How to implement hiding the toolbar when scrolling WebView?

Question

I have an Activity with WebView and my own AppBarLayout. I want to implement hiding/showing the AppBarLayout with animation when scrolling the WebView, like in the Google Chrome app. I tried different ways. ObservableWebView, but it doesn't work correctly, it doesn't always show AppBar, especially if the page is short. ConstraintLayout with animations. Something similar, but still not the same

Accepted Answer

I created WebView with this features and it works perfect: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);    }}

Advertisement

Answer