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
onCreate(Bundle savedInstanceState)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
onCreateOptionsMenu(Menu menu)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
onOptionsItemSelected(MenuItem item)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 {
ScreenSlidePagerAdapter(FragmentManager fm)127         public ScreenSlidePagerAdapter(FragmentManager fm) {
128             super(fm);
129         }
130 
131         @Override
getItem(int position)132         public Fragment getItem(int position) {
133             return ScreenSlidePageFragment.create(position);
134         }
135 
136         @Override
getCount()137         public int getCount() {
138             return NUM_PAGES;
139         }
140     }
141 }
142