(PECL haru >= 0.0.1)
HaruPage::arc — Append an arc to the current path
$x
   , float $y
   , float $ray
   , float $ang1
   , float $ang2
   )Appends an arc to the current path.
x
     Horizontal coordinate of the center.
y
     Vertical coordinate of the center.
ray
     The ray of the arc.
ang1
     The angle of the beginning.
ang2
     
       The angle of the end. Must be greater than ang1.
      
   Returns TRUE on success.
  
发生错误时抛出 HaruException 异常。