Redimensionnement de la transparence PNG avec SimpleImage.php Class

Je suis en utilisant une version modifiée de la SimpleImage.php catégorie: http://www.white-hat-web-design.co.uk/articles/php-image-resizing.php

Les modifications que j'ai trouvé sur phpfreaks (http://www.phpfreaks.com/forums/index.php?topic=301811.0), mais quand je l'utilise, le png est redimensionnée, mais la transparence est noir.

Je fais l'appel comme:

 $max_width = 200; //set a max width
 $max_height = 150; //set a max height
 if($imgW > $imgH){ //width is greater
      //resize to width up to max
      if($imgW > $max_width) $image->resizeToWidth($max_width);
 }
 else { //height is greater
      //resize to height up to max
      if($imgH > $max_height) $image->resizeToHeight($max_height);
 }

 $image->save($_SERVER['DOCUMENT_ROOT']."/path/" . $new_filename);

Je ne suis pas sûr de ce qu'il manque. Toute aide est appréciée...

class SimpleImage {
var $image;
var $image_type;
function load($filename) {
$image_info = getimagesize($filename);
$this->image_type = $image_info[2];
if( $this->image_type == IMAGETYPE_JPEG ) {
$this->image = imagecreatefromjpeg($filename);
} elseif( $this->image_type == IMAGETYPE_GIF ) {
$this->image = imagecreatefromgif($filename);
} elseif( $this->image_type == IMAGETYPE_PNG ) {
$this->image = imagecreatefrompng($filename);
}
}
function save($filename, $image_type=IMAGETYPE_JPEG, $compression=75, $permissions=null) {
if( $image_type == IMAGETYPE_JPEG ) {
imagejpeg($this->image,$filename,$compression);
} elseif( $image_type == IMAGETYPE_GIF ) {
imagegif($this->image,$filename);
} elseif( $image_type == IMAGETYPE_PNG ) {
imagepng($this->image,$filename);
}
if( $permissions != null) {
chmod($filename,$permissions);
}
}
function output($image_type=IMAGETYPE_JPEG) {
if( $image_type == IMAGETYPE_JPEG ) {
imagejpeg($this->image);
} elseif( $image_type == IMAGETYPE_GIF ) {
imagegif($this->image);
} elseif( $image_type == IMAGETYPE_PNG ) {
imageAlphaBlending($this->image, true);
imageSaveAlpha($this->image, true);
imagepng($this->image);
}   
}
function getWidth() {
return imagesx($this->image);
}
function getHeight() {
return imagesy($this->image);
}
function resizeToHeight($height) {
$ratio = $height / $this->getHeight();
$width = $this->getWidth() * $ratio;
$this->resize($width,$height);
}
function resizeToWidth($width) {
$ratio = $width / $this->getWidth();
$height = $this->getheight() * $ratio;
$this->resize($width,$height);
}
function scale($scale) {
$width = $this->getWidth() * $scale/100;
$height = $this->getheight() * $scale/100;
$this->resize($width,$height);
}
function resize($width,$height) {
//ADDED CODE IS HERE - NOT SURE WHY IT DOESN'T WORK FOR PNG
//Setup new image
$new_image = imagecreatetruecolor($width, $height);
//These parameters are required for handling PNG files.
imagealphablending($new_image, false);
imagesavealpha($new_image,true);
$transparent = imagecolorallocatealpha($new_image, 255, 255, 255, 127);
imagefilledrectangle($new_image, 0, 0, $width, $height, $transparent);
//Resize image
imagecopyresampled($new_image, $this->image, 0, 0, 0, 0, $width, $height, $this->getWidth(), $this->getHeight());
$this->image = $new_image;
}
}

source d'informationauteur Don