private void changePage(int position, SliderItem item) {
mIgnoreBackStack = true;
if (mCurrentPage >= 0) {
final SliderItem lastItem = mAdapter.getItem(mCurrentPage);
final WeakReference<Fragment> ref = lastItem.mLastFragment;
final Fragment fragment = ref == null ? null : ref.get();
if (fragment != null && fragment.isAdded() && lastItem.mSaveState) {
if (!fragment.isDetached()) {
mFragmentManager.beginTransaction().detach(fragment).commit();
mFragmentManager.executePendingTransactions();
}
lastItem.mSavedState = mFragmentManager.saveFragmentInstanceState(fragment);
}
}
mCurrentPage = position;
mAdapter.notifyDataSetInvalidated();
while (mFragmentManager.popBackStackImmediate()) {}
final Fragment fragment = Fragment.instantiate(item.mFragmentClass);
if (item.mSavedState != null) {
fragment.setInitialSavedState(item.mSavedState);
}
item.mLastFragment = new WeakReference<Fragment>(fragment);
replaceFragment(mFragmentManager, fragment);
mIgnoreBackStack = false;
}
@Override
public void onBackStackChanged() {
if (mIgnoreBackStack || mCurrentPage < 0 || mCurrentPage >= mItems.size()) {
return;
}
SliderItem item = mItems.get(mCurrentPage);
WeakReference<Fragment> ref = item.mLastFragment;
Fragment fragment = ref == null ? null : ref.get();
if (fragment == null || !item.mSaveState) {
return;
}
if (fragment.isAdded() && fragment.isDetached() && !fragment.isVisible()) {
item.mSavedState = mFragmentManager.saveFragmentInstanceState(fragment);
}
}