MapActivity在TabHost片段选项卡切换后消失 [英] MapActivity in TabHost Fragment disappearing after tab switch

问题描述

我想在一组选项卡中显示地图，用碎片。 我遇到的问题是，如果用户导航到另一个片段，然后再在地图的活动消失。 我怎样才能在一个tabhost显示片段一MapActivity？

I'm trying to display a map in a set of tabs, using fragments. The problem I'm having is the map activity disappears if the user navigates to another fragment, then back. How can I display a MapActivity in fragments in a tabhost?

其基础是围绕如何整合片段一个MapActivity的许多问题（见图形页面中的一个片段（蜂窝））

The basis for this is from the numerous questions around how to integrate a MapActivity with fragments (see MapView in a Fragment (Honeycomb))

MainTabActivity具有tabhost并使用FragmentManager显示在选项卡中的片段。 MapFragment具有tabhost并使用它来显示一个MapActivity。
MapFragment确实使用LocalActivityManager来propogate生命周期事件的所包含的活动。

MainTabActivity has a tabhost and uses FragmentManager to display Fragments in the tabs. MapFragment has a tabhost and uses it to display a MapActivity.
MapFragment does use LocalActivityManager to propogate lifecycle events to the the contained activity.

所以MapFragment：

So MapFragment:

   public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.map_fragment, container, false);
        mTabHost = (TabHost) view.findViewById(android.R.id.tabhost);
        mTabHost.setup(getLocalActivityManager());
        Intent intent = new Intent(getActivity(), MapActivityWrapper.class);
//        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);//does nothing
        TabHost.TabSpec tab = mTabHost.newTabSpec("map")
                .setIndicator("map")
                .setContent(intent);
        mTabHost.addTab(tab);
        return view;
    }

MapFragment布局：

MapFragment layout:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="fill_parent"
              android:layout_height="fill_parent"
              android:orientation="vertical">
    <TabHost xmlns:android="http://schemas.android.com/apk/res/android"
             android:id="@android:id/tabhost"
             android:layout_width="fill_parent"
             android:layout_height="fill_parent">
        <LinearLayout android:orientation="vertical"
                android:layout_width="fill_parent"
                android:layout_height="fill_parent">
            <TabWidget android:id="@android:id/tabs"
                    android:visibility="gone"
                    android:layout_width="fill_parent"
                    android:layout_height="wrap_content"/>
            <FrameLayout android:id="@android:id/tabcontent"
                    android:layout_width="fill_parent"
                    android:layout_height="fill_parent"/>
        </LinearLayout>
    </TabHost>
</LinearLayout>

在code在MainTabActivity改变标签的内容：

The code in MainTabActivity for changing the tab contents:

private void updateTab(String oldId, String tabId) {
    FragmentManager fm = getSupportFragmentManager();
    Fragment old = fm.findFragmentByTag(oldId);
    Fragment selected = fm.findFragmentByTag(tabId);
    FragmentTransaction ft = fm.beginTransaction();
    boolean added = false;
    if (selected == null) {
        selected = createFragment(tabId);
    } else {
        try {
            ft.remove(selected);
        } catch (Exception e) {
            ft.add(android.R.id.tabcontent, selected, tabId);
            added = true;
            //exception for removing an unadded fragment... why throw an exception?
        }
    }
    if (old != null) ft.remove(old);
    if (!added) ft.replace(android.R.id.tabcontent, selected, tabId);
    if (!creating && !backStackProcessing) ft.addToBackStack(null);//member vars
    ft.commit();
}

MainTabActivity布局（删除了一堆不相关的布局）：

MainTabActivity layout (deleted a bunch of unrelated layout):

<TabHost xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@android:id/tabhost"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:background="#EFEFEF">
    <RelativeLayout android:layout_width="fill_parent"
            android:layout_height="fill_parent">
        <FrameLayout android:id="@android:id/tabcontent"
                android:layout_gravity="top"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:background="@color/app_default_bg"
                android:layout_above="@+id/ad_region"
                android:layout_below="@+id/quick_action_region">
            <FrameLayout android:id="@+id/tab1"
                    android:layout_width="fill_parent"
                    android:layout_height="fill_parent"/>
            <FrameLayout android:id="@+id/tab2"
                    android:layout_width="fill_parent"
                    android:layout_height="fill_parent"/>
            <FrameLayout android:id="@+id/map_tab"
                    android:layout_width="fill_parent"
                    android:layout_height="fill_parent"/>
            <FrameLayout android:id="@+id/tab3"
                    android:layout_width="fill_parent"
                    android:layout_height="fill_parent"/>
        </FrameLayout>
        <TabWidget android:layout_width="fill_parent"
                   android:id="@android:id/tabs"
                   android:layout_height="wrap_content"
                   android:layout_alignParentBottom="true"
                   android:layout_alignParentLeft="true"/>
    </RelativeLayout>
</TabHost>

再次 - 我遇到的问题是，如果用户导航到另一个片段，然后再在地图的活动消失。 我怎样才能在一个tabhost显示片段一MapActivity？

Again - The problem I'm having is the map activity disappears if the user navigates to another fragment, then back. How can I display a MapActivity in fragments in a tabhost?

谢谢了。

推荐答案

我的工作解决此问题如下...

I worked around this issue as follows...

我有一个类级别的变量：

I had a class level variable:

private View mMapViewContainer;

我创建了一个包含地图，如下所示的选项卡（其中MyMapActivity在标签中显示的MapActivity和mTabHost是TabHost）在我的片段onViewCreated方式：

I created the tab containing the map as follows (where MyMapActivity is the MapActivity displayed in the tab and mTabHost is the TabHost) in the onViewCreated method of my Fragment:

// Map tab
Intent intent = new Intent(getActivity(), MyMapActivity.class);
Window window = mLocalActivityManager.startActivity(MAP_ACTIVITY_TAG, intent);
mMapViewContainer = window.getDecorView();
mMapViewContainer.setVisibility(View.VISIBLE);
mMapViewContainer.setFocusableInTouchMode(true);
((ViewGroup) mMapViewContainer).setDescendantFocusability(ViewGroup.FOCUS_AFTER_DESCENDANTS);

View tab = getActivity().getLayoutInflater().inflate(R.layout.tab_background, null);
((TextView) tab.findViewById(R.id.tv_tab_title)).setText(getResources().getString(R.string.map));
TabSpec tabSpec = mTabHost.newTabSpec(MAP_TAB_TAG).setIndicator(tab).setContent(new TabContentFactory() {

    @Override
    public View createTabContent(String tag) {
        return mMapViewContainer;
    }
});
mTabHost.addTab(tabSpec);

然后在片段的onStop（）方法，我做了以下内容：

And then in the fragments onStop() method I did the following:

@Override
public void onStop() {
    super.onStop();

    ((ViewGroup) mMapViewContainer.getParent()).removeView(mMapViewContainer);
}

现在当用户导航到另一片段和重新显示在地图上，然后回

Now the map is re-displayed when the user navigates to another fragment and then back.

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