How do i get a transparent background after rotaing a png image with php?

Question

So I have png image and I rotate it but i get a black background.. or if i do the color code ofr white i get white.. I tried doing this..

$trans = imagecolorallocatealpha(image, 0, 0, 0, 127);
imagerotate($image, $degree, $trans)

i have also tried..

$trans = imagecolorallocatealpha($image, 255, 255, 255, 127);

Can someone help me out?

here is my code.. if i change allocatealpha to 0, 0, 255, 0 then it goes blue. but with 0, 0, 0, 127 its still black.

function rotate($degrees) {
$image = $this->image;
imagealphablending($image, false);
$color = imagecolorallocatealpha($image, 0, 0, 0, 127);
imagefill($this->image, 0, 0, $color);
$rotate = imagerotate($image, $degrees, $color);
imagesavealpha($image, TRUE);
$this->image = $rotate;

Answer 1

$destimg = imagecreatefromjpeg("image.png");
$transColor = imagecolorallocatealpha($destimg, 255, 255, 255, 127);
$rotatedImage = imagerotate($destimg, 200, $transColor);
imagesavealpha($rotatedImage, true);
imagepng($rotatedImage,"rotated.png");