(PHP 4 >= 4.3.2, PHP 5)
imagesavealpha — Set the flag to save full alpha channel information (as opposed to single-color transparency) when saving PNG images
$image
, bool $saveflag
)imagesavealpha() sets the flag to attempt to save full alpha channel information (as opposed to single-color transparency) when saving PNG images.
You have to unset alphablending (imagealphablending($im, false)), to use it.
Alpha channel is not supported by all browsers, if you have problem with your browser, try to load your script with an alpha channel compliant browser, e.g. latest Mozilla.
imageUna risorsa immagine, restituita da una delle funzioni di creazione immagine, come imagecreatetruecolor().
saveflag
Whether to save the alpha channel or not. Default to FALSE.
Restituisce TRUE in caso di successo, FALSE in caso di fallimento.
Example #1 imagesavealpha() example
<?php
// Load a png image with alpha channels
$png = imagecreatefrompng('./alphachannel_example.png');
// Do required operations
// Turn off alpha blending and set alpha flag
imagealphablending($png, false);
imagesavealpha($png, true);
// Output image to browser
header('Content-Type: image/png');
imagepng($png);
imagedestroy($png);
?>
Nota: Questa funzione necessita di GD 2.0.1 o successivi (raccomandato 2.0.28 o successivi).