/**
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* @file XListView.java
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* @package me.maxwin.view
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* @create Mar 18, 2012 6:28:41 PM
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* @author Maxwin
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* @description An ListView support (a) Pull down to refresh, (b) Pull up to load more.
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* Implement IWaterDropListViewListener, and see stopRefresh() / stopLoadMore().
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*/
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package medusa.theone.waterdroplistview.view;
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import android.content.Context;
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import android.util.AttributeSet;
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import android.util.Log;
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import android.view.MotionEvent;
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import android.view.View;
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import android.view.animation.DecelerateInterpolator;
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import android.widget.AbsListView;
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import android.widget.AbsListView.OnScrollListener;
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import android.widget.ListAdapter;
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import android.widget.ListView;
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import android.widget.Scroller;
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public class WaterDropListView extends ListView implements OnScrollListener,WaterDropListViewHeader.IStateChangedListener {
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private float mLastY = -1; // save event y
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private Scroller mScroller; // used for scroll back
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private OnScrollListener mScrollListener; // user's scroll listener
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// the interface to trigger refresh and load more.
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private IWaterDropListViewListener mListViewListener;
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// -- header view
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private WaterDropListViewHeader mHeaderView;
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// header view content, use it to calculate the Header's height. And hide it
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// when disable pull refresh.
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// private RelativeLayout mHeaderViewContent;
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private boolean mEnablePullRefresh = true;
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// private boolean mPullRefreshing = false; // is refreashing.
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// -- footer view
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private WaterDropListViewFooter mFooterView;
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private boolean mEnablePullLoad;
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private boolean mPullLoading;
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private boolean mIsFooterReady = false;
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// total list items, used to detect is at the bottom of listview.
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private int mTotalItemCount;
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// for mScroller, scroll back from header or footer.
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private ScrollBack mScrollBack;
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private boolean isTouchingScreen = false;//手指是否触摸屏幕
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// private int mStretchHeight; // view开始变形的高度
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// private int mReadyHeight; // view由stretch变成ready的高度
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private final static int SCROLL_DURATION = 400; // scroll back duration
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private final static int PULL_LOAD_MORE_DELTA = 50; // when pull up >= 50px
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// at bottom, trigger
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// load more.
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private final static float OFFSET_RADIO = 1.8f; // support iOS like pull
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private enum ScrollBack{
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header,
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footer
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} // feature.
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/**
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* @param context
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*/
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public WaterDropListView(Context context) {
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super(context);
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initWithContext(context);
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}
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public WaterDropListView(Context context, AttributeSet attrs) {
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super(context, attrs);
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initWithContext(context);
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}
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public WaterDropListView(Context context, AttributeSet attrs, int defStyle) {
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super(context, attrs, defStyle);
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initWithContext(context);
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}
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private void initWithContext(Context context) {
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mScroller = new Scroller(context, new DecelerateInterpolator());
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// XListView need the scroll event, and it will dispatch the event to
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// user's listener (as a proxy).
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super.setOnScrollListener(this);
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// init header view
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mHeaderView = new WaterDropListViewHeader(context);
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mHeaderView.setStateChangedListener(this);
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addHeaderView(mHeaderView);
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// init footer view
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mFooterView = new WaterDropListViewFooter(context);
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}
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@Override
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public void setAdapter(ListAdapter adapter) {
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// make sure XListViewFooter is the last footer view, and only add once.
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if (mIsFooterReady == false) {
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mIsFooterReady = true;
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addFooterView(mFooterView);
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}
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super.setAdapter(adapter);
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}
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/**
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* enable or disable pull down refresh feature.
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*
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* @param enable
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*/
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/*public void setPullRefreshEnable(boolean enable) {
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mEnablePullRefresh = enable;
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if (!mEnablePullRefresh) { // disable, hide the content
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mHeaderViewContent.setVisibility(View.INVISIBLE);
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} else {
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mHeaderViewContent.setVisibility(View.VISIBLE);
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}
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}*/
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/**
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* enable or disable pull up load more feature.
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*
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* @param enable
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*/
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public void setPullLoadEnable(boolean enable) {
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mEnablePullLoad = enable;
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if (!mEnablePullLoad) {
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mFooterView.hide();
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mFooterView.setOnClickListener(null);
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} else {
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mPullLoading = false;
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mFooterView.show();
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mFooterView.setState(WaterDropListViewFooter.STATE.normal);
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// both "pull up" and "click" will invoke load more.
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mFooterView.setOnClickListener(new OnClickListener() {
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@Override
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public void onClick(View v) {
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mFooterView.setEnabled(false);
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startLoadMore();
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}
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});
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}
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}
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/**
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* stop refresh, reset header view.
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*/
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public void stopRefresh() {
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if (mHeaderView.getCurrentState() == WaterDropListViewHeader.STATE.refreshing) {
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mHeaderView.updateState(WaterDropListViewHeader.STATE.end);
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if(!isTouchingScreen){
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resetHeaderHeight();
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}
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}else{
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throw new IllegalStateException("can not stop refresh while it is not refreshing!");
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}
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}
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/**
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* stop load more, reset footer view.
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*/
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public void stopLoadMore() {
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if (mPullLoading == true) {
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mPullLoading = false;
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mFooterView.setState(WaterDropListViewFooter.STATE.normal);
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}
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mFooterView.setEnabled(true);
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}
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private void invokeOnScrolling() {
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if (mScrollListener instanceof OnXScrollListener) {
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OnXScrollListener l = (OnXScrollListener) mScrollListener;
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l.onXScrolling(this);
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}
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}
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private void updateHeaderHeight(int height){
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if (mEnablePullRefresh) {
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if (mHeaderView.getCurrentState() == WaterDropListViewHeader.STATE.normal && height >= mHeaderView.getStretchHeight()) {
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//由normal变成stretch的逻辑：1、当前状态是normal；2、下拉头达到了stretchheight的高度
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mHeaderView.updateState(WaterDropListViewHeader.STATE.stretch);
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} else if(mHeaderView.getCurrentState() == WaterDropListViewHeader.STATE.stretch && height >= mHeaderView.getReadyHeight()){
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//由stretch变成ready的逻辑：1、当前状态是stretch；2、下拉头达到了readyheight的高度
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mHeaderView.updateState(WaterDropListViewHeader.STATE.ready);
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}else if (mHeaderView.getCurrentState() == WaterDropListViewHeader.STATE.stretch && height < mHeaderView.getStretchHeight()){
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// 由stretch变成normal的逻辑：1、当前状态是stretch；2、下拉头高度小于stretchheight的高度
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mHeaderView.updateState(WaterDropListViewHeader.STATE.normal);
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}else if(mHeaderView.getCurrentState() == WaterDropListViewHeader.STATE.end && height < 2){
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//由end变成normal的逻辑：1、当前状态是end；2、下拉头高度小于一个极小值
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mHeaderView.updateState(WaterDropListViewHeader.STATE.normal);
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}
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/*else{
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throw new IllegalStateException("WaterDropListView's state is illegal!");
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}*/
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}
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mHeaderView.setVisiableHeight(height);//动态设置HeaderView的高度
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}
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private void updateHeaderHeight(float delta) {
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int newHeight = (int) delta + mHeaderView.getVisiableHeight();
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updateHeaderHeight(newHeight);
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}
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/**
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* reset header view's height.
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* 重置headerheight的高度
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* 逻辑：1、如果状态处于非refreshing，则回滚到height=0状态2；2、如果状态处于refreshing，则回滚到stretchheight高度
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*/
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private void resetHeaderHeight() {
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int height = mHeaderView.getVisiableHeight();
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if (height == 0) {
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// not visible.
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return;
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}
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// refreshing and header isn't shown fully. do nothing.
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if (mHeaderView.getCurrentState() == WaterDropListViewHeader.STATE.refreshing && height <= mHeaderView.getStretchHeight()) {
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return;
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}
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int finalHeight = 0; // default: scroll back to dismiss header.
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// is refreshing, just scroll back to show all the header.
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if ((mHeaderView.getCurrentState() == WaterDropListViewHeader.STATE.ready ||mHeaderView.getCurrentState() == WaterDropListViewHeader.STATE.refreshing )&& height > mHeaderView.getStretchHeight()) {
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finalHeight = mHeaderView.getStretchHeight();
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}
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mScrollBack = ScrollBack.header;
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mScroller.startScroll(0, height, 0, finalHeight - height, SCROLL_DURATION);
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// trigger computeScroll
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invalidate();
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}
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private void updateFooterHeight(float delta) {
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int height = mFooterView.getBottomMargin() + (int) delta;
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if (mEnablePullLoad && !mPullLoading) {
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if (height > PULL_LOAD_MORE_DELTA) { // height enough to invoke load
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// more.
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mFooterView.setState(WaterDropListViewFooter.STATE.ready);
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} else {
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mFooterView.setState(WaterDropListViewFooter.STATE.normal);
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}
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}
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mFooterView.setBottomMargin(height);
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// setSelection(mTotalItemCount - 1); // scroll to bottom
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}
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private void resetFooterHeight() {
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int bottomMargin = mFooterView.getBottomMargin();
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if (bottomMargin > 0) {
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mScrollBack = ScrollBack.footer;
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mScroller.startScroll(0, bottomMargin, 0, -bottomMargin, SCROLL_DURATION);
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invalidate();
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}
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}
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private void startLoadMore() {
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mPullLoading = true;
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mFooterView.setState(WaterDropListViewFooter.STATE.loading);
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if (mListViewListener != null) {
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mListViewListener.onLoadMore();
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}
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}
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@Override
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public boolean onTouchEvent(MotionEvent ev) {
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if (mLastY == -1) {
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mLastY = ev.getRawY();
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}
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switch (ev.getAction()) {
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case MotionEvent.ACTION_DOWN:
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mLastY = ev.getRawY();
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isTouchingScreen = true;
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break;
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case MotionEvent.ACTION_MOVE:
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final float deltaY = ev.getRawY() - mLastY;
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mLastY = ev.getRawY();
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if (getFirstVisiblePosition() == 0 && (mHeaderView.getVisiableHeight() > 0 || deltaY > 0)) {
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// the first item is showing, header has shown or pull down.
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updateHeaderHeight(deltaY / OFFSET_RADIO);
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invokeOnScrolling();
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} else if (getLastVisiblePosition() == mTotalItemCount - 1 && (mFooterView.getBottomMargin() > 0 || deltaY < 0)) {
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// last item, already pulled up or want to pull up.
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updateFooterHeight(-deltaY / OFFSET_RADIO);
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}
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break;
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default:
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mLastY = -1; // reset
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isTouchingScreen = false;
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//TODO 存在bug：当两个if的条件都满足的时候，只能滚动一个，所以在reSetHeader的时候就不起作用了，一般就只会reSetFooter
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if (getFirstVisiblePosition() == 0) {
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resetHeaderHeight();
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}
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if (getLastVisiblePosition() == mTotalItemCount - 1) {
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// invoke load more.
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if (mEnablePullLoad && mFooterView.getBottomMargin() > PULL_LOAD_MORE_DELTA) {
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startLoadMore();
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}
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resetFooterHeight();
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}
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break;
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}
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return super.onTouchEvent(ev);
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}
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@Override
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public void computeScroll() {
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if (mScroller.computeScrollOffset()) {
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if (mScrollBack == ScrollBack.header) {
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updateHeaderHeight(mScroller.getCurrY());
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if(mScroller.getCurrY() < 2 && mHeaderView.getCurrentState() == WaterDropListViewHeader.STATE.end){
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//停止滚动了
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//逻辑：如果header范围进入了一个极小值内，且当前的状态是end，就把状态置成normal
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mHeaderView.updateState(WaterDropListViewHeader.STATE.normal);
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}
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} else {
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mFooterView.setBottomMargin(mScroller.getCurrY());
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}
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postInvalidate();
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invokeOnScrolling();
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}
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super.computeScroll();
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}
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@Override
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public void setOnScrollListener(OnScrollListener l) {
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mScrollListener = l;
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}
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@Override
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public void onScrollStateChanged(AbsListView view, int scrollState) {
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if (mScrollListener != null) {
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mScrollListener.onScrollStateChanged(view, scrollState);
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}
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}
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@Override
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public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
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// send to user's listener
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mTotalItemCount = totalItemCount;
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if (mScrollListener != null) {
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mScrollListener.onScroll(view, firstVisibleItem, visibleItemCount, totalItemCount);
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}
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}
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@Override
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public void notifyStateChanged(WaterDropListViewHeader.STATE oldState, WaterDropListViewHeader.STATE newState) {
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if(newState == WaterDropListViewHeader.STATE.refreshing){
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if(mListViewListener != null){
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mListViewListener.onRefresh();
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}
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}
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}
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public void setWaterDropListViewListener(IWaterDropListViewListener l) {
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mListViewListener = l;
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}
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/**
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* you can listen ListView.OnScrollListener or this one. it will invoke onXScrolling when header/footer scroll back.
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*/
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public interface OnXScrollListener extends OnScrollListener {
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public void onXScrolling(View view);
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}
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/**
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* implements this interface to get refresh/load more event.
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*/
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public interface IWaterDropListViewListener {
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public void onRefresh();
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public void onLoadMore();
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}
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}
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