在旋转和背部恢复谷歌地图（V2）的地图状态（位置和标记）（图形页面中的片段） [英] Restoring map state (position and markers) of Google Maps (V2) on rotate and on back (MapView in Fragment)
问题描述
背景
我有一个更大的应用程序中，我有/有几个问题，新的谷歌地图API。我试着来形容它<一个href="http://stackoverflow.com/questions/16171619/markers-disapearing-from-mapview-v2-in-fragment-on-back">in一个不同的问题但因为它似乎太复杂，我决定开始一个新的项目，越简单越好，并尝试重现问题。所以在这儿呢。
I have a larger application in which I had/have several problems with new Google Maps API. I tried to describe it in a different question but since it seems too complex I decided to start a new project, as simple as possible and try to reproduce problems. So here it is.
情况
我用片段，并希望把图形页面里面。我不想使用 MapFragment 。示例项目我prepared可能不是很漂亮，但我试图使它尽可能简单，它必须包含原始应用程序的一些元素（再次简化）。
我有一个活动和我的自定义片段与图形页面的它补充说编程。该地图包含一些点/ 标记。点击一个标记的信息窗口显示，点击它会导致下一片段正在显示的内容（与更换（）函数）。
I'm using Fragments and want to put MapView inside. I don't want to use MapFragment. The sample project I prepared may be not very beautiful but I tried to make it as simple as possible and it had to contain some elements (again simplified) from the original app.
I have one Activity and my custom Fragment with MapView in it, added programatically. The Map contains some points/Markers. After clicking on a Marker the InfoWindow is shown and clicking on it causes next Fragment being shown (with replace() function) in content.
的问题
有两个问题我有：
-
在
地图与标记显示屏幕旋转的原因类不我的自定义解组错误MyMapPoint上课的时候发现了 - 我不知道为什么，什么意思
When the
MapwithMarkersis displayed screen rotation causesClass not found when unmarshallingerror with my customMyMapPointclass - I have no idea why and what it means.
我点击标记然后信息窗口。在此之后我preSS硬件后退按钮。现在我可以看到地图，但没有标记并集中在 0,0 点。
I click the Marker and then InfoWindow. After this I press hardware back button. Now I can see the Map but with no Markers and centered in 0,0 point.
的code
MainActivity
MainActivity
public class MainActivity extends FragmentActivity {
private ArrayList<MyMapPoint> mPoints = new ArrayList<MyMapPoint>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
mPoints.add(new MyMapPoint(1, new LatLng(20, 10),
"test point", "description", null));
mPoints.add(new MyMapPoint(2, new LatLng(10, 20),
"test point 2", "second description", null));
Fragment fragment = MyMapFragment.newInstance(mPoints);
getSupportFragmentManager().beginTransaction()
.add(R.id.contentPane, fragment).commit();
}
}
}
activity_main.xml
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/contentPane"
android:layout_width="fill_parent"
android:layout_height="fill_parent" />
map_fragment.xml
map_fragment.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<com.google.android.gms.maps.MapView
xmlns:map="http://schemas.android.com/apk/res-auto"
android:id="@+id/map"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>
MyMapFragment
MyMapFragment
public class MyMapFragment extends Fragment implements
OnInfoWindowClickListener {
public static final String KEY_POINTS = "points";
private MapView mMapView;
private GoogleMap mMap;
private HashMap<MyMapPoint, Marker> mPoints =
new HashMap<MyMapPoint, Marker>();
public static MyMapFragment newInstance(ArrayList<MyMapPoint> points) {
MyMapFragment fragment = new MyMapFragment();
Bundle args = new Bundle();
args.putParcelableArrayList(KEY_POINTS, points);
fragment.setArguments(args);
return fragment;
}
@Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
mMapView.onSaveInstanceState(outState);
MyMapPoint[] points = mPoints.keySet().toArray(
new MyMapPoint[mPoints.size()]);
outState.putParcelableArray(KEY_POINTS, points);
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (savedInstanceState == null) {
Bundle extras = getArguments();
if ((extras != null) && extras.containsKey(KEY_POINTS)) {
for (Parcelable pointP : extras.getParcelableArrayList(KEY_POINTS)) {
mPoints.put((MyMapPoint) pointP, null);
}
}
} else {
MyMapPoint[] points = (MyMapPoint[]) savedInstanceState
.getParcelableArray(KEY_POINTS);
for (MyMapPoint point : points) {
mPoints.put(point, null);
}
}
}
@Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
View layout = inflater.inflate(R.layout.map_fragment, container, false);
mMapView = (MapView) layout.findViewById(R.id.map);
return layout;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
mMapView.onCreate(savedInstanceState);
setUpMapIfNeeded();
addMapPoints();
}
@Override
public void onPause() {
mMapView.onPause();
super.onPause();
}
@Override
public void onResume() {
super.onResume();
setUpMapIfNeeded();
mMapView.onResume();
}
@Override
public void onDestroy() {
mMapView.onDestroy();
super.onDestroy();
}
public void onLowMemory() {
super.onLowMemory();
mMapView.onLowMemory();
};
private void setUpMapIfNeeded() {
if (mMap == null) {
mMap = ((MapView) getView().findViewById(R.id.map)).getMap();
if (mMap != null) {
setUpMap();
}
}
}
private void setUpMap() {
mMap.setOnInfoWindowClickListener(this);
addMapPoints();
}
private void addMapPoints() {
if (mMap != null) {
HashMap<MyMapPoint, Marker> toAdd =
new HashMap<MyMapPoint, Marker>();
for (Entry<MyMapPoint, Marker> entry : mPoints.entrySet()) {
Marker marker = entry.getValue();
if (marker == null) {
MyMapPoint point = entry.getKey();
marker = mMap.addMarker(point.getMarkerOptions());
toAdd.put(point, marker);
}
}
mPoints.putAll(toAdd);
}
}
@Override
public void onInfoWindowClick(Marker marker) {
Fragment fragment = DetailsFragment.newInstance();
getActivity().getSupportFragmentManager().beginTransaction()
.replace(R.id.contentPane, fragment)
.addToBackStack(null).commit();
}
public static class MyMapPoint implements Parcelable {
private static final int CONTENTS_DESCR = 1;
public int objectId;
public LatLng latLng;
public String title;
public String snippet;
public MyMapPoint(int oId, LatLng point,
String infoTitle, String infoSnippet, String infoImageUrl) {
objectId = oId;
latLng = point;
title = infoTitle;
snippet = infoSnippet;
}
public MyMapPoint(Parcel in) {
objectId = in.readInt();
latLng = in.readParcelable(LatLng.class.getClassLoader());
title = in.readString();
snippet = in.readString();
}
public MarkerOptions getMarkerOptions() {
return new MarkerOptions().position(latLng)
.title(title).snippet(snippet);
}
@Override
public int describeContents() {
return CONTENTS_DESCR;
}
@Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeInt(objectId);
dest.writeParcelable(latLng, 0);
dest.writeString(title);
dest.writeString(snippet);
}
public static final Parcelable.Creator<MyMapPoint> CREATOR =
new Parcelable.Creator<MyMapPoint>() {
public MyMapPoint createFromParcel(Parcel in) {
return new MyMapPoint(in);
}
public MyMapPoint[] newArray(int size) {
return new MyMapPoint[size];
}
};
}
}
如果你需要看看任何其他文件 - 让我知道。 这里你可以找到一个完整的项目，你就必须把自己的地图API密钥 AndroidManifest的.xml 文件。
If you need to take a look at any other file - let me know. Here you can find a complete project, you just have to put your own Maps API KEY in AndroidManifest.xml file.
修改
我设法让这个例子更简单，更新了code以上。
I managed to make the example even more simple and updated the code above.
推荐答案
下面是我的修复程序的第一个问题：
Here is my fix to the first problem:
看来，地图正在尝试unparcel所有的包，而不仅仅是它的时候我叫 mMap.onCreate（savedInstanceState）<自己的信息/ code>，它有问题，如果我用我的自定义 Parcelable 类。这为我工作的溶液从 savedInstanceState 删除我的演员，只要我用他们 - 之前，我打电话地图的的onCreate（）。我做它 savedInstanceState.remove（MY_KEY）。另一件事我所要做的就是打电话给 mMap.onSaveInstanceState（）添加自己的信息 outState 之前片段的 的onSaveInstanceState（包outState）的功能。
It seems that Map is trying to unparcel all the bundle, not just it's own information when I call mMap.onCreate(savedInstanceState) and it has problem with it if I'm using my custom Parcelable class. The solution that worked for me was removing my extras from savedInstanceState as soon as I used them - before I call Map's onCreate(). I do it with savedInstanceState.remove(MY_KEY). Another thing I had to do was to call mMap.onSaveInstanceState() before adding my own information to outState in Fragment's onSaveInstanceState(Bundle outState) function.
这就是我如何处理第二个：
And here's how I handled the second one:
我简单的示例项目到裸露的骨头。我加入原标记来映射，如果我与另一个地图替换片段再单击了背我仍然有调零的地图。
所以，我做了两件事：
I simplified the example project to the bare bones. I was adding raw Markers to the map and if I replace the Fragment with map with another one then after clicking "back" I still got "nulled" map.
So I did two things:
- 节约
CameraPosition在的onPause（）功能在onResume其恢复（） -
MMAP在的onPause设置为空（）所以当片段返回时，标记再次由addMapPoints（）函数添加（我不得不改变它一点点，因为我是保存和检查标记的id）。
- saving
CameraPositioninonPause()function to restore it inonResume() - setting
mMapto null inonPause()so when theFragmentcomes back, theMarkersare added again by theaddMapPoints()function (I had to change it a little bit since I was saving and checkingMarkersid's).
下面是code样品：</ P>
Here are code samples:
private CameraPosition cp;
...
public void onPause() {
mMapView.onPause();
super.onPause();
cp = mMap.getCameraPosition();
mMap = null;
}
...
public void onResume() {
super.onResume();
setUpMapIfNeeded();
mMapView.onResume();
if (cp != null) {
mMap.moveCamera(CameraUpdateFactory.newCameraPosition(cp));
cp = null;
}
}
和更新 onResume摄像机的位置（）我不得不手动初始化地图。我做到了 setUpMap（）：
And to update the camera position in onResume() I had to manually initialize maps. I did it in setUpMap():
private void setUpMap() {
try {
MapsInitializer.initialize(getActivity());
} catch (GooglePlayServicesNotAvailableException e) {
}
mMap.setOnInfoWindowClickListener(this);
mMap.setOnMapLongClickListener(this);
addMapPoints();
}
我认识到，这些都不是真正的解决方案 - 只是覆盖，但它是最好的，我可以现在做的项目必须继续下去。如果有人发现清洁修复我会感谢你让我了解他们。
I realize that those aren't real solutions - just overrides but it's the best I can do for now and the project must go on. If anyone finds cleaner fixes I'll be grateful for letting me know about them.
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