页面采用了两层，后面一层为Viewpager，前面为悬浮头与tab切换，在这大家应该都想到了会怎么样实现，Viewpager中添加已经fragment，每个fragment里面加入一个可下拉刷新的Listview，根据ListView的滑动来控制前一帧页面的位置。
来看看页面代码吧，MainAcitivity.java
public class MainActivity extends ActionBarActivity implements OnPageChangeListener, ScrollTabHolder {
private PagerSlidingTabStrip tabs;
private ViewPager viewPager;
private SlidingPagerAdapter adapter;
private LinearLayout header;
private int headerHeight;
private int headerTranslationDis;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_activity);
getHeaderHeight();
findViews();
setupPager();
setupTabs();
}
private void findViews() {
tabs = (PagerSlidingTabStrip) findViewById(R.id.show_tabs);
viewPager = (ViewPager) findViewById(R.id.pager);
header = (LinearLayout) findViewById(R.id.header);
}
private void getHeaderHeight() {
headerHeight = getResources().getDimensionPixelSize(R.dimen.max_header_height);
headerTranslationDis = -getResources().getDimensionPixelSize(R.dimen.header_offset_dis);
}
private void setupPager() {
adapter = new SlidingPagerAdapter(getSupportFragmentManager(), this, viewPager);
adapter.setTabHolderScrollingListener(this);//控制页面上滑
viewPager.setOffscreenPageLimit(adapter.getCacheCount());
viewPager.setAdapter(adapter);
viewPager.setOnPageChangeListener(this);
}
private void setupTabs() {
tabs.setShouldExpand(true);
tabs.setIndicatorColorResource(R.color.color_purple_bd6aff);
tabs.setUnderlineColorResource(R.color.color_purple_bd6aff);
tabs.setCheckedTextColorResource(R.color.color_purple_bd6aff);
tabs.setViewPager(viewPager);
}
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
tabs.onPageScrolled(position, positionOffset, positionOffsetPixels);
}
@Override
public void onPageSelected(int position) {
tabs.onPageSelected(position);
reLocation = true;
SparseArrayCompat<ScrollTabHolder> scrollTabHolders = adapter.getScrollTabHolders();
ScrollTabHolder currentHolder = scrollTabHolders.valueAt(position);
if (NEED_RELAYOUT) {
currentHolder.adjustScroll((int) (header.getHeight() + headerTop));// 修正滚出去的偏移量
} else {
currentHolder.adjustScroll((int) (header.getHeight() + ViewHelper.getTranslationY(header)));// 修正滚出去的偏移量
}
}
@Override
public void onPageScrollStateChanged(int state) {
tabs.onPageScrollStateChanged(state);
}
@Override
public void adjustScroll(int scrollHeight) {
}
private boolean reLocation = false;
private int headerScrollSize = 0;
public static final boolean NEED_RELAYOUT = Integer.valueOf(Build.VERSION.SDK).intValue() < Build.VERSION_CODES.HONEYCOMB;
private int headerTop = 0;
// 刷新头部显示时，没有onScroll回调，只有当刷新时会有
@Override
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount,
int pagePosition) {
if (viewPager.getCurrentItem() != pagePosition) {
return;
}
if (headerScrollSize == 0 && reLocation) {
reLocation = false;
return;
}
reLocation = false;
int scrollY = Math.max(-getScrollY(view), headerTranslationDis);
if (NEED_RELAYOUT) {
headerTop = scrollY;
header.post(new Runnable() {
@Override
public void run() {
Log.e("Main", "scorry1="+ headerTop);
header.layout(0, headerTop, header.getWidth(), headerTop + header.getHeight());
}
});
} else {
ViewHelper.setTranslationY(header, scrollY);
}
}
/**
* 主要算这玩意，PullToRefreshListView插入了一个刷新头部，因此要根据不同的情况计算当前的偏移量</br>
*
* 当刷新时： 刷新头部显示，因此偏移量要加上刷新头的数值 未刷新时： 偏移量不计算头部。
*
* firstVisiblePosition >1时，listview中的项开始显示，姑且认为每一项等高来计算偏移量（其实只要显示一个项，向上偏移
* 量已经大于头部的最大偏移量，因此不准确也没有关系）
*
* @param view
* @return
*/
public int getScrollY(AbsListView view) {
View c = view.getChildAt(0);
if (c == null) {
return 0;
}
int top = c.getTop();
int firstVisiblePosition = view.getFirstVisiblePosition();
if (firstVisiblePosition == 0) {
return -top + headerScrollSize;
} else if (firstVisiblePosition == 1) {
return -top;
} else {
return -top + (firstVisiblePosition - 2) * c.getHeight() + headerHeight;
}
}
// 与onHeadScroll互斥，不能同时执行
@Override
public void onHeaderScroll(boolean isRefreashing, int value, int pagePosition) {
if (viewPager.getCurrentItem() != pagePosition) {
return;
}
headerScrollSize = value;
if (NEED_RELAYOUT) {
header.post(new Runnable() {
@Override
public void run() {
Log.e("Main", "scorry="+ (-headerScrollSize));
header.layout(0, -headerScrollSize, header.getWidth(), -headerScrollSize + header.getHeight());
}
});
}else{
ViewHelper.setTranslationY(header, -value);
}
}
}
