android maps: how to determine map center after a drag has been completed
Is there a way through the android maps API, where I can detect the map center after pan animation has completed开发者_如何学Python? I want to use this information to load markers from a server dynamically. Thanks BD
I also have been looking for a "did end drag" solution that detects the map center at the moment exactly after the map ended moving. I haven't found it, so I've made this simple implementation that did work fine:
private class MyMapView extends MapView {
private GeoPoint lastMapCenter;
private boolean isTouchEnded;
private boolean isFirstComputeScroll;
public MyMapView(Context context, String apiKey) {
super(context, apiKey);
this.lastMapCenter = new GeoPoint(0, 0);
this.isTouchEnded = false;
this.isFirstComputeScroll = true;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_DOWN)
this.isTouchEnded = false;
else if (event.getAction() == MotionEvent.ACTION_UP)
this.isTouchEnded = true;
else if (event.getAction() == MotionEvent.ACTION_MOVE)
this.isFirstComputeScroll = true;
return super.onTouchEvent(event);
}
@Override
public void computeScroll() {
super.computeScroll();
if (this.isTouchEnded &&
this.lastMapCenter.equals(this.getMapCenter()) &&
this.isFirstComputeScroll) {
// here you use this.getMapCenter() (e.g. call onEndDrag method)
this.isFirstComputeScroll = false;
}
else
this.lastMapCenter = this.getMapCenter();
}
}
That's it, I hope it helps! o/
Are you using a MapActivity
? Here's the code I've used:
MapView mapView = (MapView)findViewById(R.id.map);
Projection projection = mapView.getProjection();
int y = mapView.getHeight() / 2;
int x = mapView.getWidth() / 2;
GeoPoint geoPoint = projection.fromPixels(x, y);
double centerLatitude = (double)geoPoint.getLatitudeE6() / (double)1E6;
double centerLongitude = (double)geoPoint.getLongitudeE6() / (double)1E6;
You do need to add code similar to this also:
@Override
public boolean dispatchTouchEvent(MotionEvent event)
{
boolean result = super.dispatchTouchEvent(event);
if (event.getAction() == MotionEvent.ACTION_UP)
reload_map_data(); /// call the first block of code here
return result;
}
Since August 2016 Maps for Android is capable of detecting events such as onCameraMoveStarted
(and the reasons for the move, e.g., REASON_GESTURE
, REASON_DEVELOPER_ANIMATION
.
The following code (mostly taken from the docs) gives an idea of what you can achieve:
public class MyCameraActivity extends FragmentActivity implements
OnCameraMoveStartedListener,
OnCameraMoveListener,
OnCameraMoveCanceledListener,
OnCameraIdleListener,
OnMapReadyCallback {
private GoogleMap mMap;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_my_camera);
SupportMapFragment mapFragment =
(SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
}
@Override
public void onMapReady(GoogleMap map) {
mMap = map;
mMap.setOnCameraIdleListener(this);
mMap.setOnCameraMoveStartedListener(this);
mMap.setOnCameraMoveListener(this);
mMap.setOnCameraMoveCanceledListener(this);
// Show Sydney on the map.
mMap.moveCamera(CameraUpdateFactory
.newLatLngZoom(new LatLng(-33.87365, 151.20689), 10));
}
@Override
public void onCameraMoveStarted(int reason) {
if (reason == OnCameraMoveStartedListener.REASON_GESTURE) {
Toast.makeText(this, "The user gestured on the map.",
Toast.LENGTH_SHORT).show();
} else if (reason == OnCameraMoveStartedListener
.REASON_API_ANIMATION) {
Toast.makeText(this, "The user tapped something on the map.",
Toast.LENGTH_SHORT).show();
} else if (reason == OnCameraMoveStartedListener
.REASON_DEVELOPER_ANIMATION) {
Toast.makeText(this, "The app moved the camera.",
Toast.LENGTH_SHORT).show();
}
}
@Override
public void onCameraMove() {
Toast.makeText(this, "The camera is moving.",
Toast.LENGTH_SHORT).show();
}
@Override
public void onCameraMoveCanceled() {
Toast.makeText(this, "Camera movement canceled.",
Toast.LENGTH_SHORT).show();
}
@Override
public void onCameraIdle() {
Toast.makeText(this, "The camera has stopped moving.",
Toast.LENGTH_SHORT).show();
// Here you get the camera center
GeoPoint geoPoint = projection.fromPixels(mMap.getHeight() / 2, mMap.getWidth() / 2);
double centerLat = (double)geoPoint.getLatitudeE6() / (double)1E6;
double centerLng = (double)geoPoint.getLongitudeE6() / (double)1E6;
}
}
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