PNG有黑色背景 [英] PNG has black background

问题描述

我正在使用一个lib来轻松保存图像.

I'm using a lib to easy save images.

http://www.white -hat-web-design.co.uk/blog/resizing-images-with-php/

但是问题在于它使用黑色背景保存了透明的png.我搜索了一下，发现了应该起作用但对我不起作用的东西.

But the problem is that it saves transparant png with black background. I have search and found something that should work but is not working for me.

imagecolortransparent()通常应该这样做. 但是对我来说，我仍然看到黑色的背景.

imagecolortransparent() should normally do it. But for me I still see the black background.

我做错了什么?

$imagename = $_FILES['file']['name'];           
$target = "source/images/".$imagename;
$image->save($target);


function save($filename, $image_type=IMAGETYPE_JPEG, $compression=75, $permissions=null){

  if( $image_type == IMAGETYPE_PNG ){

      $image = $this->image;

      $black = imagecolorallocate($image, 0, 0, 0);
      imagecolortransparent($image, $black);

      imagepng($image,$filename);
  }

}

推荐答案

您可能应该更改

$black = imagecolorallocate($im, 0, 0, 0);

到

$black = imagecolorallocate($image, 0, 0, 0);

尝试设置图像Alpha混合

Try setting image alpha blending

imagealphablending($image, false);
imagesavealpha($image, true);

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