android - CoordinatorLayout/NestedScrollView/Hide-Show Toolbar/Issue with WebView

Question

I have a problem with that :

<?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"
    android:id="@+id/coordinatorLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appBarLayout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:layout_scrollFlags="scroll|enterAlways" />
    </android.support.design.widget.AppBarLayout>

    <android.support.v4.widget.NestedScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior">

        <WebView
            android:id="@+id/webView"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />
    </android.support.v4.widget.NestedScrollView>

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

When I scrolls in the webview, the toolbar is hidden or shown (perfect !) but there is a problem with the loading / positioning web pages. For example, if I scrolls to the middle of a page and I click on a link, the new page that will load also be located at approximately the middle of the page instead of on top. As if scrollbars were not moving from one page to another.

if I add to the NestedScrollView:

android:fillViewport="true"

everything works with the webview (pages load and appear well although starting from the top) but I lose the Hide/Show with the toolbar :(

Do you have any idea about this problem?

Thank you in advance for your help :)

(For information : Android Design Support Library : 23.0.1)

Yop

Answer 1

My assumption: Since you are putting the WebView inside a NestedScrollView the scrolling is not done on the WebView level so when you load a new page the NestedScrollView stays in the same position.

Suggestion: create a WebViewClient and override onPageStarted here you should change the NestedScrollView scroll position to 0:

nestedScrollView.scrollTo(0, 0);