旋转时回收Android地图V2 SupportMapFragment [英] Recycle Android Maps V2 SupportMapFragment when rotating

问题描述

我期待改善SupportMapFragment的性能时，该设备被旋转。看来，如果该片段必须重新创建。我不知道这一点，但是当设备旋转的地图图块必须重新加载。它将使意义从性能的角度来对整个mapfragment保留和再利用，而不必重新实例片段。任何洞察到这将是AP preciated。

我声明在XML中SupportMapFragment并使用SetupMapIfNeeded（），如API文档描述。

 私人无效setUpMapIfNeeded（）{
    //做一个空检查确认，我们还没有实例化
    // 地图。
    如果（MMAP == NULL）{
        //尝试获取来自SupportMapFragment地图。
        MMAP =（（SupportMapFragment）getSupportFragmentManager（）
                .findFragmentById（R.id.map））的GetMap（）。
        //检查如果我们成功取得地图。
        如果（MMAP！= NULL）{
            setUpMap（）;
        }
    }
}
 

解决方案

退房RetainMapActivity类从样品。工程就像一个魅力。这里是：

 公共类RetainMapActivity扩展FragmentActivity {

私人GoogleMap的MMAP;

@覆盖
保护无效的onCreate（包savedInstanceState）{
    super.onCreate（savedInstanceState）;
    的setContentView（R.layout.basic_demo）;

    SupportMapFragment mapFragment =（SupportMapFragment）getSupportFragmentManager（）
            .findFragmentById（R.id.map）;

    如果（savedInstanceState == NULL）{
        //本次活动的第一个化身。
        mapFragment.setRetainInstance（真正的）;
    } 其他 {
        //转世活动。得到的地图是在previous相同的地图实例
        //活动的生命周期。没有必要重新初始化它。
        MMAP = mapFragment.getMap（）;
    }
    setUpMapIfNeeded（）;
}

@覆盖
保护无效onResume（）{
    super.onResume（）;
    setUpMapIfNeeded（）;
}

私人无效setUpMapIfNeeded（）{
    如果（MMAP == NULL）{
        MMAP =（（SupportMapFragment）getSupportFragmentManager（）。findFragmentById（R.id.map））
                .getMap（）;
        如果（MMAP！= NULL）{
            setUpMap（）;
        }
    }
}

私人无效setUpMap（）{
    mMap.addMarker（新MarkerOptions（）位置（新的经纬度（0，0））标题（标记））;
}
 

}

I am looking to improve the performance of the SupportMapFragment when the device is rotated. It seems as if the fragment must be recreated. I am not sure of this, however when the device is rotated the map tiles must be reloaded. It would make sense from a performance perspective to have the entire mapfragment retained and reused without having to re-instantiate the fragment. Any insight into this would be appreciated.

I am declaring the SupportMapFragment in xml and using the SetupMapIfNeeded() as described in the api docs.

private void setUpMapIfNeeded() {
    // Do a null check to confirm that we have not already instantiated the
    // map.
    if (mMap == null) {
        // Try to obtain the map from the SupportMapFragment.
        mMap = ((SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map)).getMap();
        // Check if we were successful in obtaining the map.
        if (mMap != null) {
            setUpMap();
        }
    }
}

解决方案

Check out the RetainMapActivity class from the samples. Works like a charm. Here is is:

public class RetainMapActivity extends FragmentActivity {

private GoogleMap mMap;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.basic_demo);

    SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
            .findFragmentById(R.id.map);

    if (savedInstanceState == null) {
        // First incarnation of this activity.
        mapFragment.setRetainInstance(true);
    } else {
        // Reincarnated activity. The obtained map is the same map instance in the previous
        // activity life cycle. There is no need to reinitialize it.
        mMap = mapFragment.getMap();
    }
    setUpMapIfNeeded();
}

@Override
protected void onResume() {
    super.onResume();
    setUpMapIfNeeded();
}

private void setUpMapIfNeeded() {
    if (mMap == null) {
        mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map))
                .getMap();
        if (mMap != null) {
            setUpMap();
        }
    }
}

private void setUpMap() {
    mMap.addMarker(new MarkerOptions().position(new LatLng(0, 0)).title("Marker"));
}

}

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