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android - 处理滚动状态以在 Fragment 中隐藏 FAB

问题描述

我有一个与 ViewPager 绑定的 FAB，单击它会打开一个片段并隐藏 FAB，但是当我在片段内水平滚动时，FAB 会重新出现。所以我决定通过调用 addOnPageChangeListener 来处理 ViewPager 的滚动状态，并使用自定义 ViewPager 来设置滚动状态（setSwipeEnabled）。这就是问题。要么我让片段不滚动，但片段上的 ViewPager 也不会退出，或者我让按钮重新出现。我试图实现的条件是（如果 FAB 新打开的片段是 !null 不要滚动，否则滚动）。任何帮助表示赞赏！代码：

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    mViewPager = findViewById(R.id.viewPager);
    mViewPager.setSwipeEnabled(true);

    ...

    mFAB = findViewById(R.id.mainFab);

    mViewPager.addOnPageChangeListener(new CustomViewPager.OnPageChangeListener() {

        Fragment fragment = null;

        @Override
        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
        }

        @Override
        public void onPageSelected(final int position) {

            if(position == 2){
                mFAB.hide();
            }else{
                mFAB.show();
            }


            switch (position){
                case 0:
                    mFAB.setImageResource(R.drawable.ic_handshake_white_54dp);
                    mFAB.setOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(View view) {



                            mActionBar.setTitle("New Package");

                            mFAB.hide();

                            fragment = new AddPackageFragment();

                            mFragmentManager.beginTransaction().add(R.id.contentFrame,fragment).addToBackStack("HomeFrag").commit();

                            //Condition I can't get to work
                            if(fragment != null){
                                mViewPager.setSwipeEnabled(false);
                            }else{
                                mViewPager.setSwipeEnabled(true);
                            }

                        }

                    });

                    break;
                case 1:
                    mFAB.setImageResource(R.drawable.ic_mail_outline_24dp);
                    mFAB.setOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(View view) {

                            mFAB.hide();

                            mActionBar.setTitle("New Message");

                            fragment = new NewMessageFragment();

                            mFragmentManager.beginTransaction().add(R.id.contentFrame,fragment).addToBackStack(null).commit();

                        }
                    });
                    break;
                case 2:

                    mFAB.setOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(View view) {

                            fragment = new DialogEditRequestFragment();

                            mFragmentManager.beginTransaction().replace(R.id.contentFrame,fragment).addToBackStack(null).commit();

                        }
                    });
                    break;

            }

        }

        @Override
        public void onPageScrollStateChanged(int state) {
            //Animate fab
            if(state == SCROLL_STATE_DRAGGING){
                mFAB.hide();
            }

            if(state == SCROLL_STATE_SETTLING){
                mFAB.show();
            }
        }
    });

}

CustomViewPager

    public class CustomViewPager extends ViewPager {

private boolean swipePageEnabled;

public CustomViewPager(Context context, AttributeSet attrs) {
    super(context, attrs);
    this.swipePageEnabled = false; // By default swiping is disabled
}

@Override
public boolean onTouchEvent(MotionEvent event) {
    return this.swipePageEnabled && super.onTouchEvent(event);

}

@Override
public boolean onInterceptTouchEvent(MotionEvent event) {
    return this.swipePageEnabled && super.onInterceptTouchEvent(event);

}

@Override
public boolean executeKeyEvent(KeyEvent event) {
    return this.swipePageEnabled && super.executeKeyEvent(event);
}

public void setSwipeEnabled(boolean enabled) {
    this.swipePageEnabled = enabled;
}

public boolean isSwipeEnabled(){
    return swipePageEnabled;
}

标签： androidandroid-fragmentsandroid-viewpager

解决方案

所以我想通了！它只需要一个布尔接口来检查片段是否可见。听起来很简单，但有时你只需要睡觉。

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    @Override
public void onFragmentVisible(boolean isVisible) {
    if(!isVisible){
        mViewPager.setSwipeEnabled(true);
        mFAB.show();
    }
}

分段

    mCloseBtn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            mFragmentVisibilityListener.onFragmentVisible(false);
            mActionBarListener.onActionBarListener(R.string.app_name);
            getFragmentManager().popBackStack();
        }
    });

  @Override
public void onAttach(Context context) {
    super.onAttach(context);

    try{
        mFragmentVisibilityListener = (OnFragmentInteractionListener) context;
        mActionBarListener = (OnFragmentInteractionListener) context;
    }catch (ClassCastException e){
        throw new ClassCastException(context.toString() + "must implement OnFragmentInteraction Listener");
    }
}

    @Override
public void onDetach() {
    super.onDetach();
    mActionBarListener = null;
    mFragmentVisibilityListener = null;
}

界面

    public interface OnFragmentInteractionListener {

void onActionBarListener(int title);

void onFragmentVisible(boolean isVisible);

希望这对其他人有帮助！

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