首先让我们看看封装得比较完善的IphoneTreeView：
代码如下:
public class IphoneTreeView extends ExpandableListView implements
OnScrollListener, OnGroupClickListener {
public IphoneTreeView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
registerListener();
}
public IphoneTreeView(Context context, AttributeSet attrs) {
super(context, attrs);
registerListener();
}
public IphoneTreeView(Context context) {
super(context);
registerListener();
}
/**
* Adapter 接口 . 列表必须实现此接口 .
*/
public interface IphoneTreeHeaderAdapter {
public static final int PINNED_HEADER_GONE = 0;
public static final int PINNED_HEADER_VISIBLE = 1;
public static final int PINNED_HEADER_PUSHED_UP = 2;
/**
* 获取 Header 的状态
*
* @param groupPosition
* @param childPosition
* @return
* PINNED_HEADER_GONE,PINNED_HEADER_VISIBLE,PINNED_HEADER_PUSHED_UP
* 其中之一
*/
int getTreeHeaderState(int groupPosition, int childPosition);
/**
* 配置 QQHeader, 让 QQHeader 知道显示的内容
*
* @param header
* @param groupPosition
* @param childPosition
* @param alpha
*/
void configureTreeHeader(View header, int groupPosition,
int childPosition, int alpha);
/**
* 设置组按下的状态
*
* @param groupPosition
* @param status
*/
void onHeadViewClick(int groupPosition, int status);
/**
* 获取组按下的状态
*
* @param groupPosition
* @return
*/
int getHeadViewClickStatus(int groupPosition);
}
private static final int MAX_ALPHA = 255;
private IphoneTreeHeaderAdapter mAdapter;
/**
* 用于在列表头显示的 View,mHeaderViewVisible 为 true 才可见
*/
private View mHeaderView;
/**
* 列表头是否可见
*/
private boolean mHeaderViewVisible;
private int mHeaderViewWidth;
private int mHeaderViewHeight;
public void setHeaderView(View view) {
mHeaderView = view;
AbsListView.LayoutParams lp = new AbsListView.LayoutParams(
ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.WRAP_CONTENT);
view.setLayoutParams(lp);
if (mHeaderView != null) {
setFadingEdgeLength(0);
}
requestLayout();
}
private void registerListener() {
setOnScrollListener(this);
setOnGroupClickListener(this);
}
/**
* 点击 HeaderView 触发的事件
*/
private void headerViewClick() {
long packedPosition = getExpandableListPosition(this
.getFirstVisiblePosition());
int groupPosition = ExpandableListView
.getPackedPositionGroup(packedPosition);
if (mAdapter.getHeadViewClickStatus(groupPosition) == 1) {
this.collapseGroup(groupPosition);
mAdapter.onHeadViewClick(groupPosition, 0);
} else {
this.expandGroup(groupPosition);
mAdapter.onHeadViewClick(groupPosition, 1);
}
this.setSelectedGroup(groupPosition);
}
private float mDownX;
private float mDownY;
/**
* 如果 HeaderView 是可见的 , 此函数用于判断是否点击了 HeaderView, 并对做相应的处理 , 因为 HeaderView
* 是画上去的 , 所以设置事件监听是无效的 , 只有自行控制 .
*/
@Override
public boolean onTouchEvent(MotionEvent ev) {
if (mHeaderViewVisible) {
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN:
mDownX = ev.getX();
mDownY = ev.getY();
if (mDownX