在php中创建图像时，透明图像出现黑色背景[重复]

Question

我正在使用以下代码在 php 中编写水印代码，但对于透明图像，黑色背景即将到来：

$font_path                = $_SERVER['DOCUMENT_ROOT'] . "/fonts/arial.ttf"; // Font file
$water_mark_text_2        = "IndustrialStores.com"; // Watermark Text
list($owidth,$oheight)    = getimagesize($oldimage_name);

$width    = $owidth;
$height   = $oheight; 
$image    = imagecreatetruecolor($width, $height);

$extension = pathinfo($oldimage_name, PATHINFO_EXTENSION);
$extension = strtolower($extension);

if($extension=="jpg" || $extension=="jpeg" ){
    $image_src = imagecreatefromjpeg($oldimage_name);
}
else if($extension=="png"){
    $image_src = imagecreatefrompng($oldimage_name);
}
else if($extension=="gif"){
    $image_src = imagecreatefromgif($oldimage_name);
}
else if($extension=="bmp"){
    $image_src = imagecreatefrombmp($oldimage_name);
}
else{
    copy($oldimage_name, $new_image_name);    
    unlink($oldimage_name);
    return true;
}

imagecopyresampled($image, $image_src, 0, 0, 0, 0, $width, $height, $owidth, $oheight);
$blue = imagecolorallocate ($image, 179, 179, 179);
$bbox = imageftbbox($width/15, 0, $font_path, 'IndustrialStores.com');

$x = $bbox[0] + (imagesx($image) / 2) - ($bbox[4] / 2);
$y = $bbox[1] + (imagesy($image) / 2) - ($bbox[5] / 2) - 5;

imagettftext($image, $width/15, 0, $x, $y, $blue, $font_path, $water_mark_text_2);
imagejpeg($image, $new_image_name, 100);
imagedestroy($image);
unlink($oldimage_name);

我已经尝试过很多其他的 * 答案，比如使用：

$im = imagecreatetruecolor(55, 30);
$red = imagecolorallocate($im, 255, 0, 0);
$black = imagecolorallocate($im, 0, 0, 0);

// Make the background transparent
imagecolortransparent($im, $black);

但这一切都没有用

Answer 1

添加这些行会有帮助吗？

else{
    copy($oldimage_name, $new_image_name);    
    unlink($oldimage_name);
    return true;
}

// add these lines here!
imagealphablending($image, false);
imagesavealpha($image, true);

imagecopyresampled($image, $image_src, 0, 0, 0, 0, $width, $height, $owidth, $oheight);
$blue = imagecolorallocate ($image, 179, 179, 179);