PHP - 调整透明png和gif大小后的黑色背景

问题描述：

I am using the below code to resize images. When transparent images, (png/gif) are uploaded the new images created have black background. How can i make the background white after resizing? pls help

    $info = pathinfo($_FILES['file']['name']);
    $ext = $info['extension']; // get the extension of the file
    $newname = "testing".".".$ext; 
    $target = 'uploads/'.$newname;
    move_uploaded_file( $_FILES['file']['tmp_name'], $target);;
    $filename=$newname;
    if($ext=='jpg'||$ext=='jpeg') 
    {
        $im = imagecreatefromjpeg('uploads/'.$filename);
    } 
    else if ($ext=='gif') 
    {
        $im = imagecreatefromgif('uploads/'.$filename);
    } 
    else if ($ext=='png') 
    {
        $im = imagecreatefrompng('uploads/'.$filename);
    }
    $ox = imagesx($im);
    $oy = imagesy($im);
    $nm = imagecreatetruecolor(245, 184);
    imagealphablending( $nm, FALSE );
    imagesavealpha( $nm, TRUE );
    imagecopyresized($nm, $im, 0,0,0,0,245,184,$ox,$oy);
    imagejpeg($nm,  'uploads/' . $filename);

我使用以下代码调整图像大小。当上传透明图像（png / gif）时，创建的新图像具有黑色背景。如何在调整大小后使背景变白？请帮助 p>

  $ info = pathinfo（$ _ FILES ['file'] ['name']）; 
 $ ext = $ info ['extension'];  //获取文件的扩展名
 $ newname =“testing”。“。”。$ ext;  
 $ target ='uploads /'.$ newname; 
 move_uploaded_file（$ _FILES ['file'] ['tmp_name']，$ target）;; 
 $ filename = $ newname; 
 if（$ ext =  ='jpg'|| $ ext =='jpeg'）
 {
 $ im = imagecreatefromjpeg（'uploads /'.$ filename）; 
} 
 else if（$ ext =='gif'）\  n {
 $ im = imagecreatefromgif（'uploads /'.$ filename）; 
} 
 else if（$ ext =='png'）
 {
 $ im = imagecreatefrompng（'uploads /'.$  filename）; 
} 
 $ ox = imagesx（$ im）; 
 $ oy = imagesy（$ im）; 
 $ nm = imagecreatetruecolor（245,184）; 
 imagealphablending（$ nm，FALSE）;  
 imagesavealpha（$ nm，TRUE）; 
 imagecopyresized（$ nm，$ im，0,0,0,0,245,184，$ ox，$ oy）; 
 imagejpeg（$ nm，'uploads /'。$ filename）  ; 
  code>  pre> 
  div>

答

Try using

  imagecolortransparent

in your code.

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

PHP - 调整透明png和gif大小后的黑色背景

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