android - Google Maps API 2 MapView 未更新

Question

我在 Android 应用程序中显示 Google Maps API v2 MapView，但奇怪的是它没有以一致的方式正确更新。我正在使用 GPS 更新 map 位置(尝试了 LocationManager 和 LocationClient)，虽然 map 移动到该位置，但大约 50% 的时间要么街道名称图层无法更新，要么有一个模糊/模糊的部分失败更新——直到我手动拖动(滚动) map 。然后整个 map 立即更新。我已经剥离了应用程序中的大量处理，以查看我是否以某种方式阻止了刷新，但这并没有什么不同。

我在 onCameraChange 中插入了一个 mapView.invalidate() 调用，但奇怪的是，这似乎使问题更容易发生(尽管仍然不是 100% 的时间)。

我正在按照 MapView 的要求实现所有 Activity 回调。

有人在 Android 上使用 Google Map API v2 遇到过这样的问题吗？如果是，您是否确定了原因以及您是如何解决的？

Answer 1

可以这么说，你必须让 map 呼吸。

将animateCamera 与CancelableCallback 一起使用，然后当动画完成时，您将收到一个回调onFinish() 开始下一个动画.

public class KmlReader extends ActionBarActivity implements
    CancelableCallback {


@Override
public void onFinish() {
    startAnimation(); // start next map movement
}


@Override
public void onCancel() {
    //Called when user interacts with the map while it is moving.
}


public void startAnimation(){

cameraPosition = mMap.getCameraPosition();    
LatLng ll = new LatLng(expectedLocation.getLatitude(),
                    expectedLocation.getLongitude());
            cb.zoom(cameraPosition.zoom)
            // previous camera tilt
                    .tilt(cameraPosition.tilt)
                    // new expected destination
                    .target(ll)
                    // north up or heading view
                    .bearing((isHeading) ? bearing : 0f);
            cameraPosition = cb.build();
            CameraUpdate update = CameraUpdateFactory
                    .newCameraPosition(cameraPosition);
            mMap.animateCamera(update, working_interval, this);
}

* 编辑这是我现在正在处理的代码。*它使用异步任务进行计算。我已经对它进行了步行测试，但尚未在车辆中进行过测试。

private static CameraPosition currentCameraPosition;
private static com.google.android.gms.maps.model.CameraPosition.Builder cameraPositionBuilder;
private volatile CameraUpdate nextCameraUpdate;
// updates 
private static final long UPDATE_INTERVAL = 2500;
// fastest 
private static final int FASTEST_INTERVAL = 2500;
private static int working_interval = 5000; 
private volatile boolean isAnimating;


// Define the callback method that receives location updates
@SuppressLint("NewApi")
@Override
public void onLocationChanged(Location location) {
    Log.d("test", Boolean.toString(isAnimating)  +" onlocation");
    currentCameraPosition = mMap.getCameraPosition();

    NewCameraUpdateTask newCameraUpdateTask = new NewCameraUpdateTask();

// This task must run async
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
    newCameraUpdateTask.executeOnExecutor(
            AsyncTask.THREAD_POOL_EXECUTOR, location);
} else {
    newCameraUpdateTask.execute(location);
}
    // speed display
    setMetersPerSecond(location.getSpeed());
}

// create a newCameraUpdate to move the map with
private class NewCameraUpdateTask extends
        AsyncTask<Location, Void, CameraUpdate> {

    @Override
    protected CameraUpdate doInBackground(Location... params) {
        Location workingLocation = null;
        CameraUpdate newCameraUpdate = null;

        float bearing = 0f;
        float speed = 0f;

        for (Location mlocation : params) {
            speed = mlocation.getSpeed();

            // camera position is saved before the start of each animation.
            LatLng ll;

        if (!mlocation.hasBearing() || speed == 0) {
            workingLocation = mlocation;
            // previous bearing
        } else {
            // current bearing
            bearing = mlocation.getBearing();
            // calculate the age of the location
            // atempt for animation to end a little bit past when
            // the
            // next
            // location arrives.
            // (location.getSpeed()m/s)(1/1000 interval seconds)(
            // 1/1000
            // km/m)
            // (1/6371 radians/km) = radians/6371000000.0
            double expectedDistance = working_interval / 6371000000.0
                    * speed;

            // latitude in Radians
            double currentLatitude = Math.toRadians(mlocation
                    .getLatitude());
            // longitude in Radians
            double currentlongitude = Math.toRadians(mlocation
                    .getLongitude());

            double calcBearing = Math.toRadians(bearing);

            // the camera position is needed so I can put in the
            // previous camera bearing when the location has no
            // bearing. This should prevent the map from
            // zooming to north when the device stops moving.

            // calculate the expected latitude and longitude based
            // on
            // staring
            // location
            // , bearing, and distance
            double sincurrentLatitude = Math.sin(currentLatitude);
            double coscurrentLatitude = Math.cos(currentLatitude);
            double cosexpectedDistance = Math.cos(expectedDistance);
            double sinexpectedDistance = Math.sin(expectedDistance);

            double expectedLatitude = Math.asin(sincurrentLatitude
                    * cosexpectedDistance + coscurrentLatitude
                    * sinexpectedDistance * Math.cos(calcBearing));
            double a = Math.atan2(
                    Math.sin(calcBearing) * sinexpectedDistance
                            * coscurrentLatitude,
                    cosexpectedDistance - sincurrentLatitude
                            * Math.sin(expectedLatitude));
            double expectedLongitude = currentlongitude + a;
            expectedLongitude = (expectedLongitude + PI3) % PI2 - PI;

            // convert to degrees for the expected destination
            double expectedLongitudeDestination = Math
                    .toDegrees(expectedLongitude);
            double expectedLatitudeDestination = Math
                    .toDegrees(expectedLatitude);

            mlocation.setLatitude(expectedLatitudeDestination);
            mlocation.setLongitude(expectedLongitudeDestination);
            workingLocation = mlocation;

        }
        break;
    }

    if (workingLocation != null) {
        if (workingLocation.hasBearing()) {
            bearing = workingLocation.getBearing();
        } else {
            bearing = currentCameraPosition.bearing;
        }
        LatLng ll = new LatLng(workingLocation.getLatitude(),
                workingLocation.getLongitude());
        cameraPositionBuilder.zoom(currentCameraPosition.zoom)
        // previous camera tilt
                .tilt(currentCameraPosition.tilt)
                // new expected destination
                .target(ll)
                // north up or heading view
                .bearing((isHeading) ? bearing : 0f);
        newCameraUpdate = CameraUpdateFactory
                .newCameraPosition(cameraPositionBuilder.build());
    }

    return newCameraUpdate;
}

@Override
protected void onPostExecute(CameraUpdate result) {
    Log.d("test", Boolean.toString(isAnimating) + " onPostExecute");
    if (result != null) {
        nextCameraUpdate = result;
        // stop the currently playing animation
        // there is a new one ready to start
        if (isAnimating) {
            if (mMap != null) {
                mMap.stopAnimation();
            }
        }
        // start the next animation
        startAnimation();
        Log.d("test", Boolean.toString(isAnimating)  +" onPostExecuteComplete");
    }


}
}


// called when map animation has been canceled
@Override
public void onCancel() {
    Log.d("test", Boolean.toString(isAnimating)  +" oncancel");
    isAnimating = false;
}

@Override
public void onFinish() {
    Log.d("test", Boolean.toString(isAnimating)  +" onfinish");
    isAnimating = false;
    startAnimation();

    // call to start saved animation.
}

private void startAnimation() {
    Log.d("test", Boolean.toString(isAnimating)  +" startAnimation");
    if (action_track) {
        if (isAnimating) {
            return;
        }
        if (nextCameraUpdate == null) {
            return;
        }
        // abort if animating
        isAnimating = true;
        CameraUpdate animateCameraUpdate = nextCameraUpdate;
        nextCameraUpdate = null;
        mMap.animateCamera(animateCameraUpdate, working_interval, this);
        Log.d("test", Boolean.toString(isAnimating)  +" startanimateCamera");
    }
}