Each event record has following attributes to represent the detected face coordinates.
- leftAtStart
- topAtStart
- widthAtStart
- heightAtSart
- left
- top
- width
- height
These values have range of [0..1], normalized to the fame width and height.
leftAtStart, topAtStart, widthAtStart, heightAtStart indicate the value when the face was detected at first.
left, top, width, height indicate the value of current face position.
