PNG Transparency

Hi,

I am using the following function which works fine however when uploading PNG's that are transparent it does not keep the transparancy and makes it black. What do i need to change on the below to keep the transparency?

 function uploadimage($value, $alwidth)
{
   
   $file_type = $value['type'];
    $file_name = $value['name'];
    $file_size = $value['size'];
    $file_tmp = $value['tmp_name'];

//check file extension
       $ext = strrchr($file_name,'.');
       $ext = strtolower($ext);
       if (($extlimit == "yes") && (!in_array($ext,$limitedext))) {
          echo "Wrong file extension.  <br>--<a href=\"$_SERVER[PHP_SELF]\">back</a>";
          exit();
       }

    //get the file extension.
    $getExt = explode ('.', $file_name);
    $file_ext = $getExt[count($getExt)-1];

    //create a random file name
    $rand_name = md5(time());
    $rand_name= rand(0,999999999);
    //get the new width variable.
    list($ewidth, $eheight) = getimagesize($file_tmp);
    if ($ewidth < 250){
        $ThumbWidth = $ewidth;
    }else{
        $ThumbWidth = 250;
    }
    if ($alwidth == ''){
        
        if ($ewidth < 600){
            $ImgWidth = ($ewidth + 40);
        }else{
            $ImgWidth = 640;
        }
        
    }else{
        $ImgWidth = $alwidth;
    }
    
    if ($ewidth < 420){
        $medWidth = $ewidth;
    }else{
        $medWidth = 420;
    }

    //keep image type
    if($file_size){
        if($file_type == "image/pjpeg" || $file_type == "image/jpeg"){
            $new_img = imagecreatefromjpeg($file_tmp);
        }elseif($file_type == "image/x-png" || $file_type == "image/png"){
            $new_img = imagecreatefrompng($file_tmp);
        }elseif($file_type == "image/gif"){
            $new_img = imagecreatefromgif($file_tmp);
        }
        //list width and height and keep height ratio.
        list($width, $height) = getimagesize($file_tmp);
                
        $bigger = ($width >= $height) ? $width : $height; 
    
        $imgratio = $bigger / $ThumbWidth;
        $newwidth = intval($width / $imgratio);
        $newheight = intval($height / $imgratio);
        
        $imgratio = $bigger / $ImgWidth;
        $newwidth2 = intval($width / $imgratio);
        $newheight2 = intval($height / $imgratio);
        
        $imgratio = $bigger / $medWidth;
        $newwidth3 = intval($width / $imgratio);
        $newheight3 = intval($height / $imgratio);
        
        
        $resized_img = imagecreatetruecolor($newwidth, $newheight);
        imagecopyresampled($resized_img, $new_img, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
        
        $resized_img2 = imagecreatetruecolor($newwidth2, $newheight2);
        imagecopyresampled($resized_img2, $new_img, 0, 0, 0, 0, $newwidth2, $newheight2, $width, $height);
        
        $resized_img3 = imagecreatetruecolor($newwidth3, $newheight3);
        imagecopyresampled($resized_img3, $new_img, 0, 0, 0, 0, $newwidth3, $newheight3, $width, $height);
        
        imagejpeg($resized_img, "imgtemp/thumbs/".$rand_name.".".$file_ext,100);  
        imagejpeg($resized_img2, "imgtemp/big/".$rand_name.".".$file_ext,100);
        imagejpeg($resized_img3, "imgtemp/med/".$rand_name.".".$file_ext,100);

        //save images
        ftpupload($rand_name.".".$file_ext, "imgtemp/thumbs/".$rand_name.".".$file_ext, "/httpdocs/uploads/images/thumbs/");
        ftpupload($rand_name.".".$file_ext, "imgtemp/big/".$rand_name.".".$file_ext, "/httpdocs/uploads/images/big/");
        ftpupload($rand_name.".".$file_ext, "imgtemp/med/".$rand_name.".".$file_ext, "/httpdocs/uploads/images/med/");
        
        unlink("imgtemp/big/".$rand_name.".".$file_ext);
        unlink("imgtemp/thumbs/".$rand_name.".".$file_ext);
        unlink("imgtemp/med/".$rand_name.".".$file_ext);
        
        imagedestroy($resized_img);
        imagedestroy($resized_img2);
        imagedestroy($resized_img3);
        imagedestroy($new_img);

    }   
    $value = $rand_name.".".$file_ext;
    return $value;
}

PHP:

Thanks in advance.
Adam

 

Hello, Google 'keep png transparency when uploading' and the first result from Stack Overflow looks promising. ​

 

You need more than imagecreatefrompng() if you want to preserve transparency. Check this out.

 

or you have to allocate the 'color' (normal black) to transparant.

http://php.net/manual/en/function.imagecolortransparent.php