private void addScrollGapPath(int x,int y,int w,int h,boolean isAtLeft){
  final double hHalf=h / 2.0;
  final double wFull=isAtLeft ? w : 0;
  final double wHalfOff=isAtLeft ? w - hHalf : hHalf;
  path.quadTo(x + wHalfOff,y + h,x + wHalfOff,y + hHalf);
  path.quadTo(x + wHalfOff,y,x + wFull,y);
}

private void addScrollGapPath ( int x , int y , int w , int h , boolean isAtLeft ) { final double hHalf = h / 2.0 ; final double wFull = isAtLeft ? w : 0 ; final double wHalfOff = isAtLeft ? w - hHalf : hHalf ; path . quadTo ( x + wHalfOff , y + h , x + wHalfOff , y + hHalf ) ; path . quadTo ( x + wHalfOff , y , x + wFull , y ) ; }
adds a hemispherical section to the current path . this is used to create the gap in a scroll bar button or cap into which the scroll bar thumb will fit .
