Hi,
I am trying to import a PNG image from disk, place it on top of a
transparant image created in GD and output it to the browser. In the case of
a low opacity setting, I would expect to see the background colour from the
HTML page.
If I set the opacity to 0, everything works - I end up with a transparant
image.
However, if I set it for any value >0 (even 1) instead of a
very-faint-image the whole thing goes black. As the opacity level goes up
from 0, the amount of black reduces and the amount of imported image
increases - but this is not what I want.
I am using this code:
<?php
$src = imagecreatefrompng('test.png');
$img_width = imagesx($src);
$img_height = imagesy($src);
// Create trans image
$dest = imagecreatetruecolor($img_width, $img_height);
//imagesavealpha($dest, true); // This has no effect it appears
$trans_colour = imagecolorallocatealpha($dest, 0, 255, 0, 128);
// Make the background transparent
imagecolortransparent($dest, $trans_colour);
//imagefill($dest, 0, 0, $trans_colour); // This does not work
// Merge src on top of dest, with opacity of 1 in this case
imagecopymerge($dest, $src, 0, 0, 0, 0, $img_width, $img_height, 1);
// Output and free from memory
header('Content-Type: image/png');
imagepng($dest);
?>
The images that this outputs, at opacity levels 0,1 and 80 on a red and
green background (screenshots of a HTML page) can be downloaded from
http://www.box.net/shared/h9zn4tjgro
Any help appreciated!
Cheers,
Alex
