为BottomNavigationView 尝试自定义滚动行为，它允许您在滚动期间隐藏它。
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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
);
}
}
}
}
在你的视图中应用它：
<android.support.design.widget.BottomNavigationView
android:id="@+id/bottom_navigation"
android:layout_gravity="bottom"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
app:itemBackground="@color/colorPrimary"
app:itemIconTint="@color/white"
app:itemTextColor="@color/white"
app:layout_behavior=".BottomNavigationBehavior" //apply the behaviour
app:menu="@menu/bottom_navigation_main" />
输出：