上傳透明圖片添加黑色背景

Question

我正在嘗試做一個函數來處理頭像上傳。 我的問題是，當我上傳一個透明的圖像，它調整後，它把所有透明的黑色。

我試過使用imageavephapha（）& imagealphablending（）選項，但背景仍然變黑。

這可能只是我盲目，沒有看到代碼中的問題，但我不知道它爲什麼這樣做。

我可以確認，在圖片剛剛上傳後移動到圖片/頭像文件夾後，背景仍然是透明的。

這是我當前的代碼，我一直在測試與png格式圖片：

function upload_avatar(){ 
    $base_path = SYSTEM_PATH; 

    if($_FILES['avatar_img']['tmp_name'] != '') { 
     $id = md5($this->user_id()); 
     $filename = $_FILES['avatar_img']['name']; 
     $file_basename = substr($filename, 0, strripos($filename, '.')); // strip extention 
     $file_ext = substr($filename, strripos($filename, '.')); // strip name 
     $filesize = $_FILES['avatar_img']['size']; 
     $newfilename = $id . $file_ext; 

     if ($file_ext == ".jpg" || $file_ext == ".JPG" || $file_ext == ".jpeg" || $file_ext == ".png" || $file_ext == ".gif"){ 
      if($filesize <= 153600){ 

       move_uploaded_file($_FILES['avatar_img']['tmp_name'], $base_path."/images/avatars/" . $newfilename); 

       //resize image form 
       list($width, $height) = getimagesize($base_path."/images/avatars/" . $newfilename); 
       $scale_height = $height/$width; 
       $scale_width = $width/$height; 

       //Find height and width of the image 
       if($width > $height && $width > 150){ 
        $width_new = 150; 
        $height_new = round($width_new*$scale_height); 
       }else if($height > $width && $height > 150){ 
        $height_new = 150; 
        $width_new = round($height_new*$scale_width); 
       }else{ 
        $height_new = $height; 
        $width_new = $width; 
       } 

       switch($file_ext) { 
        case ".jpg" : 
         case ".jpeg": 
          $source = imagecreatefromjpeg($base_path."/images/avatars/" . $newfilename); 
        break; 

        case ".png" : 
         $source = imagecreatefrompng($base_path."/images/avatars/" . $newfilename); 
        break; 

        default: 
         $source = imagecreatefromgif($base_path."/images/avatars/" . $newfilename); 
        break; 
       } 

       $destination = imagecreatetruecolor($width_new, $height_new); 

       imagesavealpha($destination, true); 
       imagealphablending($destination, true); 

       imagecopyresized($destination, $source, 0, 0, 0, 0, $width_new, $height_new, $width, $height); 

       switch($file_ext) { 
        case ".jpg": 
        case ".jpeg": 
         imagejpeg($destination, $base_path."/images/avatars/" . $newfilename, 85); 
        break; 

        case ".png": 
         imagepng($destination, $base_path."/images/avatars/" . $newfilename, 8); 
        break; 

        default: 
         imagegif($destination, $base_path."/images/avatars/" . $newfilename, 85); 
        break; 
       } 

       return $newfilename; 
      }else{ 
       $this->upload_avatar = '<br />But the avatar was not updated. The avatar\'s size exceeded the 150kb limit. '; 
       return ''; 
      } 
     }else{ 
      $this->upload_avatar = '<br />But the avatar was not updated. The avatar must be one of the following formats: jpg, jpeg, png or gif. '; 
      return ''; 
     } 
    }else{ 
     return ''; 
    } 
} 

任何幫助，因爲我要瘋了這個現在正在尋找可以理解的。

謝謝！

Answer 1

This here可能是你在找什麼。第二個評論包含一個在保持透明度的同時調整png和gif的例子。

p.s.我已經添加了這個作爲評論，但我沒有權利這樣做。