@Override
public void showGuideView() {
    mViewPager.setVisibility(View.VISIBLE);
    List<View> viewList = new ArrayList<>();
    viewList.add(ViewUtil.inflateViewById(this, R.layout.layout_guide1));
    viewList.add(ViewUtil.inflateViewById(this, R.layout.layout_guide2));
    View lastView = ViewUtil.inflateViewById(this, R.layout.layout_guide3);
    TextView enter = lastView.findViewById(R.id.id_guide_enter_btn);
    enter.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            mSplashPresenter.enter();
        }
    });
    viewList.add(lastView);
    PagerAdapter vpAdapter = new GuideAdapter(viewList);
    mViewPager.setAdapter(vpAdapter);
    mIndicator.setViewPager(mViewPager, viewList.size());
}
 

public void notifyDataSetChanged() {
    mTabLayout.removeAllViews();
    PagerAdapter adapter = mViewPager.getAdapter();
    IconPagerAdapter iconAdapter = null;
    if (adapter instanceof IconPagerAdapter) {
        iconAdapter = (IconPagerAdapter)adapter;
    }
    final int count = adapter.getCount();
    for (int i = 0; i < count; i++) {
        CharSequence title = adapter.getPageTitle(i);
        if (title == null) {
            title = EMPTY_TITLE;
        }
        int iconResId = 0;
        if (iconAdapter != null) {
            iconResId = iconAdapter.getIconResId(i);
        }
        addTab(i, title, iconResId);
    }
    if (mSelectedTabIndex > count) {
        mSelectedTabIndex = count - 1;
    }
    setCurrentItem(mSelectedTabIndex);
    requestLayout();
}
 

@Override
public void setViewPager(ViewPager view) {
    if (mViewPager == view) {
        return;
    }
    if (mViewPager != null) {
        mViewPager.setOnPageChangeListener(null);
    }
    PagerAdapter adapter = view.getAdapter();
    if (adapter == null) {
        throw new IllegalStateException("ViewPager does not have adapter instance.");
    }
    mViewPager = view;
    view.setOnPageChangeListener(this);
    notifyDataSetChanged();
}
 

protected void setupTabView() {
    final LayoutInflater inflater = LayoutInflater.from(this);
    final int[] tabIcons = {R.drawable.ic_recommended, R.drawable.ic_topics, R.drawable.ic_wiki, R.drawable.ic_me};
    FragmentPagerItems pages = FragmentPagerItems.with(this)
            .add(R.string.recommended, RecommendedFragment.class)
            .add(R.string.topics, TopicsFragment.class)
            .add(R.string.wiki, WikiFragment.class)
            .add(R.string.me, MeFragment.class)
            .create();
    FragmentPagerItemAdapter adapter = new FragmentPagerItemAdapter(
            getSupportFragmentManager(),
            pages);

    viewPager.setOffscreenPageLimit(pages.size());
    viewPager.setAdapter(adapter);
    viewpagerTab.setCustomTabView(new SmartTabLayout.TabProvider() {
        @Override
        public View createTabView(ViewGroup container, int position, PagerAdapter pagerAdapter) {
            View view = inflater.inflate(R.layout.custom_tab_icon, container, false);
            ImageView iconView = (ImageView) view.findViewById(R.id.iv_icon);
            iconView.setBackgroundResource(tabIcons[position % tabIcons.length]);
            return view;
        }
    });
    viewpagerTab.setViewPager(viewPager);
}
 

private void scrollOnce() {
    PagerAdapter adapter = getAdapter();
    int currentItem = getCurrentItem();
    int count;
    if (adapter == null || (count = adapter.getCount()) < 1) {
        stopAutoScroll();
        return;
    }
    if (currentItem < count) {
        currentItem++;
    }
    if (currentItem == count) {
        currentItem = 0;
    }
    L.i(TAG, "currentItem : " + currentItem);
    setCurrentItem(currentItem);
}
 

/**
 * 将back事件分发给ViewPager中的Fragment,{@link #handleBackPress(FragmentManager)} 已经实现了对ViewPager的支持，所以自行决定是否使用该方法
 *
 * @return 如果处理了back键则返回 <b>true</b>
 * @see #handleBackPress(FragmentManager)
 * @see #handleBackPress(Fragment)
 * @see #handleBackPress(FragmentActivity)
 */
public static boolean handleBackPress(ViewPager viewPager) {
    if (viewPager == null) return false;

    PagerAdapter adapter = viewPager.getAdapter();

    if (adapter == null) return false;

    int currentItem = viewPager.getCurrentItem();
    Fragment fragment;
    if (adapter instanceof FragmentPagerAdapter) {
        fragment = ((FragmentPagerAdapter) adapter).getItem(currentItem);
    } else if (adapter instanceof FragmentStatePagerAdapter) {
        fragment = ((FragmentStatePagerAdapter) adapter).getItem(currentItem);
    } else {
        fragment = null;
    }
    return isFragmentBackHandled(fragment);
}
 

@Override
protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_earthquake_main);
  Toolbar toolbar = findViewById(R.id.toolbar);
  setSupportActionBar(toolbar);

  ViewPager viewPager = findViewById(R.id.view_pager);
  if (viewPager != null) {
    PagerAdapter pagerAdapter =
      new EarthquakeTabsPagerAdapter(getSupportFragmentManager());
    viewPager.setAdapter(pagerAdapter);
    TabLayout tabLayout = findViewById(R.id.tab_layout);
    tabLayout.setupWithViewPager(viewPager);
  }

  // Retrieve the Earthquake View Model for this Activity.
  earthquakeViewModel = ViewModelProviders.of(this)
                          .get(EarthquakeViewModel.class);
}
 

public void setViewPager(ViewPager viewPager) {
    if (viewPager == null) {
        tabsContainer.removeAllViews();
        if (this.viewPager != null) {
            this.viewPager.removeOnAdapterChangeListener(adapterChangeListener);
            this.viewPager.removeOnPageChangeListener(this);
        }
        this.viewPager = viewPager;
        return;
    }
    this.viewPager = viewPager;
    this.viewPager.addOnPageChangeListener(this);
    adapterChangeListener = new ViewPager.OnAdapterChangeListener() {
        @Override
        public void onAdapterChanged(@NonNull ViewPager viewPager, @Nullable PagerAdapter oldAdapter, @Nullable PagerAdapter newAdapter) {
            listenToAdapterChanges(newAdapter);
        }
    };
    viewPager.addOnAdapterChangeListener(adapterChangeListener);

    listenToAdapterChanges(viewPager.getAdapter());
}
 

public void setAdapter(PagerAdapter pagerAdapter) {
    if (mIndicatorPathList.size() > 0) mIndicatorPathList.clear();
    if (mCirclePaths.size() > 0) mCirclePaths.clear();
    if (null != pagerAdapter) {
        this.mPagerAdapter = pagerAdapter;
    }
    if (mHeight != 0) {
        this.mIndicatorCount = mPagerAdapter.getCount();
        for (int i = 0; i < mIndicatorCount; i++) {
            Indicator indicator = generateIndicator(i);
            Path path = calculateUnderHalfPath(indicator);
            mCirclePaths.add(path);
            mDefaultIndicatorList.add(indicator);
        }
        mCurrentPath = mCirclePaths.get(0);
        requestLayout();
        invalidate();
    }
}
 

@Override
public void setViewPager(ViewPager view) {
    if (mViewPager == view) {
        return;
    }
    if (mViewPager != null) {
        mViewPager.setOnPageChangeListener(null);
    }
    PagerAdapter adapter = view.getAdapter();
    if (adapter == null) {
        throw new IllegalStateException("ViewPager does not have adapter instance.");
    }
    mViewPager = view;
    view.setOnPageChangeListener(this);
    notifyDataSetChanged();
}
 

@Override
public void notifyDataSetChanged() {
    mTabLayout.removeAllViews();
    PagerAdapter adapter = mViewPager.getAdapter();
    IconPagerAdapter iconAdapter = null;
    if (adapter instanceof IconPagerAdapter) {
        iconAdapter = (IconPagerAdapter)adapter;
    }
    final int count = adapter.getCount();
    for (int i = 0; i < count; i++) {
        CharSequence title = adapter.getPageTitle(i);
        if (title == null) {
            title = EMPTY_TITLE;
        }
        int iconResId = 0;
        if (iconAdapter != null) {
            iconResId = iconAdapter.getIconResId(i);
        }
        addTab(i, title, iconResId);
    }
    if (mSelectedTabIndex > count) {
        mSelectedTabIndex = count - 1;
    }
    setCurrentItem(mSelectedTabIndex);
    requestLayout();
}
 

@Override
public void setViewPager(ViewPager view) {
    if (mViewPager == view) {
        return;
    }
    if (mViewPager != null) {
        mViewPager.setOnPageChangeListener(null);
    }
    final PagerAdapter adapter = view.getAdapter();
    if (adapter == null) {
        throw new IllegalStateException("ViewPager does not have adapter instance.");
    }
    mViewPager = view;
    view.setOnPageChangeListener(this);
    notifyDataSetChanged();
}
 

private ObservableRecyclerView findRecyclerViewFrom(final int position) {
    final PagerAdapter adapter = getAdapter();
    if (adapter instanceof ContainRecyclerViewPagerAdapter) {
        return ((ContainRecyclerViewPagerAdapter) adapter).getRecyclerView(position);
    }
    return null;
}
 

public void notifyDataSetChanged() {
    PagerAdapter adapter = this.mViewPager.getAdapter();
    int count = adapter.getCount();
    if (count != 0) {
        int width = TAB_MARGIN;
        for (int i = 0; i < count; i++) {
            width += getTabWidth(adapter.getPageTitle(i)) + TAB_MARGIN;
        }
        this.mMeanWidth = -1;
        if (this.mLayoutWidth > width && count <= 7) {
            this.mMeanWidth = this.mLayoutWidth / count;
        }
        super.notifyDataSetChanged();
    }
}
 

@Override
public void setAdapter(PagerAdapter adapter) {
    if (wrappedPagerAdapter != null && mObserver != null) {
        wrappedPagerAdapter.unregisterDataSetObserver(mObserver);
    }
    wrappedPagerAdapter = adapter;
    if (wrappedPagerAdapter != null && mObserver != null) {
        wrappedPagerAdapter.registerDataSetObserver(mObserver);
    }
    wrapperPagerAdapter = (wrappedPagerAdapter == null) ? null : new AutoScrollPagerAdapter(adapter);
    super.setAdapter(wrapperPagerAdapter);

    setCurrentItem(0, false);
}
 

public View findViewFromObject(int position) {
    Object o = mObjs.get(Integer.valueOf(position));
    if (o == null) {
        return null;
    }
    PagerAdapter a = getAdapter();
    View v;
    for (int i = 0; i < getChildCount(); i++) {
        v = getChildAt(i);
        if (a.isViewFromObject(v, o))
            return v;
    }
    return null;
}
 

protected void inflateAdapter(PagerAdapter pagerAdapter) {
    if (mViewPager.getAdapter() == null) {
        setAdapterAndTabLayout(pagerAdapter);
    } else {
        PagerAdapter currentAdapter = mViewPager.getAdapter();
        Class adapterClass = currentAdapter.getClass();
        if (!adapterClass.equals(pagerAdapter.getClass())) {
            setAdapterAndTabLayout(pagerAdapter);
        } else {
            String message = pagerAdapter.getClass().getName() + " is already visible";
            Timber.d(message);
        }
    }
}
 

private void populateTabStrip() {
    final PagerAdapter adapter = mViewPager.getAdapter();
    final OnClickListener tabClickListener = new TabClickListener();

    for (int i = 0; i < adapter.getCount(); i++) {
        View tabView = null;

        TabItemSpec tabItem;
        if (this.mTabItems != null && this.mTabItems.length > i) {
            tabItem = this.mTabItems[i];
        } else {
            tabItem = new TabItemSpec();
            tabItem.title = adapter.getPageTitle(i).toString();
        }

        tabView = createDefaultTabView(getContext(), tabItem);

        tabView.setOnClickListener(tabClickListener);
        String desc = mContentDescriptions.get(i, null);
        if (desc != null) {
            tabView.setContentDescription(desc);
        }

        mTabStrip.addView(tabView);
        if (i == mViewPager.getCurrentItem()) {
            tabView.setSelected(true);
        }
    }
}
 

@Override
public int getItemPosition(Object o) {
    Integer result = positionDelta.get(o);

    if (result == null) {
        return (PagerAdapter.POSITION_UNCHANGED);
    }

    return (result);
}
 

/**
 * pager的adapter
 *
 * @param mAdapter
 * @return
 */
public ExtViewQuery adapter(final PagerAdapter mAdapter) {
    if (view instanceof ViewPager) {
        ((ViewPager) view).setAdapter(mAdapter);
    }
    return self();
}
 

private void populateTabLayout() {
    final PagerAdapter adapter = mViewPager.getAdapter();
    final OnClickListener tabClickListener = new TabClickListener();
    mIconLayouts = new View[adapter.getCount()];

    for (int i = 0; i < adapter.getCount(); i++) {

        final View tabView = LayoutInflater.from(getContext()).inflate(R.layout.layout_mainbottom_tab, this, false);
        mIconLayouts[i] = tabView;
        TabIconView iconView = (TabIconView) tabView.findViewById(R.id.main_bottom_tab_icon);
        iconView.init(mIconRes[i][0], mIconRes[i][1]);
        TextView textView = (TextView) tabView.findViewById(R.id.main_bottom_tab_text);
        textView.setText(mTitles[i]);

        if (tabView == null) {
            throw new IllegalStateException("tabView is null.");
        }

        LayoutParams lp = (LayoutParams) tabView.getLayoutParams();
        lp.width = 0;
        lp.weight = 1;

        tabView.setOnClickListener(tabClickListener);
        addView(tabView);

        if (i == mViewPager.getCurrentItem()) {
            iconView.transformPage(0);
            tabView.setSelected(true);
            textView.setTextColor(mTextSelectedColor);
        }
    }
}
 

private SliderAdapter getRealAdapter() {
    PagerAdapter adapter = mViewPager.getAdapter();
    if (adapter != null) {
        return ((InfinitePagerAdapter) adapter).getRealAdapter();
    }
    return null;
}
 

/**
 * clear self means unregister the dataset observer and remove all the child views(indicators).
 */
public void destroySelf(){
    if(mPager == null || mPager.getAdapter() == null){
        return;
    }
    InfinitePagerAdapter wrapper = (InfinitePagerAdapter)mPager.getAdapter();
    PagerAdapter adapter = wrapper.getRealAdapter();
    if(adapter!=null){
        adapter.unregisterDataSetObserver(dataChangeObserver);
    }
    removeAllViews();
}
 

@Override protected void populateTabStrip() {
    final PagerAdapter adapter = viewPager.getAdapter();
    if (adapter == null) {
        return;
    }
    for (int i = 0; i < adapter.getCount(); i++) {

        CharSequence title = adapter.getPageTitle(i);
        final View tabView = (tabProvider == null) ? createDefaultTabView(title)
                : tabProvider.createTabView(tabStrip, i, title);
        if (tabView == null) {
            throw new IllegalStateException("tabView is null.");
        }
        if (distributeEvenly) {
            LinearLayout.LayoutParams lp =
                    (LinearLayout.LayoutParams) tabView.getLayoutParams();
            lp.width = 0;
            lp.weight = 1;
        }

        if (internalTabClickListener != null) {
            tabView.setOnClickListener(internalTabClickListener);
        }

        tabStrip.addView(tabView);

        if (i == getCurrentItem()) {
            tabView.setSelected(true);
        }
    }
}
 

@Override
public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.app_bar_tabs);

  ViewPager viewPager = findViewById(R.id.view_pager);
  PagerAdapter pagerAdapter =
    new FixedTabsPagerAdapter(getSupportFragmentManager());
  viewPager.setAdapter(pagerAdapter);

  TabLayout tabLayout = findViewById(R.id.tab_layout);
  tabLayout.setupWithViewPager(viewPager);
}
 

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    getTheme().applyStyle(new FontPreferences(this).getCommentFontStyle().getResId(), true);
    getTheme().applyStyle(new FontPreferences(this).getPostFontStyle().getResId(), true);

    getTheme().applyStyle(new ColorPreferences(this).getFontStyle().getBaseId(), true);

    setContentView(R.layout.activity_tutorial);


    // Instantiate a ViewPager and a PagerAdapter.
    mPager = findViewById(R.id.vp);
    /*
  The pager adapter, which provides the pages to the view pager widget.
 */
    PagerAdapter mPagerAdapter = new ScreenSlidePagerAdapter(getSupportFragmentManager());
    mPager.setAdapter(mPagerAdapter);

    if(getIntent().hasExtra("page")){
        mPager.setCurrentItem(1);
    }

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
        Window window = this.getWindow();
        window.clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
        window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
        window.setStatusBarColor(Palette.getDarkerColor(Color.parseColor("#FF5252")));
    }

}
 

@Override
public void setAdapter(PagerAdapter adapter) {
    mAdapter = new LoopPagerAdapterWrapper(adapter);
    mAdapter.setBoundaryCaching(mBoundaryCaching);
    super.setAdapter(mAdapter);
    setCurrentItem(0, false);
}
 

private void setAdapter(final PagerAdapter adapter) {
    viewPager.setOffscreenPageLimit(adapter.getCount() - 1);
    viewPager.setAdapter(adapter);
    CountEventHelper.countExploreTab(getContext(),
            adapter.getPageTitle(viewPager.getCurrentItem()).toString());
    viewPager.addOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
        @Override
        public void onPageSelected(int position) {
            CountEventHelper.countExploreTab(getContext(),
                    adapter.getPageTitle(position).toString());
        }
    });
    tab.setupWithViewPager(viewPager);
}
 

protected PagerAdapter getPageAdapter(String initValue) {
    if (Premium.isPremium(this)) {
        return new PagerSectionAdapterPro(this, getSupportFragmentManager(), initValue);
    } else {
        return new PagerSectionAdapter(this, getSupportFragmentManager(), initValue);
    }
}
 

@BindingAdapter(value = {"fragments", "curIndex"}, requireAll = false)
public static void bind(ViewPager container, final List<? extends Fragment> fragments, int curIndex) {
    if(!(container.getContext() instanceof FragmentActivity))
        throw new IllegalArgumentException(TAG + "context must instanceof FragmentActivity");
    FragmentManager fm = ((FragmentActivity) container.getContext()).getSupportFragmentManager();

    if (fragments != null && !fragments.isEmpty()) {
        PagerAdapter adapter = container.getAdapter();
        if(adapter == null) {
            // initialize, fragments are only added once !!!
            container.setAdapter(adapter = new FragmentPagerAdapter(fm) {
                @Override
                public Fragment getItem(int position) {
                    return fragments.get(position);
                }

                @Override
                public int getCount() {
                    return fragments.size();
                }
            });
        }

        adapter.notifyDataSetChanged();

        if(curIndex >= 0 && curIndex < fragments.size())
            container.setCurrentItem(curIndex);
    }
}