PHP中无法创建WebP图片缩略图，提示服务器GD函数不支持

问题重现 #

开发图片上传及缩略图生成功能时，除WebP格式外其余图片处理均正常，上传WebP图片时失败，报错：

"Your server does not support the GD function required to process this type of image"

用户代码如下：

$imagePrefix = time(); 
$imagename = "img_".$imagePrefix.trim($_FILES['file']['name']);
$config['upload_path'] = 'uploads/nft/'; 
$config['allowed_types'] = 'jpg|jpeg|png|gif|PNG|JPG|JPEG|avif|webp'; 
$config['file_name'] = $imagename; 
$this->load->library('upload',$config); 
if($this->upload->do_upload('file'))
{ 
    $uploadData = $this->upload->data(); 
    $filename = $uploadData['file_name']; 
    $datas=$_POST;
    $data = $this->upload->data();
    $this->load->library('image_lib');
    $config2['image_library'] = 'gd2';
    $config2['source_image'] = $uploadData['full_path'];
    $config2['new_image'] = './uploads/nft/thumb/'.$uploadData["raw_name"].$uploadData['file_ext'];
    $config2['create_thumb'] = TRUE;
    $config2['maintain_ratio'] = FALSE;
    $config2['width'] = 350;
    $config2['height'] = 350;
    $this->image_lib->initialize($config2);

    $this->image_lib->clear();
}

问题原因 #

1. 服务器GD库未启用WebP支持：GD2处理WebP依赖imagecreatefromwebp()和imagewebp()两个核心函数，若服务器编译PHP时未加入WebP扩展，这两个函数不存在就会触发报错。
2. CodeIgniter image_lib调用遗漏：原代码初始化image_lib后未调用resize()方法，这是缩略图生成的关键步骤，同时旧版image_lib对WebP的适配逻辑可能不完善。

解决步骤 #

1. 验证服务器GD的WebP支持 #

创建测试脚本test_gd_webp.php，执行以下代码：

<?php
var_dump(function_exists('imagecreatefromwebp'));
var_dump(function_exists('imagewebp'));
phpinfo();
?>

• 若两个函数返回true，说明GD支持WebP，问题出在CodeIgniter配置；
• 若返回false，需先开启服务器GD的WebP支持。

2. 开启GD的WebP支持 #

• Ubuntu/Debian服务器：

  sudo apt-get install php-webp
  sudo systemctl restart apache2 # 或nginx，根据你的Web服务调整
  

• 编译PHP时添加支持：
  重新编译PHP，配置参数加入：

  --with-webp
  

3. 调整CodeIgniter代码适配WebP #

补全缩略图生成逻辑，并针对WebP做特殊处理：

if($this->upload->do_upload('file'))
{ 
    $uploadData = $this->upload->data(); 
    $filename = $uploadData['file_name']; 
    $datas=$_POST;
    $data = $this->upload->data();

    // 针对WebP格式单独处理
    if($uploadData['file_ext'] === '.webp') {
        if(!function_exists('imagecreatefromwebp') || !function_exists('imagewebp')) {
            die("服务器不支持WebP图片处理");
        }
        // 手动生成WebP缩略图
        $source = imagecreatefromwebp($uploadData['full_path']);
        $thumb = imagecreatetruecolor(350, 350);
        imagecopyresampled($thumb, $source, 0, 0, 0, 0, 350, 350, imagesx($source), imagesy($source));
        $thumbPath = './uploads/nft/thumb/'.$uploadData["raw_name"].$uploadData['file_ext'];
        imagewebp($thumb, $thumbPath);
        // 释放资源
        imagedestroy($source);
        imagedestroy($thumb);
    } else {
        // 原有格式使用image_lib处理，补全resize()调用
        $this->load->library('image_lib');
        $config2['image_library'] = 'gd2';
        $config2['source_image'] = $uploadData['full_path'];
        $config2['new_image'] = './uploads/nft/thumb/'.$uploadData["raw_name"].$uploadData['file_ext'];
        $config2['create_thumb'] = TRUE;
        $config2['maintain_ratio'] = FALSE;
        $config2['width'] = 350;
        $config2['height'] = 350;
        $this->image_lib->initialize($config2);
        $this->image_lib->resize();
        $this->image_lib->clear();
    }
}

内容的提问来源于stack exchange，提问作者Ellyse