViewCompat.animate(child);
            mOffsetValueAnimator.setDuration(100);
            mOffsetValueAnimator.setInterpolator(INTERPOLATOR);
        } else {
            mOffsetValueAnimator.cancel();
        }
    }

    private void getTabsHolder() {
        if (mTabLayout != null) {
            mTabsHolder = mTabLayout.getChildAt(0);
        }
    }

    public boolean isScrollingEnabled() {
        return scrollingEnabled;
    }

    public void setScrollingEnabled(boolean scrollingEnabled) {
        this.scrollingEnabled = scrollingEnabled;
    }

    public void setHidden(V view, boolean bottomLayoutHidden) {
        if (!bottomLayoutHidden && hidden) {
            animateOffset(view, 0);
        } else if (bottomLayoutHidden && !hidden) {
            animateOffset(view, -view.getHeight());
        }
        hidden = bottomLayoutHidden;
    }

    private interface BottomNavigationWithSnackbar {
        void updateSnackbar(CoordinatorLayout parent, View dependency, View child);
    }

    private class PreLollipopBottomNavWithSnackBarImpl implements BottomNavigationWithSnackbar {

        @Override
        public void updateSnackbar(CoordinatorLayout parent, View dependency, View child) {
            if (!isTablet && dependency instanceof Snackbar.SnackbarLayout) {
                if (mSnackbarHeight == -1) {
                    mSnackbarHeight = dependency.getHeight();
                }

                int targetPadding = child.getMeasuredHeight();

                int shadow = (int) ViewCompat.getElevation(child);
                ViewGroup.MarginLayoutParams layoutParams = (ViewGroup.MarginLayoutParams) dependency.getLayoutParams();
                layoutParams.bottomMargin = targetPadding - shadow;
                child.bringToFront();
                if (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT) {
                    child.getParent().requestLayout();
                    ((View) child.getParent()).invalidate();
                }

            }
        }
    }

    private class LollipopBottomNavWithSnackBarImpl implements BottomNavigationWithSnackbar {

        @Override
        public void updateSnackbar(CoordinatorLayout parent, View dependency, View child) {
            if (!isTablet && dependency instanceof Snackbar.SnackbarLayout) {
                if (mSnackbarHeight == -1) {
                    mSnackbarHeight = dependency.getHeight();
                }
                int targetPadding = (mSnackbarHeight + child.getMeasuredHeight());
                dependency.setPadding(dependency.getPaddingLeft(),
                        dependency.getPaddingTop(), dependency.getPaddingRight(), targetPadding
                );
            }
        }
    }

<com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/nav_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="?android:attr/windowBackground"
        android:layout_gravity="bottom"
        app:itemIconTint="@color/bnv_selector"
        app:itemTextColor="@color/bnv_selector"
        app:labelVisibilityMode="labeled"
        app:layout_behavior="com.degoo.android.ui.progress.bottombehavior.ProgressBottomSheetBehaviour"
        app:menu="@menu/bottom_nav_menu"
/>