GD and transparent background

PHP
1

I have this code:

header("Content-type: image/png");

$string = "My text";

$font  = 2;
$width  = imagefontwidth($font) * strlen($string);
$height = imagefontheight($font);

$image = imagecreatetruecolor ($width,$height);
$white = imagecolorallocate ($image,255,255,255);
$black = imagecolorallocate ($image,0,0,0);
imagefill($image,0,0,$white);

imagestring ($image,$font,0,0,$string,$black);

imagepng ($image);
imagedestroy($image);

How can I simply make sure the background is transparent?

2

Try something like this:

header("Content-type: image/png");

$string = "My text";

$font  = 2;
$width  = imagefontwidth($font) * strlen($string);
$height = imagefontheight($font);

$image = imagecreatetruecolor ($width,$height);
imagealphablending($image , false);
imagesavealpha($image , true);

$transparent = imagecolorallocatealpha($image , 255, 255, 255, 127);
$white = imagecolorallocate ($image,255,255,255);
$black = imagecolorallocate ($image,0,0,0);
imagefill($image,0,0,$transparent);

imagestring ($image,$font,0,0,$string,$black);

imagepng ($image);
imagedestroy($image);
3

Perfect! Thanks