android google map marker placing

Question

In my Android application I need to place marker at exact position on map. I pin a marker on map with 51.507351, -0.127758 (London) location. I used the following code to do the work.

googleMap.addMarker(new MarkerOptions().position(
        new LatLng(51.507351, -0.127758)).icon(
        BitmapDescriptorFactory.fromBitmap(BitmapFactory
                .decodeResource(getResources(),
                        R.drawable.q_icon))));
googleMap.moveCamera(CameraUpdateFactory.newLatLngZoom(
        new LatLng(51.507351, -0.127758), 20));

And this my marker drawable image:

Now my problem is, the "Q" symbol is placed at the location of 51.507351, -0.127758. I need to place marker at the position where bottom arrow starts.

Please see the picture so that you can understand my question.

How can I do this? please help me.

Answer 1

The logic behind how the markers are anchored is something like this for a 4px-by-2px image:

        0,0      0.5,0.0        1,0
        *-----+-----+-----+-----*
        |     |     |     |     |
        |     |     |     |     |
  0,0.5 +-----+-----+-----+-----+ 1,0.5
        |     |     |   X |     |           (U, V) = (0.7, 0.6)
        |     |     |     |     |
        *-----+-----+-----+-----*
        0,1      0.5,1.0        1,1

Also take into consideration that based on your bitmap resource, it could be positioned a little different than you would expect, because they actually approximate to the nearest snap position. So in the example above, your anchor points will snap to this position:

 *-----+-----+-----+-----*
 |     |     |     |     |
 |     |     |     |     |
 +-----+-----+-----X-----+   (X, Y) = (3, 1)
 |     |     |     |     |
 |     |     |     |     |
 *-----+-----+-----+-----*

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