supportv4/widget/DrawerLayoutActivity.java

/*
 * Copyright (C) 2013 The Android Open Source Project
 *
 * 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.example.android.supportv4.widget;

import android.app.ActionBar;
import android.app.Activity;
import android.content.res.Configuration;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.app.ActionBarDrawerToggle;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.view.Gravity;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;
import com.example.android.supportv4.R;
import com.example.android.supportv4.Shakespeare;

/**
 * This example illustrates a common usage of the DrawerLayout widget
 * in the Android support library.
 *
 * <p>A DrawerLayout should be positioned at the top of your view hierarchy, placing it
 * below the action bar but above your content views. The primary content should match_parent
 * in both dimensions. Each drawer should define a reasonable width and match_parent for height.
 * Drawer views should be positioned after the content view in your layout to preserve proper
 * ordering.</p>
 *
 * <p>When a navigation (left) drawer is present, the host activity should detect presses of
 * the action bar's Up affordance as a signal to open and close the navigation drawer.
 * Items within the drawer should fall into one of two categories.</p>
 *
 * <ul>
 *     <li><strong>View switches</strong>. A view switch follows the same basic policies as
 *     list or tab navigation in that a view switch does not create navigation history.
 *     This pattern should only be used at the root activity of a task, leaving some form
 *     of Up navigation active for activities further down the navigation hierarchy.</li>
 *     <li><strong>Selective Up</strong>. The drawer allows the user to choose an alternate
 *     parent for Up navigation. This allows a user to jump across an app's navigation
 *     hierarchy at will. The application should treat this as it treats Up navigation from
 *     a different task, replacing the current task stack using TaskStackBuilder or similar.
 *     This is the only form of navigation drawer that should be used outside of the root
 *     activity of a task.</li>
 * </ul>
 *
 * <p>Right side drawers should be used for actions, not navigation. This follows the pattern
 * established by the Action Bar that navigation should be to the left and actions to the right.
 * An action should be an operation performed on the current contents of the window,
 * for example enabling or disabling a data overlay on top of the current content.</p>
 */
public class DrawerLayoutActivity extends Activity {
    private DrawerLayout mDrawerLayout;
    private ListView mDrawer;
    private TextView mContent;

    private ActionBarHelper mActionBar;

    private ActionBarDrawerToggle mDrawerToggle;

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

        setContentView(R.layout.drawer_layout);

        mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
        mDrawer = (ListView) findViewById(R.id.start_drawer);
        mContent = (TextView) findViewById(R.id.content_text);

        mDrawerLayout.setDrawerListener(new DemoDrawerListener());
        mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START);

        // The drawer title must be set in order to announce state changes when
        // accessibility is turned on. This is typically a simple description,
        // e.g. "Navigation".
        mDrawerLayout.setDrawerTitle(GravityCompat.START, getString(R.string.drawer_title));

        mDrawer.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1,
                Shakespeare.TITLES));
        mDrawer.setOnItemClickListener(new DrawerItemClickListener());

        mActionBar = createActionBarHelper();
        mActionBar.init();

        // ActionBarDrawerToggle provides convenient helpers for tying together the
        // prescribed interactions between a top-level sliding drawer and the action bar.
        mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout,
                R.drawable.ic_drawer, R.string.drawer_open, R.string.drawer_close);
    }

    @Override
    protected void onPostCreate(Bundle savedInstanceState) {
        super.onPostCreate(savedInstanceState);

        // Sync the toggle state after onRestoreInstanceState has occurred.
        mDrawerToggle.syncState();
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        /*
         * The action bar home/up action should open or close the drawer.
         * mDrawerToggle will take care of this.
         */
        if (mDrawerToggle.onOptionsItemSelected(item)) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);
        mDrawerToggle.onConfigurationChanged(newConfig);
    }

    /**
     * This list item click listener implements very simple view switching by changing
     * the primary content text. The drawer is closed when a selection is made.
     */
    private class DrawerItemClickListener implements ListView.OnItemClickListener {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            mContent.setText(Shakespeare.DIALOGUE[position]);
            mActionBar.setTitle(Shakespeare.TITLES[position]);
            mDrawerLayout.closeDrawer(mDrawer);
        }
    }

    /**
     * A drawer listener can be used to respond to drawer events such as becoming
     * fully opened or closed. You should always prefer to perform expensive operations
     * such as drastic relayout when no animation is currently in progress, either before
     * or after the drawer animates.
     *
     * When using ActionBarDrawerToggle, all DrawerLayout listener methods should be forwarded
     * if the ActionBarDrawerToggle is not used as the DrawerLayout listener directly.
     */
    private class DemoDrawerListener implements DrawerLayout.DrawerListener {
        @Override
        public void onDrawerOpened(View drawerView) {
            mDrawerToggle.onDrawerOpened(drawerView);
            mActionBar.onDrawerOpened();
        }

        @Override
        public void onDrawerClosed(View drawerView) {
            mDrawerToggle.onDrawerClosed(drawerView);
            mActionBar.onDrawerClosed();
        }

        @Override
        public void onDrawerSlide(View drawerView, float slideOffset) {
            mDrawerToggle.onDrawerSlide(drawerView, slideOffset);
        }

        @Override
        public void onDrawerStateChanged(int newState) {
            mDrawerToggle.onDrawerStateChanged(newState);
        }
    }

    /**
     * Create a compatible helper that will manipulate the action bar if available.
     */
    private ActionBarHelper createActionBarHelper() {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
            return new ActionBarHelperICS();
        } else {
            return new ActionBarHelper();
        }
    }

    /**
     * Stub action bar helper; this does nothing.
     */
    private class ActionBarHelper {
        public void init() {}
        public void onDrawerClosed() {}
        public void onDrawerOpened() {}
        public void setTitle(CharSequence title) {}
    }

    /**
     * Action bar helper for use on ICS and newer devices.
     */
    private class ActionBarHelperICS extends ActionBarHelper {
        private final ActionBar mActionBar;
        private CharSequence mDrawerTitle;
        private CharSequence mTitle;

        ActionBarHelperICS() {
            mActionBar = getActionBar();
        }

        @Override
        public void init() {
            mActionBar.setDisplayHomeAsUpEnabled(true);
            mActionBar.setHomeButtonEnabled(true);
            mTitle = mDrawerTitle = getTitle();
        }

        /**
         * When the drawer is closed we restore the action bar state reflecting
         * the specific contents in view.
         */
        @Override
        public void onDrawerClosed() {
            super.onDrawerClosed();
            mActionBar.setTitle(mTitle);
        }

        /**
         * When the drawer is open we set the action bar to a generic title.
         * The action bar should only contain data relevant at the top level of
         * the nav hierarchy represented by the drawer, as the rest of your content
         * will be dimmed down and non-interactive.
         */
        @Override
        public void onDrawerOpened() {
            super.onDrawerOpened();
            mActionBar.setTitle(mDrawerTitle);
        }

        @Override
        public void setTitle(CharSequence title) {
            mTitle = title;
        }
    }
}