如何将 APNG 拆分为 png 图像并通过 PHP 转换为动画 gif

Question

我想通过imagemagick将apng转换为gif，但我不知道该怎么做

我看到Splitting APNG into png images with PHP 我尝试了，但它在我的图像中仍然不起作用 我喜欢
1.ezgif.com/apng-to-gif
2.aconvert.com/image/apng-to-gif

<?php
function splitapng($data) {
  $parts = array();

  // Save the PNG signature   
  $signature = substr($data, 0, 8);
  $offset = 8;
  $size = strlen($data);
  while ($offset < $size) {
    // Read the chunk length
    $length = substr($data, $offset, 4);
    $offset += 4;

    // Read the chunk type
    $type = substr($data, $offset, 4);
    $offset += 4;

    // Unpack the length and read the chunk data including 4 byte CRC
    $ilength = unpack('Nlength', $length);
    $ilength = $ilength['length'];
    $chunk = substr($data, $offset, $ilength+4); 
    $offset += $ilength+4;

    if ($type == 'IHDR')
      $header = $length . $type . $chunk;  // save the header chunk
    else if ($type == 'IEND')
      $end = $length . $type . $chunk;     // save the end chunk
    else if ($type == 'IDAT') 
      $parts[] = $length . $type . $chunk; // save the first frame
    else if ($type == 'fdAT') {
      // Animation frames need a bit of tweaking.
      // We need to drop the first 4 bytes and set the correct type.

      $length = pack('N', $ilength-4);
      $type = 'IDAT';
      $chunk = substr($chunk,4);
      $parts[] = $length . $type . $chunk;
    }
  }

  // Now we just add the signature, header, and end chunks to every part.
  for ($i = 0; $i < count($parts); $i++) {
    $parts[$i] = $signature . $header . $parts[$i] . $end;
  }

  return $parts;
}
$filename = 'A.png';

$handle = fopen($filename, 'rb');
$filesize = filesize($filename);
$data = fread($handle, $filesize);
fclose($handle);

$parts = splitapng($data);

for ($i = 0; $i < count($parts); $i++) {
  $handle = fopen("part-$i.png",'wb');
  fwrite($handle,$parts[$i]);
  fclose($handle);
}


?>

Answer 1

我下载apng2gif
并用这段代码把它和我的 php 放在一起

<?php
header("Content-Type:text/html; charset=utf-8");


$link = substr($_POST["link"],0,-7).'_animation'.substr($_POST["link"],-7);


$linkname = substr($link,57,-32);
function link_code($link) {
  $headers = get_headers($link);
  return substr($headers[0], 9, 3);
}

$link_code = link_code($link);

if( $link_code == 200 ) {
file_put_contents($linkname.".png", fopen($link, 'r'));
  $x = iconv("cp950","UTF-8",shell_exec("apng2gif ".$linkname.".png ".$linkname.".gif"));
  echo "OKAY!";
}
else{
  echo "Nokay!";
}
?>

可以使用 AJAX POST 链接来做 apng2gif 并检查它是否存在
感谢 fmw42 :D