Destroy fragment's presenter when they aren't needed using FragmentStack class from Nucleus' examples
inorichi
9 years ago
parent
11563e6f95
commit
b389db9773
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package eu.kanade.mangafeed.ui.main;
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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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import java.util.ArrayList;
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import java.util.List;
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import eu.kanade.mangafeed.R;
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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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public interface OnBackPressedHandlingFragment {
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boolean onBackPressed();
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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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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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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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* 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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* 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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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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manager.executePendingTransactions();
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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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* 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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* 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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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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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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* 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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* 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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Fragment back = getBackFragment(fragment);
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if (back != null && callbackType.isAssignableFrom(back.getClass()))
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return (T)back;
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if (callbackType.isAssignableFrom(activity.getClass()))
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return (T)activity;
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return null;
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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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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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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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@ -0,0 +1,8 @@
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<?xml version="1.0" encoding="utf-8"?>
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<set xmlns:android="http://schemas.android.com/apk/res/android"
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android:shareInterpolator="false">
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<translate
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android:duration="400"
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android:fromXDelta="-100%"
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android:toXDelta="0%" />
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</set>
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@ -0,0 +1,8 @@
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<?xml version="1.0" encoding="utf-8"?>
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<set xmlns:android="http://schemas.android.com/apk/res/android"
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android:shareInterpolator="false">
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<translate
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android:duration="400"
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android:fromXDelta="100%"
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android:toXDelta="0%" />
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</set>
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@ -0,0 +1,8 @@
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<?xml version="1.0" encoding="utf-8"?>
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<set xmlns:android="http://schemas.android.com/apk/res/android"
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android:shareInterpolator="false">
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<translate
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android:duration="400"
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android:fromXDelta="0%"
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android:toXDelta="-100%" />
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</set>
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@ -0,0 +1,8 @@
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<?xml version="1.0" encoding="utf-8"?>
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<set xmlns:android="http://schemas.android.com/apk/res/android"
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android:shareInterpolator="false">
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<translate
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android:duration="400"
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android:fromXDelta="0%"
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android:toXDelta="100%" />
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</set>
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