如何实现滚动WebView时隐藏工具栏?

Question

我有一个 Web View 和我自己的 AppBarLayout 的活动。 我想在滚动WebView时实现隐藏/显示带有动画的AppBarLayout，就像在Google Chrome应用程序中一样。

我尝试了不同的方法。

• 可观察的WebView，但它不能正常工作，它并不总是显示AppBar，尤其是在页面较短的情况下。

• 带有动画的约束布局。类似的东西，但仍然与谷歌浏览器中不同。

• 协调器布局。我认为这是最好的变体。但它有一些错误。

我像这样编写了布局代码：

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.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:id="@+id/main_content"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true">
<android.support.design.widget.AppBarLayout
android:id="@+id/appBar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">

<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="@android:color/white"
app:layout_scrollFlags="scroll|enterAlways">
<View
android:id="@+id/linkFrame"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/colorPrimary"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintTop_toTopOf="parent"
tools:visibility="visible" />
<HorizontalScrollView
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:background="@drawable/frame_link_browser"
android:padding="8dp"
app:layout_constraintBottom_toBottomOf="@+id/linkFrame"
app:layout_constraintEnd_toStartOf="@+id/pauseButton"
app:layout_constraintStart_toEndOf="@+id/linkDivider"
app:layout_constraintTop_toTopOf="@+id/linkFrame">
<TextView
android:id="@+id/linkTextView"
style="@style/BrowserSmallSecondaryText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:maxLines="1"
android:textColor="@color/textPrimary"
android:textIsSelectable="true"
tools:text="https://vk.com/id118573338"
tools:visibility="visible" />
</HorizontalScrollView>

<View
android:id="@+id/linkDivider"
style="@style/VerticalDivider"
android:layout_height="24dp"
android:layout_centerVertical="true"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:background="#90FFFFFF"
android:textColor="@color/textPrimary"
app:layout_constraintBottom_toBottomOf="@+id/timerTextView"
app:layout_constraintStart_toEndOf="@+id/timerTextView"
app:layout_constraintTop_toTopOf="@+id/timerTextView"
tools:visibility="visible" />
<TextView
android:id="@+id/timerTextView"
style="@style/BrowserMiddlePrimaryText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerVertical="true"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:gravity="center_vertical"
app:layout_constraintBottom_toBottomOf="@+id/linkFrame"
app:layout_constraintStart_toStartOf="@+id/linkFrame"
app:layout_constraintTop_toTopOf="@+id/linkFrame"
tools:text="30" />
<TextView
android:id="@+id/noInternetTextView"
style="@style/BrowserBigPrimaryText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginLeft="16dp"
android:text="@string/no_internet_connection"
android:visibility="gone"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/noInternetAdditionalTextView"
style="@style/BrowserSmallSecondaryText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/no_internet_connection_additional"
android:visibility="gone"
app:layout_constraintLeft_toLeftOf="@+id/noInternetTextView"
app:layout_constraintTop_toBottomOf="@+id/noInternetTextView" />
<ImageButton
android:id="@+id/pauseButton"
android:layout_width="44dp"
android:layout_height="44dp"
android:background="@color/transparent"
android:text="@string/pause"
app:layout_constraintBottom_toBottomOf="@+id/linkFrame"
app:layout_constraintEnd_toStartOf="@+id/settingsButton"
app:layout_constraintTop_toTopOf="@+id/linkFrame"
app:srcCompat="@drawable/ic_pause_circle_filled_white_36dp"
tools:visibility="visible" />
<ImageButton
android:id="@+id/settingsButton"
android:layout_width="44dp"
android:layout_height="44dp"
android:background="@color/transparent"
android:text="@string/settings"
app:layout_constraintBottom_toBottomOf="@+id/linkFrame"
app:layout_constraintEnd_toEndOf="@+id/linkFrame"
app:layout_constraintTop_toTopOf="@+id/linkFrame"
app:srcCompat="@drawable/ic_settings_white_36dp"
tools:visibility="visible" />
</android.support.constraint.ConstraintLayout>
</android.support.design.widget.AppBarLayout>

<android.support.v4.widget.SwipeRefreshLayout
android:id="@+id/swipeRefresh"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior">

<android.support.v4.widget.NestedScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fillViewport="true"
app:layout_behavior="@string/appbar_scrolling_view_behavior">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/white"
android:orientation="vertical">
<ProgressBar
android:id="@+id/progressBar"
style="?android:attr/progressBarStyleHorizontal"
android:layout_width="match_parent"
android:layout_height="4dp"
android:indeterminate="false"
android:max="100"
android:progress="0"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
<com.github.ksoichiro.android.observablescrollview.ObservableWebView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/webView"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>
</android.support.v4.widget.NestedScrollView>
</android.support.v4.widget.SwipeRefreshLayout>
</android.support.design.widget.CoordinatorLayout>

在这种情况下，页面不会滚动。我尝试了许多变体。如果在行为中我放置干净的 Web 视图(没有滑动刷新、嵌套滚动等)，它可以正常工作，但是如果我锁定并解锁屏幕 - WebView 膨胀并在页面底部出现白色空白位置。 几天来我一直在尝试解决这个问题，但它不起作用。请帮助解决此问题。谢谢。

我尝试了这种方法： 如何在Web视图中向下滚动时隐藏动作栏/工具栏，但是如果我锁定并解锁屏幕 - WebView膨胀并在页面底部出现白色空白位置

Answer 1

我用这个功能创建了 WebView，它工作得很好：

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.view.ViewGroup;
import android.webkit.WebView;
public class NestedWebView extends WebView implements NestedScrollingChild, Scrollable {
private int mLastY;
private final int[] mScrollOffset = new int[2];
private final int[] mScrollConsumed = new int[2];
private int mNestedOffsetY;
private NestedScrollingChildHelper mChildHelper;
private int mScrollY;
private ScrollViewCallback callback;
private boolean firstScroll = true;

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);
}
public void setOnScrollListener(ScrollViewCallback callback) {
this.callback = callback;
}
@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);
if (firstScroll) {
// dispatching first down scrolling properly by making sure that first deltaY will be -ve
mLastY = eventY - 5;
firstScroll = false;
} else {
mLastY = eventY;
}
// start NestedScroll
startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL);
break;
default:
returnValue = super.onTouchEvent(event);
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);
}

@Override
protected void onScrollChanged(int l, int t, int oldl, int oldt) {
super.onScrollChanged(l, t, oldl, oldt);
mScrollY = t;
dispatchOnScrollChanged(mScrollY);
}
private void dispatchOnScrollChanged(int scrollY) {
if (callback != null) {
callback.onScrollChanged(scrollY);
}
}
// Scrollable implements
@Override
public void setScrollViewCallbacks(ObservableScrollViewCallbacks listener) {
}
@Override
public void scrollVerticallyTo(int y) {
}
@Override
public int getCurrentScrollY() {
return mScrollY;
}
@Override
public void setTouchInterceptionViewGroup(ViewGroup viewGroup) {
}
public interface ScrollViewCallback {
void onScrollChanged(int scrollY);
}

}