Question

我在协调器布局中有5个选项卡布局。

我想只在第一个标签上显示fab图标，然后隐藏在其余标签上。

我试过这个和它的工作：

viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
            }

            @Override
            public void onPageSelected(int position) {

                switch (position) {
                    case 0:
                        fab.show();
                        break;

                    default:
                        fab.hide();
                        break;
                }
            }

            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });

问题是我还想要fab按钮的hide on scrolling效果。

所以我创建了一个ScrollAwareFABBehavior类，它扩展了FloatingActionButton.Behavior并将CoordinatorLayout行为关联到Floating Action Button

package com.simha.yatras;    
import android.content.Context;
import android.support.design.widget.CoordinatorLayout;
import android.support.design.widget.FloatingActionButton;
import android.support.v4.view.ViewCompat;
import android.util.AttributeSet;
import android.view.View;

public class ScrollAwareFABBehavior extends FloatingActionButton.Behavior {
    public ScrollAwareFABBehavior(Context context, AttributeSet attrs) {
        super();
    }

    @Override
    public boolean onStartNestedScroll(final CoordinatorLayout coordinatorLayout, final FloatingActionButton child,
                                       final View directTargetChild, final View target, final int nestedScrollAxes) {
        // Ensure we react to vertical scrolling
        return nestedScrollAxes == ViewCompat.SCROLL_AXIS_VERTICAL
                || super.onStartNestedScroll(coordinatorLayout, child, directTargetChild, target, nestedScrollAxes);
    }

    @Override
    public void onNestedScroll(final CoordinatorLayout coordinatorLayout, final FloatingActionButton child,
                               final View target, final int dxConsumed, final int dyConsumed,
                               final int dxUnconsumed, final int dyUnconsumed) {
        super.onNestedScroll(coordinatorLayout, child, target, dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed);

        if (dyConsumed > 0 && child.getVisibility() == View.VISIBLE) {
            // User scrolled down and the FAB is currently visible -> hide the FAB
            child.hide();
        } else if (dyConsumed < 0 && child.getVisibility() != View.VISIBLE) {
            // User scrolled up and the FAB is currently not visible -> show the FAB
            child.show();
        }
    }
}

并通过

实施

<android.support.design.widget.FloatingActionButton
.
.
app:layout_behavior="com.simha.yatras.ScrollAwareFABBehavior"/>

如果我从第一个标签看到任何标签，图标就会消失。（这就是我想要的）。但是如果我滚动那个标签内部，如果我在顶部，则图标可见，到达底部时消失。

它出现在所有标签中。

ScrollAwareFABBehavior正在对所有标签执行操作。如何限制它仅在第一个选项卡上起作用。

Answer 1

我明白了。我最近在stackoverflow上找到了解决方案。 Android - FAB to hide when navigating between different fragments in a viewpager

在MainActivity中将viewPager添加为静态，然后在滚动行为中添加

if (MainActivity.viewPager.getCurrentItem() == 0) {
        if (dyConsunmed > 0 && child.getVisibility() == View.VISIBLE ) {
            child.hide();
        } else if (dyConsunmed < 0 && child.getVisibility() != View.VISIBLE) {
            child.show();
        }

    }

android：仅在第一个选项卡上显示fab图标

1 个答案: