Android setFocusArea and Auto Focus

Android setFocusArea and Auto Focus

I've been battling with this feature for couple of days now...
It seems, that camera is ignoring(?) focus areas that I've defined. Here
is snippets of the code:
Focusing:
protected void focusOnTouch(MotionEvent event) {
if (camera != null) {
Rect rect = calculateFocusArea(event.getX(), event.getY());
Parameters parameters = camera.getParameters();
parameters.setFocusMode(Parameters.FOCUS_MODE_AUTO);
parameters.setFocusAreas(Lists.newArrayList(new Camera.Area(rect,
500)));
camera.setParameters(parameters);
camera.autoFocus(this);
}
}
Focus area calculation:
private Rect calculateFocusArea(float x, float y) {
int left = clamp(Float.valueOf((x / getSurfaceView().getWidth()) *
2000 - 1000).intValue(), focusAreaSize);
int top = clamp(Float.valueOf((y / getSurfaceView().getHeight()) *
2000 - 1000).intValue(), focusAreaSize);
return new Rect(left, top, left + focusAreaSize, top + focusAreaSize);
}
Couple of log events from Camera.AutoFocusCallback#onAutoFocus
Log.d(TAG, String.format("Auto focus success=%s. Focus mode: '%s'. Focused
on: %s", focused, camera.getParameters().getFocusMode(),
camera.getParameters().getFocusAreas().get(0).rect.toString()));
08-27 11:19:42.240: DEBUG/MyCameraActivity(26268): Auto focus
success=true. Focus mode: 'auto'. Focused on: Rect(-109, 643 - -13, 739)
08-27 11:19:55.514: DEBUG/MyCameraActivity(26268): Auto focus
success=true. Focus mode: 'auto'. Focused on: Rect(20, 457 - 116, 553)
08-27 11:19:58.037: DEBUG/MyCameraActivity(26268): Auto focus
success=true. Focus mode: 'auto'. Focused on: Rect(-159, 536 - -63, 632)
08-27 11:20:00.129: DEBUG/MyCameraActivity(26268): Auto focus
success=true. Focus mode: 'auto'. Focused on: Rect(-28, 577 - 68, 673)
Visually it looks like focus succeeds on logged area, but the suddenly it
loses focus and focus on center (0, 0), or what takes bigger part of
SurfaceView is obtained.
focusAreaSize used in calculation is about 210px (96dp). Testing on HTC
One where Camera.getParameters().getMaxNumFocusAreas() is 1.
Initial focus mode (before first tap) is set to
FOCUS_MODE_CONTINUOUS_PICTURE.
Am I doing something wrong here? Tinkering with Camera.Area rectangle size
or weight doesn't show any noticeable effect.