XamarinAndroid组件教程RecylerView适配器设置动画示例

【示例1-3】下面将在RecylerView的子元素进行滚动时，使用适配器动画。具体的操作步骤如下：

（1）创建一个名为RecylerViewAnimatorsAdapter的项目。

（2）将RecyclerViewAnimators.dll、Square.OkHttp.dll、Square.OkIO.dll、Square.Picasso.dll、Xamarin.Android.Arch.Core.Common.dll、Xamarin.Android.Arch.Lifecycle.Common.dll、Xamarin.Android.Arch.Lifecycle.Runtime.dll、Xamarin.Android.Support.Animated.Vector.Drawable.dll、Xamarin.Android.Support.Annotations.dll、Xamarin.Android.Support.Compat.dll、Xamarin.Android.Support.Core.UI.dll、Xamarin.Android.Support.Core.Utils.dll、Xamarin.Android.Support.Fragment.dll、Xamarin.Android.Support.Media.Compat.dll、Xamarin.Android.Support.v4.dll、Xamarin.Android.Support.v7.AppCompat.dll、Xamarin.Android.Support.v7.RecyclerView.dll和Xamarin.Android.Support.Vector.Drawable.dll库添加到RecylerViewAnimatorsAdapter项目的引用中。

（3）添加图片chip.jpg到RecylerViewAnimatorsAdapter项目的Resources下方的drawable文件夹中。

（4）创建一个xml文件，命名为layout_list_item。

（5）打开layout_list_item.cs文件，构建RecylerView的子元素。代码与RecylerViewAnimatorsItemAnimator项目一样。只不过需要将TextView的颜色设置为黑色。

（6）创建一个适配器文件，命名为DataAdapter。

（7）打开DataAdapter.cs文件，添加以下代码：

using System;using System.Collections.Generic;using System.Linq;using System.Text;using Android.App;using Android.Content;using Android.OS;using Android.Runtime;using Android.Views;using Android.Widget;using Square.Picasso;using Android.Support.V7.Widget;namespace RecylerViewAnimatorsAdapter{    class DataAdapter : RecyclerView.Adapter    {        Context context;        List
     
       dataset;        public DataAdapter(Context context, List
      
        dataset)        {            this.context = context;            this.dataset = dataset;        }        //子元素的个数        public override int ItemCount        {            get            {                return dataset.Count;            }        }        //返回一个自定义的ViewHolder        public override RecyclerView.ViewHolder OnCreateViewHolder(ViewGroup parent, int viewType)        {            var v = LayoutInflater.From(context).Inflate(Resource.Layout.layout_list_item, parent, false);            return new ViewHolder(v);        }        //填充onCreateViewHolder()方法返回的ViewHolder中的控件        public override void OnBindViewHolder(RecyclerView.ViewHolder holder, int position)        {            var h = (ViewHolder)holder;            Picasso.With(context).Load(Resource.Drawable.image).Into(h.Image);            h.Text.Text = dataset[position];        }        private class ViewHolder : RecyclerView.ViewHolder        {            public ImageView Image { get; private set; }            public TextView Text { get; private set; }            public ViewHolder(View itemView)                : base(itemView)            {                Image = itemView.FindViewById
       
        (Resource.Id.image);                Text = itemView.FindViewById
        
         (Resource.Id.text);            }        }    }}
        
       
      
     

　　

（8）打开Main.axml文件，构建RecyclerView。代码如下：

　　

（9）打开MainActivity.cs文件，在RecylerView滚动时使用适配器动画。代码如下：

using Android.App;using Android.Widget;using Android.OS;using Android.Support.V7.Widget;using System.Linq;using RecyclerViewAnimators.Adapters;using Android.Views.Animations;namespace RecylerViewAnimatorsAdapter{    [Activity(Label = "RecylerViewAnimatorsAdapter", MainLauncher = true, Icon = "@mipmap/icon")]    public class MainActivity : Activity    {        static readonly string[] data = {            "Apple", "Ball", "Camera", "Day", "Egg", "Foo", "Google", "Hello", "Iron", "Japan", "Coke",            "Dog", "Cat", "Yahoo", "Sony", "Canon", "Fujitsu", "USA", "Nexus", "LINE", "Haskell", "C++",            "Java", "Go", "Swift", "Objective-c", "Ruby", "PHP", "Bash", "ksh", "C", "Groovy", "Kotlin",            "Chip", "Japan", "U.S.A", "San Francisco", "Paris", "Tokyo", "Silicon Valley", "London",            "Spain", "China", "Taiwan", "Asia", "New York", "France", "Kyoto", "Android", "Google", "C#",            "iPhone", "iPad", "iPod", "Wasabeef", "Xamarin", "South Africa", "Cape Town", "Microsoft"        };        protected override void OnCreate(Bundle savedInstanceState)        {            base.OnCreate(savedInstanceState);            SetContentView(Resource.Layout.Main);            var recyclerView = FindViewById
     
      (Resource.Id.list);            recyclerView.SetLayoutManager(new LinearLayoutManager(this));            var adapter = new DataAdapter(this, data.ToList());            var alphaAdapter = new AlphaInAnimationAdapter(adapter);             //创建适配器动画            var scaleAdapter = new ScaleInAnimationAdapter(alphaAdapter);  //创建复合适配器动画            scaleAdapter.SetFirstOnly(false);                                                                           //不是显示一次动画效果            scaleAdapter.SetInterpolator(new OvershootInterpolator());                   //设置插值器            recyclerView.SetAdapter(scaleAdapter);                                                //设置适配器        }    }}
     

　　

运行程序后，初始状态如图1.3所示。当滚动子元素后，会看到动画效果。