OpenStreetMap add marker to Nutiteq MapView with custom Xfermode

I need to put some markers on top of a Nutiteq MapView. In order to create these markers I create a bitmap with a semi-transparent circle.

int size = (int)(30*mDisplayMetrics.density);
Bitmap androidMarkerBitmap = Bitmap.createBitmap(size, size, Bitmap.Config.ARGB_8888);
Paint paint = new Paint();
paint.setColor(Color.argb(150, 255, 0, 0));

Canvas canvas = new Canvas(androidMarkerBitmap);
canvas.drawCircle(size / 2, size / 2, size / 2, paint);
com.nutiteq.graphics.Bitmap markerBitmap = BitmapUtils.createBitmapFromAndroidBitmap(androidMarkerBitmap);
androidMarkerBitmap.recycle();

Each marker has the same bitmap. The problem is the transparency of the bitmap (as you can see alpha is not 0). When I add many markers all the bitmaps are simply ADDED one over the another... The problem is that I do not want the "add" effect for transparency, but instead I need to obtain the "darken" one.

_{(source: csdn.net)}

Is there a way to change the default Xfermode used when mapView draws markers on it?

No, there is no such option in Nutiteq SDK. The effect you describe would require rendering markers to a separate surface (with 'darken' effect) and then layering the rendered surface (with markers) atop of other layers. Such functionality is pretty expensive and is not implemented in the SDK.