打造通用下拉刷新上拉加载更多组件
android开发中最常用的就是列表组件，如ListView，recycleView，用到它们感觉就会涉及到数据更新，分页加载。
最开始的时候，刷新组件我是在技术群里头找了一个被人绑定好的库，是绑定的github上一个星星很多的java原生组件。但是demo很简单，对于当时小白的我懵逼了，不晓得咋个用，而且一直觉得banding的库总感觉有问题，就想着直接找一个java的库翻译成C#版本的。功夫不负苦心人，在csdn上找到了一篇http://blog.csdn.net/zhongkejingwang/article/details/38868463
写的很详细，翻译起来也省了不少力，也很感谢原作者。
突然想起一句话，叫做我们不生产代码，只是代码的搬运工！
这里贴上我翻译好的其中几个很重要的组件的代码:
1.PullToRefreshLayout
using System;using System.Threading.Tasks;using Android.Content;using Android.OS;using Android.Util;using Android.Views;using Android.Views.Animations;using Android.Widget;using CNBlog.Droid.Utils;namespace CNBlog.Droid.PullableView
{ public class PullToRefreshLayout : RelativeLayout
{ // 初始状态
private const int initStatus = 0; // 释放刷新
private const int releaseToRefresh = 1; // 正在刷新
private const int refreshing = 2; // 释放加载
private const int releaseToLoad = 3; // 正在加载
private const int loading = 4; // 操作完毕
private const int complete = 5; // 当前状态
private int currentStatus = 0; // 刷新回调接口
private OnRefreshListener mListener; // 刷新成功
private const int succeed = 0; // 刷新失败
private const int failed = 1; // 按下Y坐标，上一个事件点Y坐标
private float downY, lastY; // 下拉的距离。注意：pullDownY和pullUpY不可能同时不为0
private float pullDownY = 0; // 上拉的距离
private float pullUpY = 0; // 释放刷新的距离
private float refreshDist = 200; // 释放加载的距离
private float loadmoreDist = 200; private UIScheduling uScheduling; // 回滚速度
private float moveSpeed = 8; // 第一次执行布局
private bool isLayout = false; // 在刷新过程中滑动操作
private bool isTouch = false; // 手指滑动距离与下拉头的滑动距离比，中间会随正切函数变化
private float radio = 2; // 下拉箭头的转180°动画
private RotateAnimation rotateAnimation; // 均匀旋转动画
private RotateAnimation refreshingAnimation; // 下拉头
private View refreshView; // 下拉的箭头
public View pullView; // 正在刷新的图标
private View refreshingView; // 刷新结果图标
private View refreshStateImageView; // 刷新结果：成功或失败
private TextView refreshStateTextView; // 上拉头
private View loadmoreView; // 上拉的箭头
public View pullUpView; // 正在加载的图标
private View loadingView; // 加载结果图标
private View loadStateImageView; // 加载结果：成功或失败
private TextView loadStateTextView; //请求加载错误View
private View errorView; // 实现了Pullable接口的View
private View pullableView; // 过滤多点触碰
private int mEvents; // 这两个变量用来控制pull的方向，如果不加控制，当情况满足可上拉又可下拉时没法下拉
private bool canPullDown = true; private bool canPullUp = true; private Context mContext; private Handler updateUIHandler; public void setOnRefreshListener(OnRefreshListener listener)
{
mListener = listener;
} public PullToRefreshLayout(Context context)
: base(context)
{
initView(context);
} public PullToRefreshLayout(Context context, IAttributeSet attrs)
: base(context, attrs)
{
initView(context);
} public PullToRefreshLayout(Context context, IAttributeSet attrs, int defStyle)
: base(context, attrs, defStyle)
{
initView(context);
} private void initView(Context context)
{
mContext = context;
updateUIHandler = new Handler((Message msg) =>
{ // 回弹速度随下拉距离moveDeltaY增大而增大
moveSpeed = (float)(8 + 5 * Math.Tan(Math.PI / 2 / MeasuredHeight * (pullDownY + Math.Abs(pullUpY)))); if (!isTouch)
{ // 正在刷新，且没有往上推的话则悬停，显示"正在刷新..."
if (currentStatus == refreshing && pullDownY <= refreshDist)
{
pullDownY = refreshDist;
uScheduling.Cancel();
} else if (currentStatus == loading && -pullUpY <= loadmoreDist)
{
pullUpY = -loadmoreDist;
uScheduling.Cancel();
}
} if (pullDownY > 0)
pullDownY -= moveSpeed; else if (pullUpY < 0)
pullUpY += moveSpeed; if (pullDownY < 0)
{ // 已完成回弹
pullDownY = 0;
pullView.ClearAnimation(); // 隐藏下拉头时有可能还在刷新，只有当前状态不是正在刷新时才改变状态
if (currentStatus != refreshing && currentStatus != loading)
changeStatus(initStatus);
uScheduling.Cancel();
RequestLayout();
} if (pullUpY > 0)
{ // 已完成回弹
pullUpY = 0;
pullUpView.ClearAnimation(); // 隐藏上拉头时有可能还在刷新，只有当前状态不是正在刷新时才改变状态
if (currentStatus != refreshing && currentStatus != loading)
changeStatus(initStatus);
uScheduling.Cancel();
RequestLayout();
} // 刷新布局,会自动调用onLayout RequestLayout(); // 没有拖拉或者回弹完成
if (pullDownY + Math.Abs(pullUpY) == 0)
{
uScheduling.Cancel();
}
});
uScheduling = new UIScheduling(updateUIHandler);
rotateAnimation = (RotateAnimation)AnimationUtils.LoadAnimation(
context, Resource.Animator.reverse_anim);
refreshingAnimation = (RotateAnimation)AnimationUtils.LoadAnimation(
context, Resource.Animator.rotating); // 添加匀速转动动画
LinearInterpolator lir = new LinearInterpolator();
rotateAnimation.Interpolator = lir;
refreshingAnimation.Interpolator = lir;
} private void initView()
{ // 初始化下拉布局
pullView = refreshView.FindViewById<View>(Resource.Id.pull_icon);
refreshStateTextView = refreshView.FindViewById<TextView>(Resource.Id.state_tv);
refreshingView = refreshView.FindViewById<View>(Resource.Id.refreshing_icon);
refreshStateImageView = refreshView.FindViewById<View>(Resource.Id.state_iv); // 初始化上拉布局
pullUpView = loadmoreView.FindViewById<View>(Resource.Id.pullup_icon);
loadStateTextView = loadmoreView.FindViewById<TextView>(Resource.Id.loadstate_tv);
loadingView = loadmoreView.FindViewById<View>(Resource.Id.loading_icon);
loadStateImageView = loadmoreView.FindViewById<View>(Resource.Id.loadstate_iv);
} /// <summary>
/// 完成刷新操作，显示刷新结果。注意：刷新完成后一定要调用这个方法 /// </summary>
/// <param name="refreshResult">succeed代表成功, failed代表失败</param>
public void refreshFinish(int refreshResult)
{
refreshingView.ClearAnimation();
refreshingView.Visibility = ViewStates.Gone; switch (refreshResult)
{ case 0: // 刷新成功
refreshStateImageView.Visibility = ViewStates.Visible;
refreshStateTextView.Text = "刷新成功";
refreshStateImageView.SetBackgroundResource(Resource.Mipmap.refresh_succeed); break; case 1: default: // 刷新失败
refreshStateImageView.Visibility = ViewStates.Visible;
refreshStateTextView.Text = "刷新失败";
refreshStateImageView.SetBackgroundResource(Resource.Mipmap.refresh_failed); break;
} if (pullDownY > 0)
{ // 刷新结果停留1秒
new Handler((Message msg) =>
{
changeStatus(complete);
hide();
}).SendEmptyMessageDelayed(0, 1000);
} else
{
changeStatus(complete);
hide();
}
} /// <summary>
/// 加载完毕，显示加载结果。注意：刷新完成后一定要调用这个方法 /// </summary>
/// <param name="refreshResult">succeed代表成功, failed代表失败</param>
public void loadmoreFinish(int refreshResult)
{
loadingView.ClearAnimation();
loadingView.Visibility = ViewStates.Gone; switch (refreshResult)
{ case 0: // 加载成功
loadStateImageView.Visibility = ViewStates.Visible;
loadStateTextView.Text = "加载成功";
loadStateImageView.SetBackgroundResource(Resource.Mipmap.load_succeed); break; case 1: default: // 加载失败
loadStateImageView.Visibility = ViewStates.Visible;
loadStateTextView.Text = "加载失败";
loadStateImageView.SetBackgroundResource(Resource.Mipmap.load_failed);
pullableView.Visibility = ViewStates.Gone; break;
} if (pullUpY < 0)
{ // 刷新结果停留1秒
new Handler((Message msg) =>
{
changeStatus(complete);
hide();
}).SendEmptyMessageDelayed(0, 1000);
} else
{
changeStatus(complete);
hide();
}
} /// <summary>
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