Improve my php image resizer to support alpha png and transparent GIFs
- by David
Hi,
I use this function to resize images but i end up with ugly creepy image with a black background if it's a transparent GIF or PNG with alpha, however it works perfectly for jpg and normal png.
function cropImage($nw, $nh, $source, $stype, $dest) {
$size = getimagesize($source);
$w = $size[0];
$h = $size[1];
switch($stype) {
case 'gif':
$simg = imagecreatefromgif($source);
break;
case 'jpg':
$simg = imagecreatefromjpeg($source);
break;
case 'png':
$simg = imagecreatefrompng($source);
break;
}
$dimg = imagecreatetruecolor($nw, $nh);
switch ($stype)
{
case "png":
imagealphablending( $dimg, false );
imagesavealpha( $dimg, true );
$transparent = imagecolorallocatealpha($dimg, 255, 255, 255, 127);
imagefilledrectangle($dimg, 0, 0, $nw, $nh, $transparent);
break;
case "gif":
// integer representation of the color black (rgb: 0,0,0)
$background = imagecolorallocate($simg, 0, 0, 0);
// removing the black from the placeholder
imagecolortransparent($simg, $background);
break;
}
$wm = $w/$nw;
$hm = $h/$nh;
$h_height = $nh/2;
$w_height = $nw/2;
if($w> $h) {
$adjusted_width = $w / $hm;
$half_width = $adjusted_width / 2;
$int_width = $half_width - $w_height;
imagecopyresampled($dimg,$simg,-$int_width,0,0,0,$adjusted_width,$nh,$w,$h);
} elseif(($w <$h) || ($w == $h)) {
$adjusted_height = $h / $wm;
$half_height = $adjusted_height / 2;
$int_height = $half_height - $h_height;
imagecopyresampled($dimg,$simg,0,-$int_height,0,0,$nw,$adjusted_height,$w,$h);
} else {
imagecopyresampled($dimg,$simg,0,0,0,0,$nw,$nh,$w,$h);
}
imagejpeg($dimg,$dest,100);
}
I use php 5.3.2 and the GD library bundled (2.0.34 compatible)
Thanks
