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      1 /*
      2  * Copyright 2012 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *     http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.example.android.animationsdemo;
     18 
     19 import android.app.Fragment;
     20 import android.app.FragmentManager;
     21 import android.content.Intent;
     22 import android.os.Bundle;
     23 import android.support.v13.app.FragmentStatePagerAdapter;
     24 import android.support.v4.app.FragmentActivity;
     25 import android.support.v4.app.NavUtils;
     26 import android.support.v4.view.PagerAdapter;
     27 import android.support.v4.view.ViewPager;
     28 import android.view.Menu;
     29 import android.view.MenuItem;
     30 
     31 /**
     32  * Demonstrates a "screen-slide" animation using a {@link ViewPager}. Because {@link ViewPager}
     33  * automatically plays such an animation when calling {@link ViewPager#setCurrentItem(int)}, there
     34  * isn't any animation-specific code in this sample.
     35  *
     36  * <p>This sample shows a "next" button that advances the user to the next step in a wizard,
     37  * animating the current screen out (to the left) and the next screen in (from the right). The
     38  * reverse animation is played when the user presses the "previous" button.</p>
     39  *
     40  * @see ScreenSlidePageFragment
     41  */
     42 public class ScreenSlideActivity extends FragmentActivity {
     43     /**
     44      * The number of pages (wizard steps) to show in this demo.
     45      */
     46     private static final int NUM_PAGES = 5;
     47 
     48     /**
     49      * The pager widget, which handles animation and allows swiping horizontally to access previous
     50      * and next wizard steps.
     51      */
     52     private ViewPager mPager;
     53 
     54     /**
     55      * The pager adapter, which provides the pages to the view pager widget.
     56      */
     57     private PagerAdapter mPagerAdapter;
     58 
     59     @Override
     60     protected void onCreate(Bundle savedInstanceState) {
     61         super.onCreate(savedInstanceState);
     62         setContentView(R.layout.activity_screen_slide);
     63 
     64         // Instantiate a ViewPager and a PagerAdapter.
     65         mPager = (ViewPager) findViewById(R.id.pager);
     66         mPagerAdapter = new ScreenSlidePagerAdapter(getFragmentManager());
     67         mPager.setAdapter(mPagerAdapter);
     68         mPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
     69             @Override
     70             public void onPageSelected(int position) {
     71                 // When changing pages, reset the action bar actions since they are dependent
     72                 // on which page is currently active. An alternative approach is to have each
     73                 // fragment expose actions itself (rather than the activity exposing actions),
     74                 // but for simplicity, the activity provides the actions in this sample.
     75                 invalidateOptionsMenu();
     76             }
     77         });
     78     }
     79 
     80     @Override
     81     public boolean onCreateOptionsMenu(Menu menu) {
     82         super.onCreateOptionsMenu(menu);
     83         getMenuInflater().inflate(R.menu.activity_screen_slide, menu);
     84 
     85         menu.findItem(R.id.action_previous).setEnabled(mPager.getCurrentItem() > 0);
     86 
     87         // Add either a "next" or "finish" button to the action bar, depending on which page
     88         // is currently selected.
     89         MenuItem item = menu.add(Menu.NONE, R.id.action_next, Menu.NONE,
     90                 (mPager.getCurrentItem() == mPagerAdapter.getCount() - 1)
     91                         ? R.string.action_finish
     92                         : R.string.action_next);
     93         item.setShowAsAction(MenuItem.SHOW_AS_ACTION_IF_ROOM | MenuItem.SHOW_AS_ACTION_WITH_TEXT);
     94         return true;
     95     }
     96 
     97     @Override
     98     public boolean onOptionsItemSelected(MenuItem item) {
     99         switch (item.getItemId()) {
    100             case android.R.id.home:
    101                 // Navigate "up" the demo structure to the launchpad activity.
    102                 // See http://developer.android.com/design/patterns/navigation.html for more.
    103                 NavUtils.navigateUpTo(this, new Intent(this, MainActivity.class));
    104                 return true;
    105 
    106             case R.id.action_previous:
    107                 // Go to the previous step in the wizard. If there is no previous step,
    108                 // setCurrentItem will do nothing.
    109                 mPager.setCurrentItem(mPager.getCurrentItem() - 1);
    110                 return true;
    111 
    112             case R.id.action_next:
    113                 // Advance to the next step in the wizard. If there is no next step, setCurrentItem
    114                 // will do nothing.
    115                 mPager.setCurrentItem(mPager.getCurrentItem() + 1);
    116                 return true;
    117         }
    118 
    119         return super.onOptionsItemSelected(item);
    120     }
    121 
    122     /**
    123      * A simple pager adapter that represents 5 {@link ScreenSlidePageFragment} objects, in
    124      * sequence.
    125      */
    126     private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {
    127         public ScreenSlidePagerAdapter(FragmentManager fm) {
    128             super(fm);
    129         }
    130 
    131         @Override
    132         public Fragment getItem(int position) {
    133             return ScreenSlidePageFragment.create(position);
    134         }
    135 
    136         @Override
    137         public int getCount() {
    138             return NUM_PAGES;
    139         }
    140     }
    141 }
    142