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android – How to handle onTouch event for map in Google Map API v2?

Posted by: admin April 23, 2020 Leave a comment

Questions:

GoogleMap by default doesn’t provide event for map drag start and drag stop. I have already reported that problem here.

I want to make custom handler that will use plain onTouch event and combine it with setOnCameraChangeListener.

However i failed to find how I can access onTouch event of GoogleMap object. It doesn’t provide such callback.

I wonder how can i handle onTouch event for map in Google Map API v2?

How to&Answers:

Here is a possible workaround for determining drag start and drag end events:

You have to extend SupportMapFragment or MapFragment. In onCreateView() you have to wrap your MapView in a customized FrameLayout (in example below it is the class TouchableWrapper), in which you intercepts touch events and recognizes whether the map is tapped or not. If your onCameraChange gets called, just check whether the map view is pressed or not (in example below this is the variable mMapIsTouched).

Example code:

UPDATE 1:

  • return original created view in getView()
  • use dispatchTouchEvent() instead of onInterceptTouchEvent()

Customized FrameLayout:

private class TouchableWrapper extends FrameLayout {
    @Override
    public boolean dispatchTouchEvent(MotionEvent ev) {
    switch (ev.getAction()) {
        case MotionEvent.ACTION_DOWN:
        mMapIsTouched = true;
        break;

    case MotionEvent.ACTION_UP:
        mMapIsTouched = false;
        break;
        }

        return super.dispatchTouchEvent(ev);
    }
    }

In your customized MapFragment:

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle savedInstanceState) {
    mOriginalContentView = super.onCreateView(inflater, parent, savedInstanceState);

    mTouchView = new TouchableWrapper(getActivity());
    mTouchView.addView(mOriginalContentView);

    return mTouchView;
}

@Override
public View getView() {
    return mOriginalContentView;
}

In your camera change callback method:

private final OnCameraChangeListener mOnCameraChangeListener = new OnCameraChangeListener() {
    @Override
    public void onCameraChange(CameraPosition cameraPosition) {
        if (!mMapIsTouched) {
            refreshClustering(false);
        }
    }
};

Answer:

There is a simpler way to do this, handle your cases on onCameraMoveStarted listener like this

Below the code snippet

@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();
    }
}