Handling touch events in SurfaceView over Maps API v2

Question

I'm having issues in creating event handler that will be triggered while user moves the map around. There is a OnCameraChangeListener, but it is triggered after map moving stops.

I have created SurfaceView over Maps, and now I have no idea how to handle onScroll event from OnGestureListener.

Here is the sample code:

SurfaceView sv = new SView();
sv.setZOrderOnTop(true);
mapView.addView(sv);

...

public class SView extends SurfaceView implements Runnable, android.view.GestureDetector.OnGestureListener {
...
@Override
public boolean onTouchEvent(MotionEvent event) {
    //this worked in Overlay in Maps API v1
    if(gestureDetector.onTouchEvent(event)) {
        return true;
    }
    return false;
}
...

@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
    Log.i("test","onScroll");
    return false;
}

...
}

If I set return true in onTouchEvent, onScroll is called but than I can't move the Map (which is obvious, the event is consumed), and I don't know how to dispatch event down to Map object.

Anyone knows how to update SurfaceView while Map is moved?

Answer 1

I have implemented some other solution to solve this problem. What I did - is I placed my GoogleMap inside custom RelativeLayout. After that onInterceptTouchEvent callback works like a charm and underlying map receives touch events as expected

here is my xml:

<com.my.package.name.map.MapRelativeLayout
    android:id="@+id/map_root_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

     <fragment
        android:id="@+id/map"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        class="com.google.android.gms.maps.SupportMapFragment"/>

</com.my.package.name.map.MapRelativeLayout>

And custom relative layout:

package com.my.package.name.map;

import android.content.Context;
import android.util.AttributeSet;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.widget.RelativeLayout;

public class MapRelativeLayout extends RelativeLayout
{
    private GestureDetector gestureDetector;

    public MapRelativeLayout(Context context, AttributeSet attrs)
    {
        super(context, attrs);
        gestureDetector = new GestureDetector(context, new GestureListener());
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev)
    {
        gestureDetector.onTouchEvent(ev);
        return false;
    }

    private class GestureListener extends GestureDetector.SimpleOnGestureListener {

        @Override
        public boolean onDown(MotionEvent e) {
            return true;
        }
        @Override
        public boolean onDoubleTap(MotionEvent e) {
            return false;
        }

        @Override
        public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
                float velocityY)
        {
            return false;
        }

        @Override
        public boolean onScroll(MotionEvent e1, MotionEvent e2,
                float distanceX, float distanceY)
        {
            //do whatever you want here
            return false;
        }
    }
}

Answer 2

From: Android ListView: overriding causes scrolling do not executed

Have you tried calling super.onTouchEvent(event) in your onTouchEvent method?

Edit - I think you want to return false as well in your onScroll method.

Then your onTouchEvent method should be:

@Override
public boolean onTouchEvent(MotionEvent event) {
    if (gestureDetector.onTouchEvent(event)) {
        return true;
    }
    return super.onTouchEvent(event);
}

Other possible helpful links:

• Android: how to tell if a view is scrolling
• Adding GestureOverlayView to my SurfaceView class, how to add to view hierarchy?
• Android onFling not responding
• OnGestureListener onDown method never gets called
• Overriding onTouchEvent competing with ScrollView