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NavigationDrawerFragment.java

/*
 * Copyright (C) 2015 Google, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.google.android.gms.example.apidemo;

import android.app.Activity;
import android.content.SharedPreferences;
import android.content.res.Configuration;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.support.v4.app.ActionBarDrawerToggle;
import android.support.v4.app.Fragment;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBar;
import android.support.v7.app.AppCompatActivity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;

/**
 * The {@link NavigationDrawerFragment} contains a horizontal {@link android.widget.ListView}
 * displaying the names of available demo fragments.  It's placed in the drawer of the
 * app's {@link com.google.android.gms.example.apidemo.MainActivity}.
 */
public class NavigationDrawerFragment extends Fragment {

private static final String STATE_SELECTED_POSITION = "selected_navigation_drawer_position";
    private static final String PREF_USER_LEARNED_DRAWER = "navigation_drawer_learned";

private NavigationDrawerCallbacks mCallbacks;
    private ActionBarDrawerToggle mDrawerToggle;

private DrawerLayout mDrawerLayout;
    private ListView mDrawerListView;
    private View mFragmentContainerView;

private int mCurrentSelectedPosition = 0;
    private boolean mFromSavedInstanceState;
    private boolean mUserLearnedDrawer;

public NavigationDrawerFragment() {
    }

@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

// Read in the flag indicating whether or not the user has demonstrated awareness of the
        // drawer. See PREF_USER_LEARNED_DRAWER for details.
        SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(getActivity());
        mUserLearnedDrawer = sp.getBoolean(PREF_USER_LEARNED_DRAWER, false);

if (savedInstanceState != null) {
            mCurrentSelectedPosition = savedInstanceState.getInt(STATE_SELECTED_POSITION);
            mFromSavedInstanceState = true;
        }

// Select either the default item (0) or the last selected item.
        selectItem(mCurrentSelectedPosition);
    }

@Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        // Indicate that this fragment would like to influence the set of actions in the action bar.
        setHasOptionsMenu(true);
    }

@Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        mDrawerListView = (ListView) inflater.inflate(
                R.layout.fragment_navigation_drawer, container, false);
        mDrawerListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                selectItem(position);
            }
        });
        mDrawerListView.setAdapter(new ArrayAdapter<>(
                getActionBar().getThemedContext(),
                android.R.layout.simple_list_item_1,
                android.R.id.text1,
                getResources().getStringArray(R.array.fragment_names)));
        mDrawerListView.setItemChecked(mCurrentSelectedPosition, true);
        return mDrawerListView;
    }

public boolean isDrawerOpen() {
        return mDrawerLayout != null && mDrawerLayout.isDrawerOpen(mFragmentContainerView);
    }

/**
     * Users of this fragment must call this method to set up the navigation drawer interactions.
     *
     * @param fragmentId   The android:id of this fragment in its activity's layout.
     * @param drawerLayout The DrawerLayout containing this fragment's UI.
     */
    public void setUp(int fragmentId, DrawerLayout drawerLayout) {
        mFragmentContainerView = getActivity().findViewById(fragmentId);
        mDrawerLayout = drawerLayout;

// set a custom shadow that overlays the main content when the drawer opens
        mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START);
        // set up the drawer's list view with items and click listener

ActionBar actionBar = getActionBar();
        actionBar.setDisplayHomeAsUpEnabled(true);
        actionBar.setHomeButtonEnabled(true);

// ActionBarDrawerToggle ties together the the proper interactions
        // between the navigation drawer and the action bar app icon.
        mDrawerToggle = new ActionBarDrawerToggle(
                getActivity(),                    /* host Activity */
                mDrawerLayout,                    /* DrawerLayout object */
                R.drawable.ic_drawer,             /* nav drawer image to replace 'Up' caret */
                R.string.navigation_drawer_open,  /* "open drawer" description for accessibility */
                R.string.navigation_drawer_close  /* "close drawer" description for accessibility */
        ) {
            @Override
            public void onDrawerClosed(View drawerView) {
                super.onDrawerClosed(drawerView);
                if (!isAdded()) {
                    return;
                }

getActivity().supportInvalidateOptionsMenu(); // calls onPrepareOptionsMenu()
            }

@Override
            public void onDrawerOpened(View drawerView) {
                super.onDrawerOpened(drawerView);
                if (!isAdded()) {
                    return;
                }

if (!mUserLearnedDrawer) {
                    // The user manually opened the drawer; store this flag to prevent auto-showing
                    // the navigation drawer automatically in the future.
                    mUserLearnedDrawer = true;
                    SharedPreferences sp = PreferenceManager
                            .getDefaultSharedPreferences(getActivity());
                    sp.edit().putBoolean(PREF_USER_LEARNED_DRAWER, true).apply();
                }

getActivity().supportInvalidateOptionsMenu(); // calls onPrepareOptionsMenu()
            }
        };

// If the user hasn't 'learned' about the drawer, open it to introduce them to the drawer,
        // per the navigation drawer design guidelines.
        if (!mUserLearnedDrawer && !mFromSavedInstanceState) {
            mDrawerLayout.openDrawer(mFragmentContainerView);
        }

// Defer code dependent on restoration of previous instance state.
        mDrawerLayout.post(new Runnable() {
            @Override
            public void run() {
                mDrawerToggle.syncState();
            }
        });

mDrawerLayout.setDrawerListener(mDrawerToggle);
    }

private void selectItem(int position) {
        mCurrentSelectedPosition = position;
        if (mDrawerListView != null) {
            mDrawerListView.setItemChecked(position, true);
        }
        if (mDrawerLayout != null) {
            mDrawerLayout.closeDrawer(mFragmentContainerView);
        }
        if (mCallbacks != null) {
            mCallbacks.onNavigationDrawerItemSelected(position);
        }
    }

@Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        try {
            mCallbacks = (NavigationDrawerCallbacks) activity;
        } catch (ClassCastException e) {
            throw new ClassCastException("Activity must implement NavigationDrawerCallbacks.");
        }
    }

@Override
    public void onDetach() {
        super.onDetach();
        mCallbacks = null;
    }

@Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putInt(STATE_SELECTED_POSITION, mCurrentSelectedPosition);
    }

@Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);
        // Forward the new configuration the drawer toggle component.
        mDrawerToggle.onConfigurationChanged(newConfig);
    }

@Override
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
        // If the drawer is open, show the global app actions in the action bar. See also
        // showGlobalContextActionBar, which controls the top-left area of the action bar.
        if (mDrawerLayout != null && isDrawerOpen()) {
            inflater.inflate(R.menu.global, menu);
            showGlobalContextActionBar();
        }
        super.onCreateOptionsMenu(menu, inflater);
    }

@Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if (mDrawerToggle.onOptionsItemSelected(item)) {
            return true;
        }

return super.onOptionsItemSelected(item);
    }

/**
     * Per the navigation drawer design guidelines, updates the action bar to show the global app
     * 'context', rather than just what's in the current screen.
     */
    private void showGlobalContextActionBar() {
        ActionBar actionBar = getActionBar();
        actionBar.setDisplayShowTitleEnabled(true);
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
        actionBar.setTitle(R.string.app_name);
    }

private ActionBar getActionBar() {
        return ((AppCompatActivity) getActivity()).getSupportActionBar();
    }

/**
     * Callbacks interface that all activities using this fragment must implement.
     */
    public interface NavigationDrawerCallbacks {
        /**
         * Called when an item in the navigation drawer is selected.
         */
        void onNavigationDrawerItemSelected(int position);
    }
}