package com.crossbowffs.nekosms.widget; import android.app.Fragment; import android.app.FragmentManager; import android.app.FragmentTransaction; import androidx.viewpager.widget.PagerAdapter; import android.view.View; import android.view.ViewGroup; /** * An implementation of the support library FragmentPagerAdapter * class for the native Android {@link Fragment} class. */ public abstract class FragmentPagerAdapter extends PagerAdapter { private final FragmentManager mFragmentManager; private FragmentTransaction mCurTransaction; private Fragment mCurrentPrimaryItem; public FragmentPagerAdapter(FragmentManager fragmentManager) { mFragmentManager = fragmentManager; } public abstract Fragment getItem(int position); @Override public Object instantiateItem(ViewGroup container, int position) { if (mCurTransaction == null) { mCurTransaction = mFragmentManager.beginTransaction(); } String name = makeFragmentName(container.getId(), position); Fragment fragment = mFragmentManager.findFragmentByTag(name); if (fragment != null) { mCurTransaction.attach(fragment); } else { fragment = getItem(position); mCurTransaction.add(container.getId(), fragment, name); } if (fragment != mCurrentPrimaryItem) { fragment.setMenuVisibility(false); fragment.setUserVisibleHint(false); } return fragment; } @Override public void destroyItem(ViewGroup container, int position, Object object) { if (mCurTransaction == null) { mCurTransaction = mFragmentManager.beginTransaction(); } mCurTransaction.detach((Fragment)object); } @Override public void setPrimaryItem(ViewGroup container, int position, Object object) { Fragment fragment = (Fragment)object; if (fragment != mCurrentPrimaryItem) { if (mCurrentPrimaryItem != null) { mCurrentPrimaryItem.setMenuVisibility(false); mCurrentPrimaryItem.setUserVisibleHint(false); } if (fragment != null) { fragment.setMenuVisibility(true); fragment.setUserVisibleHint(true); } mCurrentPrimaryItem = fragment; } } @Override public void finishUpdate(ViewGroup container) { if (mCurTransaction != null) { mCurTransaction.commitAllowingStateLoss(); mCurTransaction = null; mFragmentManager.executePendingTransactions(); } } @Override public boolean isViewFromObject(View view, Object object) { return ((Fragment)object).getView() == view; } private static String makeFragmentName(int viewId, long id) { return "android:switcher:" + viewId + ":" + id; } }