question: 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 ) ; }
target:  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.