uploading png images with transparent background using php and keeping the background transparent

Question

I have a php page which takes a user image and uploads it to my webserver.

I have just noticed that if I have a png with a transparent background, and upload it, the background is changed to white.

For example I create a new image in photoshop with a transparent background and then add a coloured circle to the page. I save the image as a png and uplod to the server via ftp then the image is shown as a circle on the webpage as the background is transparent.

If I upload the image using php with a file input box the image is changed to white.

I have tried to use imagealphablending,imagecolorallocatealpha,imagefill and imagesavealpha to retain the transparent background but it just changes the bg to black.

any clues?

heres my php code

        <?php
    $path = "../userfiles/orig/";
    $userpath="../".$_REQUEST['userpath']."/";

    function getExtension($str) {
        $i = strrpos($str,".");
        if (!$i) { return ""; } 
        $l = strlen($str) - $i;
        $ext = substr($str,$i+1,$l);
        return $ext;
    }

    $valid_formats = array("jpg", "png", "gif", "bmp","jpeg","PNG","JPG","JPEG","GIF","BMP");

    if(isset($_POST) and $_SERVER['REQUEST_METHOD'] == "POST"){
        $name = $_FILES['photoimg']['name'];
        $size = $_FILES['photoimg']['size'];

        if(strlen($name)){
                 $ext = getExtension($name);

                if(in_array($ext,$valid_formats)){

                    if($size<(2048*2048)){
                        $time1=time();
                        $actual_image_name =$time1."_".str_replace(" ", "_", $name);
                        $tmp = $_FILES['photoimg']['tmp_name'];

                        if(move_uploaded_file($tmp, $path.$actual_image_name)){                                     
                                     $image=$actual_image_name;                     
                                     /*--------resize image-----------*/
                                     $size = 320; // the imageheight
                                     $filedir = '../userfiles/orig/'; // the directory for the original image
                                     $thumbdir = $userpath; // the directory for the resized image
                                     $prefix = $time1.'_'; // the prefix to be added to the original name
                                     $maxfile = '20000000'; 
                                     $mode = '0666';
                                     $userfile_name =str_replace(" ", "", $_FILES['photoimg']['name']);
                                     $userfile_tmp = str_replace(" ", "", $_FILES['photoimg']['tmp_name']);
                                     $userfile_size =$_FILES['photoimg']['size'];
                                     $userfile_type = $_FILES['photoimg']['type'];

                                     if (isset($_FILES['photoimg']['name'])){
                                         $prod_img = $filedir.$actual_image_name;
                                         $prod_img_thumb = $thumbdir.$prefix.$userfile_name;
                                         move_uploaded_file($userfile_tmp, $prod_img);
                                         chmod ($prod_img, octdec($mode));
                                         $sizes = getimagesize($prod_img);
                                         $aspect_ratio = $sizes[1]/$sizes[0]; 

                                         if ($sizes[1] <= $size){
                                             $new_width = $sizes[0];
                                             $new_height = $sizes[1];
                                         }else{
                                             $new_height = $size;
                                             $new_width = abs($new_height/$aspect_ratio);
                                         }
                                         $destimg=ImageCreateTrueColor($new_width,$new_height)
                                             or die('Problem In Creating image');

                                        switch($ext){
                                            case "jpg":
                                            case "jpeg":
                                            case "JPG":
                                            case "JPEG":
                                                $srcimg=ImageCreateFromJPEG($prod_img)or die('Problem In opening Source Image');
                                            break;
                                            case "PNG":
                                            case "png":
                                                $srcimg = imageCreateFromPng($prod_img)or die('Problem In opening Source Image');
                                                imagealphablending($destimg, false);
                                                $colorTransparent = imagecolorallocatealpha($destimg, 0, 0, 0x7fff0000);
                                                imagefill($destimg, 0, 0, $colorTransparent);                                                   
                                                imagesavealpha($destimg, true);

                                            break;
                                            case "BMP":
                                            case "bmp":
                                                $srcimg = imageCreateFromBmp($prod_img)or die('Problem In opening Source Image');
                                            break;
                                            case "GIF":
                                            case "gif":
                                                $srcimg = imageCreateFromGif($prod_img)or die('Problem In opening Source Image');
                                            break;
                                            default:
                                                $srcimg=ImageCreateFromJPEG($prod_img)or die('Problem In opening Source Image');
                                        }

                                        if(function_exists('imagecopyresampled')){
                                             imagecopyresampled($destimg,$srcimg,0,0,0,0,$new_width,$new_height,imagesX($srcimg),imagesY($srcimg))
                                             or die('Problem In resizing');
                                         }else{
                                             Imagecopyresized($destimg,$srcimg,0,0,0,0,$new_width,$new_height,imagesX($srcimg),imagesY($srcimg))
                                             or die('Problem In resizing');
                                         }
                                         ImageJPEG($destimg,$prod_img_thumb,90)
                                             or die('Problem In saving');

                                     }
                                unlink($prod_img);
                                echo "<img src='".$prod_img_thumb."'>";
                            }else{
                            echo "Fail upload folder with read access.";
                            }
                    }else{
                    echo "Image file size max 3 MB";
                    }

                }else{
                    echo "Invalid file format..";
                }
            }else{
            echo "Please select image..!";
            }

        exit;
    }
    ?>

Answer 1

<?php
$path = "../userfiles/orig/";
$userpath="../".$_REQUEST['userpath']."/";

function getExtension($str) {
  $i = strrpos($str,".");
  if (!$i) { return ""; }
  $l = strlen($str) - $i;
  $ext = substr($str,$i+1,$l);
  return $ext;
}

$valid_formats = array("jpg", "png", "gif", "bmp","jpeg","PNG","JPG","JPEG","GIF","BMP");

if(isset($_POST) and $_SERVER['REQUEST_METHOD'] == "POST"){
  $name = $_FILES['photoimg']['name'];
  $size = $_FILES['photoimg']['size'];

  if(strlen($name)){
    $ext = getExtension($name);

    if(in_array($ext,$valid_formats)){

      if($size<(2048*2048)){
        $time1=time();
        $actual_image_name =$time1."_".str_replace(" ", "_", $name);
        $tmp = $_FILES['photoimg']['tmp_name'];

        if(move_uploaded_file($tmp, $path.$actual_image_name)){
          $image=$actual_image_name;
          /*--------resize image-----------*/
          $size = 320; // the imageheight
          $filedir = '../userfiles/orig/'; // the directory for the original image
          $thumbdir = $userpath; // the directory for the resized image
          $prefix = $time1.'_'; // the prefix to be added to the original name
          $maxfile = '20000000';
          $mode = '0666';
          $userfile_name =str_replace(" ", "", $_FILES['photoimg']['name']);
          $userfile_tmp = str_replace(" ", "", $_FILES['photoimg']['tmp_name']);
          $userfile_size =$_FILES['photoimg']['size'];
          $userfile_type = $_FILES['photoimg']['type'];

          if (isset($_FILES['photoimg']['name'])){
            $prod_img = $filedir.$actual_image_name;
            $prod_img_thumb = $thumbdir.$prefix.$userfile_name;
            move_uploaded_file($userfile_tmp, $prod_img);
            chmod ($prod_img, octdec($mode));
            $sizes = getimagesize($prod_img);
            $aspect_ratio = $sizes[1]/$sizes[0];

            if ($sizes[1] <= $size){
              $new_width = $sizes[0];
              $new_height = $sizes[1];
            }else{
              $new_height = $size;
              $new_width = abs($new_height/$aspect_ratio);
            }
            $destimg=ImageCreateTrueColor($new_width,$new_height)
            or die('Problem In Creating image');

            switch($ext){
              case "jpg":
              case "jpeg":
              case "JPG":
              case "JPEG":
                $srcimg=ImageCreateFromJPEG($prod_img)or die('Problem In opening Source Image');
                break;
              case "PNG":
              case "png":
                $srcimg = imageCreateFromPng($prod_img)or die('Problem In opening Source Image');
                imagealphablending($destimg, false);
                $colorTransparent = imagecolorallocatealpha($destimg, 0, 0, 0, 0x7fff0000);
                imagefill($destimg, 0, 0, $colorTransparent);
                imagesavealpha($destimg, true);

                break;
              case "BMP":
              case "bmp":
                $srcimg = imageCreateFromBmp($prod_img)or die('Problem In opening Source Image');
                break;
              case "GIF":
              case "gif":
                $srcimg = imageCreateFromGif($prod_img)or die('Problem In opening Source Image');
                break;
              default:
                $srcimg=ImageCreateFromJPEG($prod_img)or die('Problem In opening Source Image');
            }

            if(function_exists('imagecopyresampled')){
              imagecopyresampled($destimg,$srcimg,0,0,0,0,$new_width,$new_height,imagesX($srcimg),imagesY($srcimg))
              or die('Problem In resizing');
            }else{
              Imagecopyresized($destimg,$srcimg,0,0,0,0,$new_width,$new_height,imagesX($srcimg),imagesY($srcimg))
              or die('Problem In resizing');
            }



            // Saving an image
            switch(strtolower($ext)){
              case "jpg":
              case "jpeg":
                ImageJPEG($destimg,$prod_img_thumb,90) or die('Problem In saving');
                break;

              case "png":
                imagepng($destimg,$prod_img_thumb) or die('Problem In saving');
                break;

              case "bmp":
                imagewbmp($destimg, $prod_img_thumb)or die('Problem In saving');
                break;

              case "gif":
                imagegif($destimg,$prod_img_thumb) or die('Problem In saving');
                break;

              default:
                // if image format is unknown, and you whant save it as jpeg, maybe you should change file extension
                imagejpeg($destimg,$prod_img_thumb,90) or die('Problem In saving');
            }



          }
          unlink($prod_img);
          echo "<img src='".$prod_img_thumb."'>";
        }else{
          echo "Fail upload folder with read access.";
        }
      }else{
        echo "Image file size max 3 MB";
      }

    }else{
      echo "Invalid file format..";
    }
  }else{
    echo "Please select image..!";
  }

  exit;
}
?>

Sorry for my english. Problem is it that you trying to save image using imagejpeg, which means new image can't use transparent color anymore. If source image was PNG, you should save it using imagepng.