Android自定义下拉刷新控件RefreshableView

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package com.pull2refresh;

import android.animation.ObjectAnimator;
import android.animation.ValueAnimator;
import android.annotation.TargetApi;
import android.content.Context;
import android.os.Build;
import android.util.AttributeSet;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.view.animation.RotateAnimation;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.ProgressBar;
import android.widget.TextView;

import shike.xianrou.com.pull2refresh.R;

/**
 * Created by cjh on 16-9-6.
 */
public class RefreshableView extends LinearLayout implements View.OnTouchListener {

 private static final String TAG = "RefreshableView";

 private static final int REFRESHING = 0;//正在刷新
 private static final int ORIGINAL = REFRESHING + 1;//初始状态
 private static final int RELEASE_TO_REFRESHING = ORIGINAL + 1;//释放即将刷新的状态

 private int current_status = ORIGINAL;//当前最新状态

 private LinearLayout headView;//刷新layout
 private TextView textView;//刷新layout中的文字提示
 private ImageView imageView;//刷新layout中的箭头
 private ProgressBar progressBar;//刷新layout中的进度条

 private View view;//手指控制的下拉的View

 private int hideHeight;//刷新layout要隐藏的高度

 private boolean isablePull;//是否可以下拉，例如当 current_status = REFRESHIING 时是不可以下拉拖拽的

 private float yDown;//手指按下的坐标

 private int touchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();//界限值，防止手指误触，过于灵敏

 private boolean firstLayout = true;//第一次调用onLayout的时候置为false

 private int maxMarginTop;//刷新Layout能拉下的最大距离

 private MarginLayoutParams marginLayoutParams;//刷新layout的MarginLayoutParams

 private String pull_to_refresh = "下拉可以刷新";

 private String release_to_refresh = "释放立即刷新";

 private String refreshing = "正在刷新…";


 private int original_margin = 0;//针对下拉的View存在MarginTop这中特殊值的处理

 public interface PullToRefreshListener {

 void onRefresh();
 }

 private PullToRefreshListener pullToRefreshListener;

 public void addPullToRefreshListener(PullToRefreshListener pullToRefreshListener) {
 this.pullToRefreshListener = pullToRefreshListener;
 }

 public RefreshableView(Context context) {
 super(context);
 init();
 }

 public RefreshableView(Context context, AttributeSet attrs) {
 super(context, attrs);
 init();
 }

 public RefreshableView(Context context, AttributeSet attrs, int defStyleAttr) {
 super(context, attrs, defStyleAttr);
 init();
 }

 @TargetApi(Build.VERSION_CODES.LOLLIPOP)
 public RefreshableView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
 super(context, attrs, defStyleAttr, defStyleRes);
 init();
 }

 private void init() {
 headView = (LinearLayout) LayoutInflater.from(getContext()).inflate(R.layout.refresh_layout, null, true);
 imageView = (ImageView) headView.findViewById(R.id.imageView_down);
 progressBar = (ProgressBar) headView.findViewById(R.id.progressBar);
 textView = (TextView) headView.findViewById(R.id.textView);
 progressBar.setVisibility(View.GONE);
 setOrientation(VERTICAL);
 addView(headView, 0);
 }

 @Override
 protected void onLayout(boolean changed, int l, int t, int r, int b) {
 super.onLayout(changed, l, t, r, b);
 Log.d(TAG, "onlayout");
 if (changed && firstLayout) {
  //将View的Touch时间的处理交给RefreshableView去处理
  view = getChildAt(1);
  view.setOnTouchListener(this);

  //刷新layout的 marginTop 的最大值设为刷新头的高度
  maxMarginTop = headView.getHeight();

  //要将控件完全隐藏起来，那么隐藏的高度就设置为控件的高度
  hideHeight = -headView.getHeight();
  marginLayoutParams = (MarginLayoutParams) headView.getLayoutParams();
  marginLayoutParams.topMargin = hideHeight;
  headView.setLayoutParams(marginLayoutParams);

  //这里必须将firstLayout设置为false,否则在处理Touch是件的过程中，headView在怎么调用setLayoutParams都会被置为初始的隐藏状态
  firstLayout = false;

  //如果子View是一个ViewGroup 那么就需要计算出子View的MarginTop的值，因为如果MarginTop不为0，那么子View的Y轴坐标和父View的坐标是不一样的
  if (view instanceof ViewGroup) {
  int[] childLocatiOns= new int[2];
  int[] viewLocatiOns= new int[2];
  view.getLocationOnScreen(viewLocations);
  ((ViewGroup) view).getChildAt(0).getLocationOnScreen(childLocations);
  original_margin = childLocations[1] - viewLocations[1];
  Log.d(TAG, "onLayout viewLocations[1] " + viewLocations[1]);
  Log.d(TAG, "onLayout locations[1] " + childLocations[1]);
  Log.d(TAG, "onLayout original_margin " + original_margin);
  }
 }
 }

 @Override
 public boolean onTouch(View view, MotionEvent motionEvent) {
 if (pullToRefreshListener != null) {
  isAblePull();
  if (isablePull) {
  switch (motionEvent.getAction()) {
   case MotionEvent.ACTION_DOWN:
   yDown = motionEvent.getRawY();
   break;

   case MotionEvent.ACTION_MOVE:
   float yMove = motionEvent.getRawY();
   float distance = yMove - yDown;

   //如果手势是向上的，并且手势在Y轴的移动距离小于界限值，那么就不处理
   if (distance <0 || Math.abs(distance) = maxMarginTop)
    marginLayoutParams.topMargin = maxMarginTop;


   if (marginLayoutParams.topMargin >= 0) {
    //当刷新头完全显示的时候，改变状态，置为 释放刷新的状态
    if (current_status != RELEASE_TO_REFRESHING) {
    rotate(0, 180);
    textView.setText(release_to_refresh);
    }
    current_status = RELEASE_TO_REFRESHING;
   } else {
    //否则就置为初始状态
    if (current_status != ORIGINAL) {
    rotate(180, 360);
    textView.setText(pull_to_refresh);
    }
    current_status = ORIGINAL;

   }
   headView.setLayoutParams(marginLayoutParams);
   break;

   case MotionEvent.ACTION_CANCEL:
   case MotionEvent.ACTION_UP:
   float yUp = motionEvent.getRawY();
   float dis = yUp - yDown;
   if (dis > 0 && Math.abs(dis) > touchSlop)
    switch (current_status) {
    //释放刷新
    case RELEASE_TO_REFRESHING:
     animateMarginTop(marginLayoutParams.topMargin, 0);
     imageView.clearAnimation();
     imageView.setVisibility(View.GONE);
     progressBar.setVisibility(View.VISIBLE);
     textView.setText(refreshing);
     pullToRefreshListener.onRefresh();
     break;

    //初始化
    case ORIGINAL:
     reset();
     //从当前的MarginTop的值，转变到隐藏所需的 MarginTop
     animateMarginTop(marginLayoutParams.topMargin, hideHeight);
     break;
    }
   else
    return false;

   break;
  }
  return true;
  }
 }
 return false;
 }

 /**
 * 判断是否可以下拉
 *
 * @return
 */
 public boolean isAblePull() {
 //统一判断，其实主要是对于view是普通View的判断
 if (current_status != REFRESHING)
  isablePull = true;
 else
  isablePull = false;

 if (view instanceof ViewGroup) {
  isablePull = false;
  View childView = ((ViewGroup) view).getChildAt(0);
  int[] viewLocatiOns= new int[2];
  int[] childViewLocatiOns= new int[2];
  view.getLocationOnScreen(viewLocations);
  childView.getLocationOnScreen(childViewLocations);

  //这一步中的 original_margin 至关重要，就是用来兼容 子View 有MarginTop属性的值，当childView 的Y轴坐标 和 计算出了 Margin 值后的父View坐标相等时，说明此时处于可下拉的状态
  if (viewLocations[1] + original_margin == childViewLocations[1])
  isablePull = true;
  else
  isablePull = false;
 }

 return isablePull;
 }

 private void rotate(int from, int to) {
 RotateAnimation rotateAnimation = new RotateAnimation(from, to, imageView.getWidth() / 2, imageView.getHeight() / 2);
 rotateAnimation.setDuration(100);
 rotateAnimation.setFillAfter(true);
 imageView.startAnimation(rotateAnimation);
 }

 private void animateMarginTop(int from, int to) {
 ObjectAnimator objectAnimator = ObjectAnimator.ofInt(headView, "cjh", from, to);
 objectAnimator.setDuration(300);
 objectAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
  @Override
  public void onAnimationUpdate(ValueAnimator valueAnimator) {
  int margin = (int) valueAnimator.getAnimatedValue();
  marginLayoutParams.topMargin = margin;
  headView.setLayoutParams(marginLayoutParams);
  }
 });
 objectAnimator.start();
 }

 public void complete() {
 animateMarginTop(0, hideHeight);
 reset();
 }

 private void reset() {
 rotate(180, 360);
 textView.setText(pull_to_refresh);
 imageView.setVisibility(View.VISIBLE);
 progressBar.setVisibility(View.GONE);
 }

}

...
 refreshableView.addPullToRefreshListener(new RefreshableView.PullToRefreshListener() {
  @Override
  public void onRefresh() {
  setData();
  }
 });
...
 private void setData() {
 ObjectAnimator objectAnimator = ObjectAnimator.ofFloat(textView, "text", 1f, 100f);
 objectAnimator.setDuration(3000);
 objectAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
  @Override
  public void onAnimationUpdate(ValueAnimator valueAnimator) {
  textView.setText((Float) valueAnimator.getAnimatedValue());
  }
 });
 objectAnimator.addListener(new Animator.AnimatorListener() {
  @Override
  public void onAnimationStart(Animator animator) {

  }

  @Override
  public void onAnimationEnd(Animator animator) {
  refreshableView.complete();
  }

  @Override
  public void onAnimationCancel(Animator animator) {

  }

  @Override
  public void onAnimationRepeat(Animator animator) {

  }
 });
 objectAnimator.start();
 }