Android Open Source - E-merg Navigation Drawer Fragment

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License

The source code is released under:

Apache License

Java Source Code

package com.e_merg.fragments;
/* w  w  w  .jav a2s.  c  om*/
import java.util.ArrayList;
import java.util.List;

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.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ListView;

import com.e_merg.R;
import com.e_merg.adapters.NavigationAdapter;

/**
 * Fragment used for managing interactions for and presentation of a navigation
 * drawer. See the <a href=
 * "https://developer.android.com/design/patterns/navigation-drawer.html#Interaction"
 * > design guidelines</a> for a complete explanation of the behaviors
 * implemented here.
 */
public class NavigationDrawerFragment extends Fragment {

  /**
   * Remember the position of the selected item.
   */
  private static final String STATE_SELECTED_POSITION = "selected_navigation_drawer_position";

  /**
   * Per the design guidelines, you should show the drawer on launch until the
   * user manually expands it. This shared preference tracks this.
   */
  private static final String PREF_USER_LEARNED_DRAWER = "navigation_drawer_learned";

  /**
   * A pointer to the current callbacks instance (the Activity).
   */
  private NavigationDrawerCallbacks mCallbacks;

  /**
   * Helper component that ties the action bar to the navigation drawer.
   */
  private ActionBarDrawerToggle mDrawerToggle;

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

  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);
          }
        });
    
    navigationAdapter = new NavigationAdapter(getActivity());
    List<String> items = new ArrayList<String>();
    items.add(getString(R.string.nav_nearby));
    items.add(getString(R.string.nav_add));
    items.add(getString(R.string.nav_feedback));
    navigationAdapter.setNavigationItems(items);
    
    mDrawerListView.setAdapter(navigationAdapter);
    
    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)
              .commit();
        }

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

    return super.onOptionsItemSelected(item);
  }


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

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

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