Horde_Image::circlePoint PHP Method

    public static function circlePoint($degrees, $diameter)
    {
        // Avoid problems with floats.
        $degrees += 0.0001;
        return array(cos(deg2rad($degrees)) * ($diameter / 2), sin(deg2rad($degrees)) * ($diameter / 2));
    }

 /**
  * Draws an arc.
  *
  * @param integer $x      The x coordinate of the centre.
  * @param integer $y      The y coordinate of the centre.
  * @param integer $r      The radius of the arc.
  * @param integer $start  The start angle of the arc.
  * @param integer $end    The end angle of the arc.
  * @param string  $color  The line color of the arc.
  * @param string  $fill   The fill color of the arc (defaults to none).
  */
 public function arc($x, $y, $r, $start, $end, $color = 'black', $fill = 'none')
 {
     // Split up arcs greater than 180 degrees into two pieces.
     $this->_postSrcOperations[] = "-stroke {$color} -fill {$fill}";
     $mid = round(($start + $end) / 2);
     $x = round($x);
     $y = round($y);
     $r = round($r);
     if ($mid > 90) {
         $this->_postSrcOperations[] = "-draw \"ellipse {$x},{$y} {$r},{$r} {$start},{$mid}\"";
         $this->_postSrcOperations[] = "-draw \"ellipse {$x},{$y} {$r},{$r} {$mid},{$end}\"";
     } else {
         $this->_postSrcOperations[] = "-draw \"ellipse {$x},{$y} {$r},{$r} {$start},{$end}\"";
     }
     // If filled, draw the outline.
     if (!empty($fill)) {
         list($x1, $y1) = Horde_Image::circlePoint($start, $r * 2);
         list($x2, $y2) = Horde_Image::circlePoint($mid, $r * 2);
         list($x3, $y3) = Horde_Image::circlePoint($end, $r * 2);
         $verts = array(array('x' => $x + round($x3), 'y' => $y + round($y3)), array('x' => $x, 'y' => $y), array('x' => $x + round($x1), 'y' => $y + round($y1)));
         if ($mid > 90) {
             $verts1 = array(array('x' => $x + round($x2), 'y' => $y + round($y2)), array('x' => $x, 'y' => $y), array('x' => $x + round($x1), 'y' => $y + round($y1)));
             $verts2 = array(array('x' => $x + round($x3), 'y' => $y + round($y3)), array('x' => $x, 'y' => $y), array('x' => $x + round($x2), 'y' => $y + round($y2)));
             $this->polygon($verts1, $fill, $fill);
             $this->polygon($verts2, $fill, $fill);
         } else {
             $this->polygon($verts, $fill, $fill);
         }
         $this->polyline($verts, $color);
         $this->_postSrcOperations[] = '-stroke none -fill none';
     }
 }