在循环中调整图像大小有时会返回不完整或黑色图像

Question

I've got a bunch of image links I need to download locally on the server. Most requests works fine but every now and then when the job runs scheduled night time, it returns black images. The source is checked and gives the right image.

Rarely it also returns black images with the actual picture in the top left corner but very small.

The array contains about 150 images to get and resize.

First, I download the file:

function downloadFile($url, $path) {
    $file = basename($url);
    $source = file_get_contents($url);
    $fp = fopen($path. $file, 'w');
    set_time_limit(0);
    $options = array(
      CURLOPT_FILE    => $fp,
      CURLOPT_TIMEOUT =>  28800, 
      CURLOPT_URL     => $fp,
    );

    $ch = curl_init();
    curl_setopt_array($ch, $options);
    curl_exec($ch);


    fwrite($fp, $source);

    fclose($fp);
    curl_close($ch);

}

Then resize it:

   function Img_Resize($path) {

       $x = getimagesize($path);            
       $width  = $x['0'];
       $height = $x['1'];

       $rs_width  = 245;//resize to half of the original width.
       $rs_height = 163;//resize to half of the original height.

       switch ($x['mime']) {
          case "image/gif":
             $img = imagecreatefromgif($path);
             break;
          case "image/jpeg":
             $img = imagecreatefromjpeg($path);
             break;
          case "image/jpg":
             $img = imagecreatefromjpeg($path);
             break;
          case "image/png":
             $img = imagecreatefrompng($path);
             break;
       }

       $img_base = imagecreatetruecolor($rs_width, $rs_height);
       imagesetinterpolation($img_base, IMG_BICUBIC);
       imagecopyresampled($img_base, $img, 0, 0, 0, 0, $rs_width, $rs_height, $width, $height);

       $path_info = pathinfo($path);    
       switch ($path_info['extension']) {
          case "gif":
             imagegif($img_base, $path);  
             break;
          case "jpeg":
             imagejpeg($img_base, $path);  
             break;
          case "jpg":
             imagejpeg($img_base, $path);  
             break;
          case "png":
             imagepng($img_base, $path);  
             break;
       }

    }

As follows:

foreach ($URLimages as &$value) {
    if (strpos($value->image, '.jpg')) {
    downloadFile($value->image, $path);
    $test = basename($value->image);
    $img = Img_Resize($path . $test);
    }
}

Answer 1

downloadFile seems to assume everything 'just works'. Life and programming isn't like this.

Below is some of the areas where I would expect a possible error and do something if it happened. You can do this in other ways if you want, such as using try...catch and throwing exceptions.

$source = file_get_contents($url);
if (!$source) { // failed - retry or take other action
    return false;
}

$fp = fopen($path. $file, 'w');
if (!$fp) { // file didn't open ...
    return false;
}

$ch = curl_init();
if (!$ch) { // curl session didn't start ...
    return false;
}

if (!curl_exec( $ch)) { // curl session didn't work
    return false;
}

if (!fwrite($fp, $source)) { // data didn't get written to file
    return false;
}


// return success
return true;
}

Your main code should not try to generate an image for failed downloads:

foreach ($URLimages as &$value) {
  if (strpos($value->image, '.jpg')) {
    if (downloadFile($value->image, $path)) {
      $test = basename($value->image);
      $img = Img_Resize($path . $test);
    }
  }
}