question: private static void addQuarterArc ( Path2D . Float path , float x1 , float y1 , float x2 , float y2 , float curvature , boolean verticalStart ) { boolean down = y1 < y2 ; boolean left = x1 > x2 ; float cx1 = 0 ; float cy1 = 0 ; float cx2 = 0 ; float cy2 = 0 ; if ( verticalStart ) { cx1 = x1 ; cy2 = y2 ; if ( left ) { cx2 = x1 - curvature ; } else { cx2 = x1 + curvature ; } if ( down ) { cy1 = y2 - curvature ; } else { cy1 = y2 + curvature ; } } else { cx2 = x2 ; cy1 = y1 ; if ( left ) { cx1 = x2 + curvature ; } else { cx1 = x2 - curvature ; } if ( down ) { cy2 = y1 + curvature ; } else { cy2 = y1 - curvature ; } } path . curveTo ( cx1 , cy1 , cx2 , cy2 , x2 , y2 ) ; }
target:  Add a quarter circular path to a given path object, starting from (x1, y1) to (x2, y2).