Perl Program list AnalizeJPG.pl 旧版 GetJPGsize.pl

AnalizeJPG.pl(旧版 GetJPGsize.pl)
#!/usr/local/bin/perl
# (c)copyleft 2017-3-19 : Coded by shun kinoshita / knuhs

my $directory = "C:/・・・・・・・・・";  # 適宜書き替える
my $jpgFile1 = "・・・.JPG";  # 適宜書き替える
my $jpgFile2 = "・・・.JPG";  # 適宜書き替える

     open(JPG, "$directory/$jpgFile1") || die "ファイルを開けません。: $!";
     # 一括読み込み
     $/ = undef();  $_ = <JPG>;  $/ = '\n';
     close(JPG);
     # データへのリファランスを渡す
     my ($W, $H) = GetJPGsize(\$_);
     # 結果を出力する
     print "$jpgFile1";
     print "\nWidth:=$W, Height:=$H\n";

# ２度目以上はうまく動作しない。
#    open(JPEG,"$directory/$jpgFile2")|| die "ファイルを開けません。: $!";
#    $/ = undef();  $_ = <JPEG>;  $/ = '\n';
#    close(JPEG);
#    ($W, $H) = GetJPGsize(\$_);
#
#    print "$jpgFile2";
#    print "\nWidth:=$W, Height:=$H\n";
     exit;

#################################################
sub GetJPGsize
{
my $FF=0xFF; #
my $C0=0xC0; #
my $D9=0xD9; #
my $SOI=0xFFD8; # SOI : Start Of Image
my $EOI=0xFFD9; # EOI : End Of Image
my $SOF=0xFFC0; # SOF : Segment Of Frame Header

my ($pos, $W, $H, $count) = (0, 0, 0, 0);
my $jpgRef = shift @_;
my $c;

# get (n) Byte
sub getByte
{  my $n = shift @_;
   my $str ;
   $str = unpack(($n==1)?"C":"n", substr($$jpgRef, $pos, $n)) ;
   $pos += $n;
   return ($str);
}

# start here
  if( getByte(2) != $SOI )  # SOI : Start Of Image
  {  print "JPGファイルではありません！\n"; return(0,0); }

  while(1)
  {  next if( getByte(1) != $FF );
     $c = getByte(1);
     return(-1,-1) if( $c == $D9 ); # EOI : End Of Image
     next if( $c != $C0 ); # SOF : Segment Of Frame Header
     $pos += 3; $H = getByte(2); $W = getByte(2); last;
  }
  return ($W, $H);
}