package tv.danmaku.android.util;
import java.util.HashMap;
import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentTransaction;
import android.view.View;
import android.widget.TabHost;
/**
* This is a helper class that implements a generic mechanism for associating
* fragments with the tabs in a tab host. It relies on a trick. Normally a tab
* host has a simple API for supplying a View or Intent that each tab will show.
* This is not sufficient for switching between fragments. So instead we make
* the content part of the tab host 0dp high (it is not shown) and the
* TabManager supplies its own dummy view to show as the tab content. It listens
* to changes in tabs, and takes care of switch to the correct fragment shown in
* a separate content area whenever the selected tab changes.
*/
public class TabManager implements TabHost.OnTabChangeListener {
private final FragmentActivity mActivity;
private final TabHost mTabHost;
private final int mContainerId;
private final HashMap<String, TabInfo> mTabs = new HashMap<String, TabInfo>();
TabInfo mLastTab;
static final class TabInfo {
private final String tag;
private final Class<?> clss;
private final Bundle args;
private Fragment fragment;
TabInfo(String _tag, Class<?> _class, Bundle _args) {
tag = _tag;
clss = _class;
args = _args;
}
}
static class DummyTabFactory implements TabHost.TabContentFactory {
private final Context mContext;
public DummyTabFactory(Context context) {
mContext = context;
}
@Override
public View createTabContent(String tag) {
View v = new View(mContext);
v.setMinimumWidth(0);
v.setMinimumHeight(0);
return v;
}
}
public TabManager(FragmentActivity activity, TabHost tabHost,
int containerId) {
mActivity = activity;
mTabHost = tabHost;
mContainerId = containerId;
mTabHost.setOnTabChangedListener(this);
}
public void addTab(TabHost.TabSpec tabSpec, Class<?> clss, Bundle args) {
tabSpec.setContent(new DummyTabFactory(mActivity));
String tag = tabSpec.getTag();
TabInfo info = new TabInfo(tag, clss, args);
// Check to see if we already have a fragment for this tab, probably
// from a previously saved state. If so, deactivate it, because our
// initial state is that a tab isn't shown.
info.fragment = mActivity.getSupportFragmentManager()
.findFragmentByTag(tag);
if (info.fragment != null && !info.fragment.isDetached()) {
FragmentTransaction ft = mActivity.getSupportFragmentManager()
.beginTransaction();
ft.detach(info.fragment);
ft.commit();
}
mTabs.put(tag, info);
mTabHost.addTab(tabSpec);
}
@Override
public void onTabChanged(String tabId) {
TabInfo newTab = mTabs.get(tabId);
if (mLastTab != newTab) {
FragmentTransaction ft = mActivity.getSupportFragmentManager()
.beginTransaction();
if (mLastTab != null) {
if (mLastTab.fragment != null) {
ft.detach(mLastTab.fragment);
}
}
if (newTab != null) {
if (newTab.fragment == null) {
newTab.fragment = Fragment.instantiate(mActivity,
newTab.clss.getName(), newTab.args);
ft.add(mContainerId, newTab.fragment, newTab.tag);
} else {
ft.attach(newTab.fragment);
}
}
mLastTab = newTab;
ft.commit();
mActivity.getSupportFragmentManager().executePendingTransactions();
}
}
}