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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.Activity;
     20 import android.content.Intent;
     21 import android.os.Bundle;
     22 import android.support.v4.app.NavUtils;
     23 import android.view.LayoutInflater;
     24 import android.view.Menu;
     25 import android.view.MenuItem;
     26 import android.view.View;
     27 import android.view.ViewGroup;
     28 import android.widget.TextView;
     29 
     30 /**
     31  * This sample demonstrates how to use system-provided, automatic layout transitions. Layout
     32  * transitions are animations that occur when views are added to, removed from, or changed within
     33  * a {@link ViewGroup}.
     34  *
     35  * <p>In this sample, the user can add rows to and remove rows from a vertical
     36  * {@link android.widget.LinearLayout}.</p>
     37  */
     38 public class LayoutChangesActivity extends Activity {
     39     /**
     40      * The container view which has layout change animations turned on. In this sample, this view
     41      * is a {@link android.widget.LinearLayout}.
     42      */
     43     private ViewGroup mContainerView;
     44 
     45     @Override
     46     protected void onCreate(Bundle savedInstanceState) {
     47         super.onCreate(savedInstanceState);
     48         setContentView(R.layout.activity_layout_changes);
     49 
     50         mContainerView = (ViewGroup) findViewById(R.id.container);
     51     }
     52 
     53     @Override
     54     public boolean onCreateOptionsMenu(Menu menu) {
     55         super.onCreateOptionsMenu(menu);
     56         getMenuInflater().inflate(R.menu.activity_layout_changes, menu);
     57         return true;
     58     }
     59 
     60     @Override
     61     public boolean onOptionsItemSelected(MenuItem item) {
     62         switch (item.getItemId()) {
     63             case android.R.id.home:
     64                 // Navigate "up" the demo structure to the launchpad activity.
     65                 // See http://developer.android.com/design/patterns/navigation.html for more.
     66                 NavUtils.navigateUpTo(this, new Intent(this, MainActivity.class));
     67                 return true;
     68 
     69             case R.id.action_add_item:
     70                 // Hide the "empty" view since there is now at least one item in the list.
     71                 findViewById(android.R.id.empty).setVisibility(View.GONE);
     72                 addItem();
     73                 return true;
     74         }
     75 
     76         return super.onOptionsItemSelected(item);
     77     }
     78 
     79     private void addItem() {
     80         // Instantiate a new "row" view.
     81         final ViewGroup newView = (ViewGroup) LayoutInflater.from(this).inflate(
     82                 R.layout.list_item_example, mContainerView, false);
     83 
     84         // Set the text in the new row to a random country.
     85         ((TextView) newView.findViewById(android.R.id.text1)).setText(
     86                 COUNTRIES[(int) (Math.random() * COUNTRIES.length)]);
     87 
     88         // Set a click listener for the "X" button in the row that will remove the row.
     89         newView.findViewById(R.id.delete_button).setOnClickListener(new View.OnClickListener() {
     90             @Override
     91             public void onClick(View view) {
     92                 // Remove the row from its parent (the container view).
     93                 // Because mContainerView has android:animateLayoutChanges set to true,
     94                 // this removal is automatically animated.
     95                 mContainerView.removeView(newView);
     96 
     97                 // If there are no rows remaining, show the empty view.
     98                 if (mContainerView.getChildCount() == 0) {
     99                     findViewById(android.R.id.empty).setVisibility(View.VISIBLE);
    100                 }
    101             }
    102         });
    103 
    104         // Because mContainerView has android:animateLayoutChanges set to true,
    105         // adding this view is automatically animated.
    106         mContainerView.addView(newView, 0);
    107     }
    108 
    109     /**
    110      * A static list of country names.
    111      */
    112     private static final String[] COUNTRIES = new String[]{
    113             "Belgium", "France", "Italy", "Germany", "Spain",
    114             "Austria", "Russia", "Poland", "Croatia", "Greece",
    115             "Ukraine",
    116     };
    117 }
    118