Question

我试图保留PNG或GIF图像的透明度，但是使用我生成缩略图的代码，我得到的是图像的黑色背景而不是透明。

这是我的代码：

function create_image($source_image_path, $thumbnail_image_path, $real_width, $real_height,$source_image_height,$source_image_width)
{
   list($source_image_width, $source_image_height, $source_image_type) =     getimagesize($source_image_path);
$source_gd_image = false;
switch ($source_image_type) {
    case IMAGETYPE_GIF:
        $source_gd_image = imagecreatefromgif($source_image_path);
        break;
    case IMAGETYPE_JPEG:
        $source_gd_image = imagecreatefromjpeg($source_image_path);
        break;
    case IMAGETYPE_PNG:
        $source_gd_image = imagecreatefrompng($source_image_path);
        break;
}
if ($source_gd_image === false) {
    return false;
}


$thumbnail_gd_image = imagecreatetruecolor($real_width, $real_height);
if(($source_image_type == 1) || ($source_image_type==3)){
    imagealphablending($thumbnail_gd_image, false);
    imagesavealpha($thumbnail_gd_image, true);
    $transparent = imagecolorallocatealpha($thumbnail_gd_image, 255, 255, 255, 127);
    imagefilledrectangle($thumbnail_gd_image, 0, 0, $real_width, $real_height, $transparent);
}

imagecopyresampled($thumbnail_gd_image, $source_gd_image, 0, 0, 0, 0, $real_width, $real_height, $source_image_width, $source_image_height);
imagejpeg($thumbnail_gd_image, $thumbnail_image_path, 100);
imagedestroy($source_gd_image);
imagedestroy($thumbnail_gd_image);
return true;
}

使用上面的代码，我得到了黑色的图像背景。

我尝试使用imagecolorallocate($thumbnail_gd_image, 255, 255, 255);。但是这个imagefilledrectangle()给了我白色背景。

有人可以帮助我获得PNG或GIF图像的透明背景吗？

Answer 1

我认为你的问题在下面一行：

$thumbnail_gd_image = imagecreatetruecolor($real_width, $real_height);

根据http://www.php.net/manual/en/function.imagecreatetruecolor.php

imagecreatetruecolor（）返回表示指定大小的黑色图像的图像标识符。

使用PHP代码生成缩略图时，如何保留PNG图像透明度

1 个答案: