Android 9PNG images The meaning of each edge

Number 1th black bar position to the right covers the area when the picture is stretched vertically.

The area covered by the 2nd black bar position indicates that the area is stretched only when the picture is stretched horizontally

Number 3rd black bar position to the left covers the area where the picture is displayed vertically (mainly in the text area on the phone)

No. 4th Black bar position up-covered area indicates the area where the picture is displayed horizontally (mostly text area on the phone)

Android 9PNG images The meaning of each edge