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/**
* @file XListView.java
* @package me.maxwin.view
* @create Mar 18, 2012 6:28:41 PM
* @author Maxwin
* @description An ListView support (a) Pull down to refresh, (b) Pull up to load more.
* Implement IXListViewListener, and see stopRefresh() / stopLoadMore().
*/
package org.com.cctest.view;
import com.example.xlistview.R;
import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewTreeObserver.OnGlobalLayoutListener;
import android.view.animation.DecelerateInterpolator;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.RelativeLayout;
import android.widget.Scroller;
import android.widget.TextView;
public class XListView extends ListView implements OnScrollListener {
private float mLastY = -1; // save event y
private Scroller mScroller; // used for scroll back
private OnScrollListener mScrollListener; // user‘s scroll listener
// the interface to trigger refresh and load more.
private IXListViewListener mListViewListener;
// -- header view
private XListViewHeader mHeaderView;
// header view content, use it to calculate the Header‘s height. And hide it
// when disable pull refresh.
private RelativeLayout mHeaderViewContent;
private TextView mHeaderTimeView;
private int mHeaderViewHeight; // header view‘s height
private boolean mEnablePullRefresh = true;
private boolean mPullRefreshing = false; // is refreashing.
// -- footer view
private XListViewFooter mFooterView;
private boolean mEnablePullLoad;
private boolean mPullLoading;
private boolean mIsFooterReady = false;
// total list items, used to detect is at the bottom of listview.
private int mTotalItemCount;
// for mScroller, scroll back from header or footer.
private int mScrollBack;
private final static int SCROLLBACK_HEADER = 0;
private final static int SCROLLBACK_FOOTER = 1;
private final static int SCROLL_DURATION = 400; // scroll back duration
private final static int PULL_LOAD_MORE_DELTA = 50; // when pull up >= 50px
// at bottom, trigger
// load more.
private final static float OFFSET_RADIO = 1.8f; // support iOS like pull
// feature.
/**
* @param context
*/
public XListView(Context context) {
super(context);
initWithContext(context);
}
public XListView(Context context, AttributeSet attrs) {
super(context, attrs);
initWithContext(context);
}
public XListView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initWithContext(context);
}
private void initWithContext(Context context) {
mScroller = new Scroller(context, new DecelerateInterpolator());
// XListView need the scroll event, and it will dispatch the event to
// user‘s listener (as a proxy).
super.setOnScrollListener(this);
// init header view
mHeaderView = new XListViewHeader(context);
mHeaderViewContent = (RelativeLayout) mHeaderView
.findViewById(R.id.xlistview_header_content);
mHeaderTimeView = (TextView) mHeaderView
.findViewById(R.id.xlistview_header_time);
addHeaderView(mHeaderView);
// init footer view
mFooterView = new XListViewFooter(context);
// init header height
mHeaderView.getViewTreeObserver().addOnGlobalLayoutListener(
new OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
mHeaderViewHeight = mHeaderViewContent.getHeight();
getViewTreeObserver()
.removeGlobalOnLayoutListener(this);
}
});
}
@Override
public void setAdapter(ListAdapter adapter) {
// make sure XListViewFooter is the last footer view, and only add once.
if (mIsFooterReady == false) {
mIsFooterReady = true;
addFooterView(mFooterView);
}
super.setAdapter(adapter);
}
/**
* enable or disable pull down refresh feature.
*
* @param enable
*/
public void setPullRefreshEnable(boolean enable) {
mEnablePullRefresh = enable;
if (!mEnablePullRefresh) { // disable, hide the content
mHeaderViewContent.setVisibility(View.INVISIBLE);
} else {
mHeaderViewContent.setVisibility(View.VISIBLE);
}
}
/**
* enable or disable pull up load more feature.
*
* @param enable
*/
public void setPullLoadEnable(boolean enable) {
mEnablePullLoad = enable;
if (!mEnablePullLoad) {
mFooterView.hide();
mFooterView.setOnClickListener(null);
} else {
mPullLoading = false;
mFooterView.show();
mFooterView.setState(XListViewFooter.STATE_NORMAL);
// both "pull up" and "click" will invoke load more.
mFooterView.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
startLoadMore();
}
});
}
}
/**
* stop refresh, reset header view.
*/
public void stopRefresh() {
if (mPullRefreshing == true) {
mPullRefreshing = false;
resetHeaderHeight();
}
}
/**
* stop load more, reset footer view.
*/
public void stopLoadMore() {
if (mPullLoading == true) {
mPullLoading = false;
mFooterView.setState(XListViewFooter.STATE_NORMAL);
}
}
/**
* set last refresh time
*
* @param time
*/
public void setRefreshTime(String time) {
mHeaderTimeView.setText(time);
}
private void invokeOnScrolling() {
if (mScrollListener instanceof OnXScrollListener) {
OnXScrollListener l = (OnXScrollListener) mScrollListener;
l.onXScrolling(this);
}
}
private void updateHeaderHeight(float delta) {
mHeaderView.setVisiableHeight((int) delta
+ mHeaderView.getVisiableHeight());
if (mEnablePullRefresh && !mPullRefreshing) { // δ??????????????¼??
if (mHeaderView.getVisiableHeight() > mHeaderViewHeight) {
mHeaderView.setState(XListViewHeader.STATE_READY);
} else {
mHeaderView.setState(XListViewHeader.STATE_NORMAL);
}
}
setSelection(0); // scroll to top each time
}
/**
* reset header view‘s height.
*/
private void resetHeaderHeight() {
int height = mHeaderView.getVisiableHeight();
if (height == 0) // not visible.
return;
// refreshing and header isn‘t shown fully. do nothing.
if (mPullRefreshing && height <= mHeaderViewHeight) {
return;
}
int finalHeight = 0; // default: scroll back to dismiss header.
// is refreshing, just scroll back to show all the header.
if (mPullRefreshing && height > mHeaderViewHeight) {
finalHeight = mHeaderViewHeight;
}
mScrollBack = SCROLLBACK_HEADER;
mScroller.startScroll(0, height, 0, finalHeight - height,
SCROLL_DURATION);
// trigger computeScroll
invalidate();
}
private void updateFooterHeight(float delta) {
int height = mFooterView.getBottomMargin() + (int) delta;
if (mEnablePullLoad && !mPullLoading) {
if (height > PULL_LOAD_MORE_DELTA) { // height enough to invoke load
// more.
mFooterView.setState(XListViewFooter.STATE_READY);
} else {
mFooterView.setState(XListViewFooter.STATE_NORMAL);
}
}
mFooterView.setBottomMargin(height);
// setSelection(mTotalItemCount - 1); // scroll to bottom
}
private void resetFooterHeight() {
int bottomMargin = mFooterView.getBottomMargin();
if (bottomMargin > 0) {
mScrollBack = SCROLLBACK_FOOTER;
mScroller.startScroll(0, bottomMargin, 0, -bottomMargin,
SCROLL_DURATION);
invalidate();
}
}
private void startLoadMore() {
mPullLoading = true;
mFooterView.setState(XListViewFooter.STATE_LOADING);
if (mListViewListener != null) {
mListViewListener.onLoadMore();
}
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
if (mLastY == -1) {
mLastY = ev.getRawY();
}
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN:
mLastY = ev.getRawY();
break;
case MotionEvent.ACTION_MOVE:
final float deltaY = ev.getRawY() - mLastY;
mLastY = ev.getRawY();
if (getFirstVisiblePosition() == 0
&& (mHeaderView.getVisiableHeight() > 0 || deltaY > 0)) {
// the first item is showing, header has shown or pull down.
updateHeaderHeight(deltaY / OFFSET_RADIO);
invokeOnScrolling();
} else if (getLastVisiblePosition() == mTotalItemCount - 1
&& (mFooterView.getBottomMargin() > 0 || deltaY < 0)) {
// last item, already pulled up or want to pull up.
updateFooterHeight(-deltaY / OFFSET_RADIO);
}
break;
default:
mLastY = -1; // reset
if (getFirstVisiblePosition() == 0) {
// invoke refresh
if (mEnablePullRefresh
&& mHeaderView.getVisiableHeight() > mHeaderViewHeight) {
mPullRefreshing = true;
mHeaderView.setState(XListViewHeader.STATE_REFRESHING);
if (mListViewListener != null) {
mListViewListener.onRefresh();
}
}
resetHeaderHeight();
} else if (getLastVisiblePosition() == mTotalItemCount - 1) {
// invoke load more.
if (mEnablePullLoad
&& mFooterView.getBottomMargin() > PULL_LOAD_MORE_DELTA) {
startLoadMore();
}
resetFooterHeight();
}
break;
}
return super.onTouchEvent(ev);
}
@Override
public void computeScroll() {
if (mScroller.computeScrollOffset()) {
if (mScrollBack == SCROLLBACK_HEADER) {
mHeaderView.setVisiableHeight(mScroller.getCurrY());
} else {
mFooterView.setBottomMargin(mScroller.getCurrY());
}
postInvalidate();
invokeOnScrolling();
}
super.computeScroll();
}
@Override
public void setOnScrollListener(OnScrollListener l) {
mScrollListener = l;
}
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
if (mScrollListener != null) {
mScrollListener.onScrollStateChanged(view, scrollState);
}
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
// send to user‘s listener
mTotalItemCount = totalItemCount;
if (mScrollListener != null) {
mScrollListener.onScroll(view, firstVisibleItem, visibleItemCount,
totalItemCount);
}
}
public void setXListViewListener(IXListViewListener l) {
mListViewListener = l;
}
/**
* you can listen ListView.OnScrollListener or this one. it will invoke
* onXScrolling when header/footer scroll back.
*/
public interface OnXScrollListener extends OnScrollListener {
public void onXScrolling(View view);
}
/**
* implements this interface to get refresh/load more event.
*/
public interface IXListViewListener {
public void onRefresh();
public void onLoadMore();
}
}
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原文地址：http://www.cnblogs.com/bwandroid/p/5599491.html
