BMP & GD PHP Support

<?php
function convertBMP2GD($src, $dest = false) {
  if (!($src_f = fopen($src, "rb"))) {
    return false;
  }

  if (!($dest_f = fopen($dest, "wb"))) {
    return false;
  }

  $header = unpack("vtype/Vsize/v2reserved/Voffset", fread($src_f, 14));
  $info = unpack("Vsize/Vwidth/Vheight/vplanes/vbits/Vcompression/Vimagesize/Vxres/Vyres/Vncolor/Vimportant",
  fread($src_f, 40));

  extract($info);
  extract($header);

  if ($type != 0x4D42) { // signature "BM"
    return false;
  }

  $palette_size = $offset - 54;
  $ncolor = $palette_size / 4;
  $gd_header = "";
  // true-color vs. palette
  $gd_header .= ($palette_size == 0) ? "\xFF\xFE" : "\xFF\xFF";
  $gd_header .= pack("n2", $width, $height);
  $gd_header .= ($palette_size == 0) ? "\x01" : "\x00";

  if ($palette_size) {
    $gd_header .= pack("n", $ncolor);
  }

  // no transparency
  $gd_header .= "\xFF\xFF\xFF\xFF";
  fwrite($dest_f, $gd_header);

  if ($palette_size) {
    $palette = fread($src_f, $palette_size);
    $gd_palette = "";
    $j = 0;

    while ($j < $palette_size) {
      $b = $palette{$j++};
      $g = $palette{$j++};
      $r = $palette{$j++};
      $a = $palette{$j++};
      $gd_palette .= "$r$g$b$a";
    }

    $gd_palette .= str_repeat("\x00\x00\x00\x00", 256 - $ncolor);
    fwrite($dest_f, $gd_palette);
  }

  $scan_line_size = (($bits * $width) + 7) >> 3;
  $scan_line_align = ($scan_line_size & 0x03) ? 4 - ($scan_line_size & 0x03) : 0;

  for($i = 0, $l = $height - 1; $i < $height; $i++, $l--) {
    // BMP stores scan lines starting from bottom
    fseek($src_f, $offset + (($scan_line_size + $scan_line_align) * $l));
    $scan_line = fread($src_f, $scan_line_size);
    if ($bits == 24) {
      $gd_scan_line = "";
      $j = 0;
      while ($j < $scan_line_size) {
        $b = $scan_line{$j++};
        $g = $scan_line{$j++};
        $r = $scan_line{$j++};
        $gd_scan_line .= "\x00$r$g$b";
      }
    } elseif ($bits == 8) {
      $gd_scan_line = $scan_line;
    } elseif ($bits == 4) {
      $gd_scan_line = "";
      $j = 0;
      while ($j < $scan_line_size) {
        $byte = ord($scan_line{$j++});
        $p1 = chr($byte >> 4);
        $p2 = chr($byte & 0x0F);
        $gd_scan_line .= "$p1$p2";
      }

      $gd_scan_line = substr($gd_scan_line, 0, $width);
    } elseif ($bits == 1) {
      $gd_scan_line = "";
      $j = 0;
      while ($j < $scan_line_size) {
        $byte = ord($scan_line{$j++});
        $p1 = chr((int) (($byte & 0x80) != 0));
        $p2 = chr((int) (($byte & 0x40) != 0));
        $p3 = chr((int) (($byte & 0x20) != 0));
        $p4 = chr((int) (($byte & 0x10) != 0));
        $p5 = chr((int) (($byte & 0x08) != 0));
        $p6 = chr((int) (($byte & 0x04) != 0));
        $p7 = chr((int) (($byte & 0x02) != 0));
        $p8 = chr((int) (($byte & 0x01) != 0));
        $gd_scan_line .= "$p1$p2$p3$p4$p5$p6$p7$p8";
      }

      $gd_scan_line = substr($gd_scan_line, 0, $width);
    }

    fwrite($dest_f, $gd_scan_line);
  }

  fclose($src_f);
  fclose($dest_f);

  return true;
}

function imagecreatefrombmp($filename) {
  $tmp_name = tempnam("/tmp", "GD");
  if (convertBMP2GD($filename, $tmp_name)) {
    $img = imagecreatefromgd($tmp_name);
    unlink($tmp_name);
    return $img;
  }

  return false;
}