private void updateHeaderHeight(float delta) {
mHeaderView.setVisiableHeight((int) delta + mHeaderView.getVisiableHeight());
if (mEnablePullRefresh && !mPullRefreshing) { // 未处于刷新状态，更新箭头
if (mHeaderView.getVisiableHeight() > mHeaderViewHeight) {
mHeaderView.setState(NewListViewHeader.STATE_READY);
} else {
mHeaderView.setState(NewListViewHeader.STATE_NORMAL);
}
}
setSelection(0); // scroll to top each time
}
@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(NewListViewHeader.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);
}