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@@ -0,0 +1,179 @@
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+package eu.kanade.mangafeed.ui.main;
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+
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+import android.app.Activity;
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+import android.support.annotation.Nullable;
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+import android.support.v4.app.Fragment;
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+import android.support.v4.app.FragmentManager;
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+
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+import java.util.ArrayList;
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+import java.util.List;
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+
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+import eu.kanade.mangafeed.R;
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+
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+/**
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+ * Why this class is needed.
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+ *
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+ * FragmentManager does not supply a developer with a fragment stack.
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+ * It gives us a fragment *transaction* stack.
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+ *
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+ * To be sane, we need *fragment* stack.
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+ *
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+ * This implementation also handles NucleusSupportFragment presenter`s lifecycle correctly.
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+ */
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+public class FragmentStack {
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+
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+ public interface OnBackPressedHandlingFragment {
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+ boolean onBackPressed();
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+ }
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+
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+ public interface OnFragmentRemovedListener {
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+ void onFragmentRemoved(Fragment fragment);
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+ }
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+
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+ private Activity activity;
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+ private FragmentManager manager;
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+ private int containerId;
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+ @Nullable private OnFragmentRemovedListener onFragmentRemovedListener;
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+
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+ public FragmentStack(Activity activity, FragmentManager manager, int containerId, @Nullable OnFragmentRemovedListener onFragmentRemovedListener) {
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+ this.activity = activity;
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+ this.manager = manager;
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+ this.containerId = containerId;
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+ this.onFragmentRemovedListener = onFragmentRemovedListener;
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+ }
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+
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+ /**
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+ * Returns the number of fragments in the stack.
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+ *
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+ * @return the number of fragments in the stack.
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+ */
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+ public int size() {
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+ return getFragments().size();
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+ }
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+
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+ /**
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+ * Pushes a fragment to the top of the stack.
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+ */
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+ public void push(Fragment fragment) {
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+
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+ Fragment top = peek();
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+ if (top != null) {
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+ manager.beginTransaction()
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+ .setCustomAnimations(R.anim.enter_from_right, R.anim.exit_to_left, R.anim.enter_from_left, R.anim.exit_to_right)
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+ .remove(top)
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+ .add(containerId, fragment, indexToTag(manager.getBackStackEntryCount() + 1))
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+ .addToBackStack(null)
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+ .commit();
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+ }
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+ else {
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+ manager.beginTransaction()
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+ .add(containerId, fragment, indexToTag(0))
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+ .commit();
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+ }
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+
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+ manager.executePendingTransactions();
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+ }
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+
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+ /**
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+ * Pops the top item if the stack.
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+ * If the fragment implements {@link OnBackPressedHandlingFragment}, calls {@link OnBackPressedHandlingFragment#onBackPressed()} instead.
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+ * If {@link OnBackPressedHandlingFragment#onBackPressed()} returns false the fragment gets popped.
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+ *
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+ * @return true if a fragment has been popped or if {@link OnBackPressedHandlingFragment#onBackPressed()} returned true;
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+ */
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+ public boolean back() {
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+ Fragment top = peek();
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+ if (top instanceof OnBackPressedHandlingFragment) {
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+ if (((OnBackPressedHandlingFragment)top).onBackPressed())
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+ return true;
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+ }
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+ return pop();
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+ }
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+
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+ /**
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+ * Pops the topmost fragment from the stack.
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+ * The lowest fragment can't be popped, it can only be replaced.
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+ *
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+ * @return false if the stack can't pop or true if a top fragment has been popped.
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+ */
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+ public boolean pop() {
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+ if (manager.getBackStackEntryCount() == 0)
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+ return false;
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+ Fragment top = peek();
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+ manager.popBackStackImmediate();
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+ if (onFragmentRemovedListener != null)
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+ onFragmentRemovedListener.onFragmentRemoved(top);
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+ return true;
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+ }
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+
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+ /**
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+ * Replaces stack contents with just one fragment.
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+ */
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+ public void replace(Fragment fragment) {
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+ List<Fragment> fragments = getFragments();
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+
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+ manager.popBackStackImmediate(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
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+ manager.beginTransaction()
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+ .replace(containerId, fragment, indexToTag(0))
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+ .commit();
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+ manager.executePendingTransactions();
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+
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+ if (onFragmentRemovedListener != null) {
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+ for (Fragment fragment1 : fragments)
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+ onFragmentRemovedListener.onFragmentRemoved(fragment1);
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+ }
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+ }
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+
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+ /**
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+ * Returns the topmost fragment in the stack.
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+ */
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+ public Fragment peek() {
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+ return manager.findFragmentById(containerId);
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+ }
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+
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+ /**
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+ * Returns a back fragment if the fragment is of given class.
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+ * If such fragment does not exist and activity implements the given class then the activity will be returned.
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+ *
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+ * @param fragment a fragment to search from.
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+ * @param callbackType a class of type for callback to search.
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+ * @param <T> a type of callback.
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+ * @return a back fragment or activity.
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+ */
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+ @SuppressWarnings("unchecked")
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+ public <T> T findCallback(Fragment fragment, Class<T> callbackType) {
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+
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+ Fragment back = getBackFragment(fragment);
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+
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+ if (back != null && callbackType.isAssignableFrom(back.getClass()))
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+ return (T)back;
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+
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+ if (callbackType.isAssignableFrom(activity.getClass()))
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+ return (T)activity;
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+
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+ return null;
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+ }
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+
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+ private Fragment getBackFragment(Fragment fragment) {
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+ List<Fragment> fragments = getFragments();
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+ for (int f = fragments.size() - 1; f >= 0; f--) {
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+ if (fragments.get(f) == fragment && f > 0)
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+ return fragments.get(f - 1);
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+ }
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+ return null;
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+ }
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+
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+ private List<Fragment> getFragments() {
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+ List<Fragment> fragments = new ArrayList<>(manager.getBackStackEntryCount() + 1);
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+ for (int i = 0; i < manager.getBackStackEntryCount() + 1; i++) {
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+ Fragment fragment = manager.findFragmentByTag(indexToTag(i));
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+ if (fragment != null)
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+ fragments.add(fragment);
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+ }
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+ return fragments;
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+ }
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+
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+ private String indexToTag(int index) {
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+ return Integer.toString(index);
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+ }
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+}
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inorichi