PHP generates rounded corner image code

<?php
$image_file = $_GET[&#39;src&#39;];
$corner_radius = isset($_GET[&#39;radius&#39;]) ? $_GET[&#39;radius&#39;] : 20; // The default corner radius is set to 20px
$topleft = (isset($_GET[&#39;topleft&#39;]) and $_GET[&#39;topleft&#39;] == "no") ? false : true; // Top-left rounded corner is shown by default
$bottomleft = (isset($_GET[&#39;bottomleft&#39;]) and $_GET[&#39;bottomleft&#39;] == "no") ? false : true; // Bottom-left rounded corner is shown by default
$bottomright = (isset($_GET[&#39;bottomright&#39;]) and $_GET[&#39;bottomright&#39;] == "no") ? false : true; // Bottom-right rounded corner is shown by default
$topright = (isset($_GET[&#39;topright&#39;]) and $_GET[&#39;topright&#39;] == "no") ? false : true; // Top-right rounded corner is shown by default
$imagetype=strtolower($_GET[&#39;imagetype&#39;]);
$backcolor=$_GET[&#39;backcolor&#39;];
$endsize=$corner_radius;
$startsize=$endsize*3-1;
$arcsize=$startsize*2+1;
   
if (($imagetype==&#39;jpeg&#39;) or ($imagetype==&#39;jpg&#39;)) {
$image = imagecreatefromjpeg($image_file);
} else {
if (($imagetype==&#39;GIF&#39;) or ($imagetype==&#39;gif&#39;)) {
$image = imagecreatefromgif($image_file);
} else {
$image = imagecreatefrompng($image_file);
}
}
   
   
$size = getimagesize($image_file);
// Top-left corner
$background = imagecreatetruecolor($size[0],$size[1]);
imagecopymerge($background, $image, 0, 0, 0, 0, $size[0], $size[1], 100);
$startx=$size[0]*2-1;
$starty=$size[1]*2-1;
$im_temp = imagecreatetruecolor($startx,$starty);
imagecopyresampled($im_temp, $background, 0, 0, 0, 0, $startx, $starty, $size[0], $size[1]);
$bg = imagecolorallocate($im_temp, hexdec(substr($backcolor,0,2)),hexdec(substr($backcolor,2,2)),hexdec(substr($backcolor,4,2)));
$fg = imagecolorallocate($im_temp, hexdec(substr($forecolor,0,2)),hexdec(substr($forecolor,2,2)),hexdec(substr($forecolor,4,2)));
   
if ($topleft == true) {
imagearc($im_temp, $startsize, $startsize, $arcsize, $arcsize, 180,270,$bg);
imagefilltoborder($im_temp,0,0,$bg,$bg);
}
   
// Bottom-left corner
if ($bottomleft == true) {
imagearc($im_temp, $startsize, $starty-$startsize,$arcsize, $arcsize, 90,180,$bg);
imagefilltoborder($im_temp,0,$starty,$bg,$bg);
}
   
// Bottom-right corner
if ($bottomright == true) {
imagearc($im_temp, $startx-$startsize, $starty-$startsize,$arcsize, $arcsize, 0,90,$bg);
imagefilltoborder($im_temp,$startx,$starty,$bg,$bg);
}
   
// Top-right corner
if ($topright == true) {
imagearc($im_temp, $startx-$startsize, $startsize,$arcsize, $arcsize, 270,360,$bg);
imagefilltoborder($im_temp,$startx,0,$bg,$bg);
}
   
   
$newimage = imagecreatetruecolor($size[0],$size[1]);
imagecopyresampled($image, $im_temp, 0, 0, 0, 0, $size[0],$size[1],$startx, $starty);
   
// Output final image
header("Content-type: image/png");
imagepng($image);
imagedestroy($image);
imagedestroy($background);
imagedestroy($im_temp);
?>