How do I remove the bouncing effect on appbar?

问题

Appbar used to have an issue when flinging. It was not scrolling smoothly.

Please refer to these:

• http://stackoverflow.com/questions/30923889/flinging-with-recyclerview-appbarlayout
• https://code.google.com/p/android/issues/detail?id=177729&q=appbarlayout&colspec=ID%20Type%20Status%20Owner%20Summary%20Stars
• https://github.com/henrytao-me/smooth-app-bar-layout

But it has been fixed in support library version 26.

compile 'com.android.support:design:26.0.0'

However, appbar is now bouncing back even if fling is not hard.

How do I remove this behavior?

回答1:

This is only happening when AppBar is scrolled/flung while the NestedScrollView(or RecyclerView) has not yet finish flinging.

Solution: Extend AppBar's default Behavior and block the call for AppBar.Behavior's onNestedPreScroll() and onNestedScroll() when AppBar is touched while NestedScroll hasn't stopped yet.

 @Override
public void onNestedPreScroll(CoordinatorLayout coordinatorLayout, AppBarLayout child, View target, int dx, int dy, int[] consumed, int type) {
    if (type == TYPE_FLING) {
        isFlinging = true;
    }
    if (!shouldBlockNestedScroll) {
        super.onNestedPreScroll(coordinatorLayout, child, target, dx, dy, consumed, type);
    }
}

@Override
public void onNestedScroll(CoordinatorLayout coordinatorLayout, AppBarLayout child, View target, int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed, int type) {
    if (!shouldBlockNestedScroll) {
        super.onNestedScroll(coordinatorLayout, child, target, dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed, type);
    }
}

then use it on the layout:

<android.support.design.widget.AppBarLayout
    android:id="@+id/app_bar"
    ...
    app:layout_behavior="com.mypackage.NoBounceBehavior"/>

Reference for full code of the custom behavior can be found here: https://gist.github.com/ampatron/9d56ea401094f67196f407f82f14551a

来源：https://stackoverflow.com/questions/47152764/how-do-i-remove-the-bouncing-effect-on-appbar