pngquant和shell_exec检查状态码，然后保存图像

Question

我有下面的代码，它似乎正在生成一个损坏的图像。Photoshop显示"PNG文件被ASCII转换损坏“

    $path_pngquant = "pngquant";
    $status_code = null;
    $image = null;
    $output = null;

    $image_input_escaped = escapeshellarg('test.png');

    $command = "$path_pngquant --strip -- - < $image_input_escaped";

    // Execute the command
    exec($command, $output, $status_code);

    if($status_code == 0)
    {
        //0 means success
        $image = implode('', $output);
        file_put_contents('test_2.png', $image);
    }

Answer 1

exec会弄乱二进制流，您需要的是以二进制模式打开从其读取的输出流。幸运的是，popen正是为此而设计的

    <?php
 $path_pngquant = "pngquant";
    $status_code = null;
    $image = null;
    $output = null;

    $image_input_escaped = escapeshellarg('test.png');

    $command = "$path_pngquant --strip -- - < $image_input_escaped";

    // Execute the command
    $handle = popen($command . '2>&1', 'rb'); //MODE : r =read ; b = binary 

    if($handle){
        $output = '';

        while (!feof($handle)) {
            echo $output;
            $output .= fread($handle, 10240); //10240 = 10kb ; read in chunks of 10kb , change it as per need
        }
        fclose($handle);
     
        file_put_contents('test_2.png', $output);
    }

2>&1是在常用shell脚本中使用的redirection syntax