发信人: tanshuai()
整理人: workingnow(2002-09-30 11:46:09), 站内信件
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#!/usr/bin/perl
###下面的内容都是从perl的模块:Image:Size复制过来的
###你使用Image:Size模块也可以得到上述功能,但是你必须有安装模块的权限.
###如果你没有,那么你可以使用这个文件
###用法:函数用法相同,使用require "yourpath/imgsize.pl";
####例如:
#-- #!/usr/bin/perl
#--
#-- require "imgsize.pl";
#--
#-- my($xx, $yy) = &imgsize("c:/temp/test.gif");
#-- print "xx:$xx yy:$yy\n";
#--
#-- exit;
#--
use strict;
use Cwd 'cwd';
use File::Spec;
use Symbol;
use vars qw($read_in $last_pos);
my %cache = ();
my %type_map = ( '^GIF8[7,9]a' => \&gifsize,
"^\xFF\xD8" => \&jpegsize,
"^\x89PNG\x0d\x0a\x1a\x0a" => \&pngsize,
"^P[1-7]" => \&ppmsize, # also XVpic
s
'\#define\s+\S+\s+\d+' => \&xbmsize,
'\/\* XPM \*\/' => \&xpmsize,
'^MM\x00\x2a' => \&tiffsize,
'^II\x2a\x00' => \&tiffsize,
'^BM' => \&bmpsize);
my $read_io = sub {
my $handle = shift;
my ($length, $offset) = @_;
if (defined($offset) && ($offset != $last_pos))
{
$last_pos = $offset;
return '' if (! seek($handle, $offset, 0));
}
my ($data, $rtn) = ('', 0);
$rtn = read $handle, $data, $length;
$data = '' unless ($rtn);
$last_pos = tell $handle;
$data;
};
my $read_buf = sub {
my $buf = shift;
my ($length, $offset) = @_;
if (defined($offset) && ($offset != $last_pos))
{
$last_pos = $offset;
return '' if ($last_pos > length($$buf));
}
my $data = substr($$buf, $last_pos, $length);
$last_pos += length($data);
$data;
};
sub imgsize
{
my $stream = shift;
my ($handle, $header);
my ($x, $y, $id, $mtime, @list);
# These only used if $stream is an existant open FH
my ($save_pos, $need_restore) = (0, 0);
$header = '';
if (ref($stream) eq "SCALAR")
{
$handle = $stream;
$read_in = $read_buf;
$header = substr($$handle, 0, 256);
}
elsif (ref $stream)
{
#
# I no longer require $stream to be in the IO::* space. So I'm
assuming
# you don't hose yourself by passing a ref that can't do fileo
ps. If
# you do, you fix it.
#
$handle = $stream;
$read_in = $read_io;
$save_pos = tell $handle;
$need_restore = 1;
#
# First alteration (didn't wait long, did I?) to the existant
handle:
#
# assist dain-bramaged operating systems -- SWD
# SWD: I'm a bit uncomfortable with changing the mode on a fil
e
# that something else "owns" ... the change is global, and the
re
# is no way to reverse it.
# But image files ought to be handled as binary anyway.
#
binmode($handle);
seek($handle, 0, 0);
read $handle, $header, 256;
seek($handle, 0, 0);
}
else
{
#$stream = cwd . "/$stream" unless ($stream =~ m|^/|);
$stream = File::Spec->catfile(cwd(),$stream) unless File::Spec->file_
name_is_absolute($stream);
$mtime = (stat $stream)[9];
if (-e "$stream" and exists $cache{$stream})
{
@list = split(/,/, $cache{$stream}, 4);
# Don't return the cache if the file is newer.
return @list[1 .. 3] unless ($list[0] < $mtime);
# In fact, clear it
delete $cache{$stream};
}
#first try to open the stream
$handle = gensym;
open($handle, "< $stream") or
return (undef, undef, "Can't open image file $stream: $!")
;
# assist dain-bramaged operating systems -- SWD
binmode($handle);
read $handle, $header, 256;
seek($handle, 0, 0);
$read_in = $read_io;
}
$last_pos = 0;
#
# Oh pessimism... set the values of $x and $y to the error conditi
on. If
# the grep() below matches the data to one of the known types, the
n the
# called subroutine will override these...
#
$id = "Data stream is not a known image file format";
$x = undef;
$y = undef;
grep($header =~ /$_/ && (($x, $y, $id) = &{$type_map{$_}}($handle)
),
keys %type_map);
#
# Added as an afterthought: I'm probably not the only one who uses
the
# same shaded-sphere image for several items on a bulleted list:
#
$cache{$stream} = join(',', $mtime, $x, $y, $id)
unless (ref $stream or (! defined $x));
#
# If we were passed an existant file handle, we need to restore th
e
# old filepos:
#
seek($handle, $save_pos, 0) if ($need_restore);
# results:
return (wantarray) ? ($x, $y, $id) : ();
}
sub gifsize
{
my $stream = shift;
my ($cmapsize, $buf, $h, $w, $x, $y, $type);
my $gif_blockskip = sub {
my ($skip, $type) = @_;
my ($lbuf);
&$read_in($stream, $skip); # Skip header (if any)
while (1)
{
if (&img_eof($stream))
{
return (undef, undef,
"Invalid/Corrupted GIF (at EOF in GIF $type)")
;
}
$lbuf = &$read_in($stream, 1); # Block size
last if ord($lbuf) == 0; # Block terminator
&$read_in($stream, ord($lbuf)); # Skip data
}
};
$type = &$read_in($stream, 6);
if (length($buf = &$read_in($stream, 7)) != 7 )
{
return (undef, undef, "Invalid/Corrupted GIF (bad header)");
}
($x) = unpack("x4 C", $buf);
if ($x & 0x80)
{
$cmapsize = 3 * (2**(($x & 0x07) + 1));
if (! &$read_in($stream, $cmapsize))
{
return (undef, undef,
"Invalid/Corrupted GIF (global color map too small
?)");
}
}
FINDIMAGE:
while (1)
{
if (&img_eof($stream))
{
return (undef, undef,
"Invalid/Corrupted GIF (at EOF w/o Image Descripto
rs)");
}
$buf = &$read_in($stream, 1);
($x) = unpack("C", $buf);
if ($x == 0x2c)
{
# Image Descriptor (GIF87a, GIF89a 20.c.i)
if (length($buf = &$read_in($stream, 8)) != 8)
{
return (undef, undef,
"Invalid/Corrupted GIF (missing image header?)
");
}
($x, $w, $y, $h) = unpack("x4 C4", $buf);
$x += $w * 256;
$y += $h * 256;
return ($x, $y, 'GIF');
}
if ($x == 0x21)
{
# Extension Introducer (GIF89a 23.c.i, could also be in GI
F87a)
$buf = &$read_in($stream, 1);
($x) = unpack("C", $buf);
if ($x == 0xF9)
{
# Graphic Control Extension (GIF89a 23.c.ii)
&$read_in($stream, 6); # Skip it
next FINDIMAGE; # Look again for Image Descripto
r
}
elsif ($x == 0xFE)
{
# Comment Extension (GIF89a 24.c.ii)
&$gif_blockskip(0, "Comment");
next FINDIMAGE; # Look again for Image Descripto
r
}
elsif ($x == 0x01)
{
# Plain Text Label (GIF89a 25.c.ii)
&$gif_blockskip(13, "text data");
next FINDIMAGE; # Look again for Image Descripto
r
}
elsif ($x == 0xFF)
{
# Application Extension Label (GIF89a 26.c.ii)
&$gif_blockskip(12, "application data");
next FINDIMAGE; # Look again for Image Descripto
r
}
else
{
return (undef, undef,
sprintf("Invalid/Corrupted GIF (Unknown " .
"extension %#x)", $x));
}
}
else
{
return (undef, undef,
sprintf("Invalid/Corrupted GIF (Unknown code %#x)"
,
$x));
}
}
}
sub img_eof
{
my $stream = shift;
return ($last_pos >= length($$stream)) if (ref($stream) eq "SCALAR
");
eof $stream;
}
# jpegsize: gets the width and height (in pixels) of a jpeg file
# Andrew Tong, [email protected] February 14, 1995
# modified slightly by [email protected]
# and further still by [email protected]
# optimization and general re-write from [email protected]
sub jpegsize
{
my $stream = shift;
my $MARKER = "\xFF"; # Section marker.
my $SIZE_FIRST = 0xC0; # Range of segment identifier code
s
my $SIZE_LAST = 0xC3; # that hold size info.
my ($x, $y, $id) = (undef, undef, "could not determine JPEG size")
;
my ($marker, $code, $length);
my $segheader;
# Dummy read to skip header ID
&$read_in($stream, 2);
while (1)
{
$length = 4;
$segheader = &$read_in($stream, $length);
# Extract the segment header.
($marker, $code, $length) = unpack("a a n", $segheader);
# Verify that it's a valid segment.
if ($marker ne $MARKER)
{
# Was it there?
$id = "JPEG marker not found";
last;
}
elsif ((ord($code) >= $SIZE_FIRST) && (ord($code) <= $SIZE_LAS
T))
{
# Segments that contain size info
$length = 5;
($y, $x) = unpack("xnn", &$read_in($stream, $length));
$id = 'JPG';
last;
}
else
{
# Dummy read to skip over data
&$read_in($stream, ($length - 2));
}
}
($x, $y, $id);
}
# ppmsize: gets data on the PPM/PGM/PBM family.
#
# Contributed by Carsten Dominik <[email protected]>
sub ppmsize
{
my $stream = shift;
my ($x, $y, $id) = (undef, undef,
"Unable to determine size of PPM/PGM/PBM data"
);
my $n;
my $header = &$read_in($stream, 1024);
# PPM file of some sort
$header =~ s/^\#.*//mg;
($n, $x, $y) = ($header =~ /^(P[1-6])\s+(\d+)\s+(\d+)/s);
$id = "PBM" if $n eq "P1" || $n eq "P4";
$id = "PGM" if $n eq "P2" || $n eq "P5";
$id = "PPM" if $n eq "P3" || $n eq "P6";
if ($n eq 'P7')
{
# John Bradley's XV thumbnail pics (thanks to [email protected]
et.COM)
$id = 'XV';
($x, $y) = ($header =~ /IMGINFO:(\d+)x(\d+)/s);
}
($x, $y, $id);
}
# tiffsize: size a TIFF image
#
# Contributed by Cloyce Spradling <[email protected]>
sub tiffsize
{
my $stream = shift;
my ($x, $y, $id) = (undef, undef, "Unable to determine size of TIF
F data");
my $endian = 'n'; # Default to big-endian; I like it bet
ter
my $header = &$read_in($stream, 4);
$endian = 'v' if ($header =~ /II\x2a\x00/o); # little-endian
# Set up an association between data types and their corresponding
# pack/unpack specification. Don't take any special pains to deal
with
# signed numbers; treat them as unsigned because none of the image
# dimensions should ever be negative. (I hope.)
my @packspec = ( undef, # nothing (shouldn't happen)
'C', # BYTE (8-bit unsigned integer)
undef, # ASCII
$endian, # SHORT (16-bit unsigned integer)
uc($endian), # LONG (32-bit unsigned integer)
undef, # RATIONAL
'c', # SBYTE (8-bit signed integer)
undef, # UNDEFINED
$endian, # SSHORT (16-bit unsigned integer)
uc($endian), # SLONG (32-bit unsigned integer)
);
my $offset = &$read_in($stream, 4, 4); # Get offset to IFD
$offset = unpack(uc($endian), $offset); # Fix it so we can use it
my $ifd = &$read_in($stream, 2, $offset); # Get number of director
y entries
my $num_dirent = unpack($endian, $ifd); # Make it useful
$offset += 2;
$num_dirent = $offset + ($num_dirent * 12); # Calc. maximum offset
of IFD
# Do all the work
$ifd = '';
my $tag = 0;
my $type = 0;
while (!defined($x) || !defined($y)) {
$ifd = &$read_in($stream, 12, $offset); # Get first directory
entry
last if (($ifd eq '') || ($offset > $num_dirent));
$offset += 12;
$tag = unpack($endian, $ifd); # ...and decode its tag
$type = unpack($endian, substr($ifd, 2, 2)); # ...and the data
type
# Check the type for sanity.
next if (($type > @packspec+0) || (!defined($packspec[$type]))
);
if ($tag == 0x0100) { # ImageWidth (x)
# Decode the value
$x = unpack($packspec[$type], substr($ifd, 8, 4));
} elsif ($tag == 0x0101) { # ImageLength (y)
# Decode the value
$y = unpack($packspec[$type], substr($ifd, 8, 4));
}
}
# Decide if we were successful or not
if (defined($x) && defined($y)) {
$id = 'TIF';
} else {
$id = '';
$id = 'ImageWidth ' if (!defined($x));
if (!defined ($y)) {
$id .= 'and ' if ($id ne '');
$id .= 'ImageLength ';
}
$id .= 'tag(s) could not be found';
}
($x, $y, $id);
}
# bmpsize: size a Windows-ish BitMaP image
#
# Adapted from code contributed by Aldo Calpini <a.calpini@romagiubile
o.it>
sub bmpsize
{
my ($stream) = shift;
my ($x, $y, $id) = (undef, undef, "Unable to determine size of TIF
F data");
my ($buffer);
$buffer = &$read_in($stream, 26);
($x, $y) = unpack("x18VV", $buffer);
$id = 'BMP' if (defined $x and defined $y);
($x, $y, $id);
}
sub html_imgsize
{
my @args = imgsize(@_);
# Use lowercase and quotes so that it works with xhtml.
return ((defined $args[0]) ?
sprintf('width="%d" height="%d"', @args) :
undef);
}
sub attr_imgsize
{
my @args = imgsize(@_);
return ((defined $args[0]) ?
(('-width', '-height', @args)[0, 2, 1, 3]) :
undef);
}
sub xbmsize
{
my $stream = shift;
my $input;
my ($x, $y, $id) = (undef, undef, "Could not determine XBM size");
$input = &$read_in($stream, 1024);
if ($input =~ /^\#define\s*\S*\s*(\d+)\s*\n\#define\s*\S*\s*(\d+)/
si)
{
($x, $y) = ($1, $2);
$id = 'XBM';
}
($x, $y, $id);
}
# Added by Randy J. Ray, 30 Jul 1996
# Size an XPM file by looking for the "X Y N W" line, where X and Y ar
e
# dimensions, N is the total number of colors defined, and W is the wi
dth of
# a color in the ASCII representation, in characters. We only care abo
ut X & Y.
sub xpmsize
{
my $stream = shift;
my $line;
my ($x, $y, $id) = (undef, undef, "Could not determine XPM size");
while ($line = &$read_in($stream, 1024))
{
next unless ($line =~ /"\s*(\d+)\s+(\d+)(\s+\d+\s+\d+){1,2}\s*
"/s);
($x, $y) = ($1, $2);
$id = 'XPM';
last;
}
($x, $y, $id);
}
# pngsize : gets the width & height (in pixels) of a png file
# cor this program is on the cutting edge of technology! (pity it's bl
unt!)
#
# Re-written and tested by [email protected]
sub pngsize
{
my $stream = shift;
my ($x, $y, $id) = (undef, undef, "could not determine PNG size");
my ($offset, $length);
# Offset to first Chunk Type code = 8-byte ident + 4-byte chunk le
ngth + 1
$offset = 12; $length = 4;
if (&$read_in($stream, $length, $offset) eq 'IHDR')
{
# IHDR = Image Header
$length = 8;
($x, $y) = unpack("NN", &$read_in($stream, $length));
$id = 'PNG';
}
($x, $y, $id);
}
1;
=head1 NAME
Image::Size - read the dimensions of an image in several popular forma
ts
=head1 SYNOPSIS
use Image::Size;
# Get the size of globe.gif
($globe_x, $globe_y) = imgsize("globe.gif");
# Assume X=60 and Y=40 for remaining examples
use Image::Size 'html_imgsize';
# Get the size as 'width="X" height="Y"' for HTML generation
$size = html_imgsize("globe.gif");
# $size == 'width="60" height="40"'
use Image::Size 'attr_imgsize';
# Get the size as a list passable to routines in CGI.pm
@attrs = attr_imgsize("globe.gif");
# @attrs == ('-width', 60, '-height', 40)
use Image::Size;
# Get the size of an in-memory buffer
($buf_x, $buf_y) = imgsize($buf);
=head1 DESCRIPTION
The B<Image::Size> library is based upon the C<wwwis> script written b
y
Alex Knowles I<([email protected])>, a tool to examine HTML and add 'width
' and
'height' parameters to image tags. The sizes are cached internally bas
ed on
file name, so multiple calls on the same file name (such as images use
d
in bulleted lists, for example) do not result in repeated computations
.
B<Image::Size> provides three interfaces for possible import:
=over
=item imgsize(I<stream>)
Returns a three-item list of the X and Y dimensions (width and height,
in
that order) and image type of I<stream>. Errors are noted by undefined
(B<undef>) values for the first two elements, and an error string in t
he third.
The third element can be (and usually is) ignored, but is useful when
sizing data whose type is unknown.
=item html_imgsize(I<stream>)
Returns the width and height (X and Y) of I<stream> pre-formatted as a
single
string C<'width="X" height="Y"'> suitable for addition into generated
HTML IMG
tags. If the underlying call to C<imgsize> fails, B<undef> is returned
. The
format returned should be dually suited to both HTML and XHTML.
=item attr_imgsize(I<stream>)
Returns the width and height of I<stream> as part of a 4-element list
useful
for routines that use hash tables for the manipulation of named parame
ters,
such as the Tk or CGI libraries. A typical return value looks like
C<("-width", X, "-height", Y)>. If the underlying call to C<imgsize> f
ails,
B<undef> is returned.
=back
By default, only C<imgsize()> is imported. Any one or
combination of the three may be imported, or all three may be with the
tag B<:all>.
=head2 Input Types
The sort of data passed as I<stream> can be one of three forms:
=over
=item string
If an ordinary scalar (string) is passed, it is assumed to be a file n
ame
(either absolute or relative to the current working directory of the
process) and is searched for and opened (if found) as the source of da
ta.
Possible error messages (see DIAGNOSTICS below) may include file-acces
s
problems.
=item scalar reference
If the passed-in stream is a scalar reference, it is interpreted as po
inting
to an in-memory buffer containing the image data.
# Assume that &read_data gets data somewhere (WWW, etc.)
$img = &read_data;
($x, $y, $id) = imgsize(\$img);
# $x and $y are dimensions, $id is the type of the image
=item Open file handle
The third option is to pass in an open filehandle (such as an object o
f
the C<IO::File> class, for example) that has already been associated w
ith
the target image file. The file pointer will necessarily move, but wil
l be
restored to its original position before subroutine end.
# $fh was passed in, is IO::File reference:
($x, $y, $id) = imgsize($fh);
# Same as calling with filename, but more abstract.
=back
=head2 Recognizd Formats
Image::Size understands and sizes data in the following formats:
=over
=item
GIF
=item
JPG
=item
XBM
=item
XPM
=item
PPM family (PPM/PGM/PBM)
=item
PNG
=item
TIF
=item
BMP
=back
When using the C<imgsize> interface, there is a third, unused value re
turned
if the programmer wishes to save and examine it. This value is the thr
ee-
letter identity of the data type. This is useful when operating on ope
n
file handles or in-memory data, where the type is as unknown as the si
ze.
The two support routines ignore this third return value, so those wish
ing to
use it must use the base C<imgsize> routine.
=head1 DIAGNOSTICS
The base routine, C<imgsize>, returns B<undef> as the first value in i
ts list
when an error has occured. The third element contains a descriptive
error message.
The other two routines simply return B<undef> in the case of error.
=head1 MORE EXAMPLES
The B<attr_imgsize> interface is also well-suited to use with the Tk
extension:
$image = $widget->Photo(-file => $img_path, attr_imgsize($img_path
));
Since the C<Tk::Image> classes use dashed option names as C<CGI> does,
no
further translation is needed.
This package is also well-suited for use within an Apache web server c
ontext.
File sizes are cached upon read (with a check against the modified tim
e of
the file, in case of changes), a useful feature for a B<mod_perl> envi
ronment
in which a child process endures beyond the lifetime of a single reque
st.
Other aspects of the B<mod_perl> environment cooperate nicely with thi
s
module, such as the ability to use a sub-request to fetch the full pat
hname
for a file within the server space. This complements the HTML generati
on
capabilities of the B<CGI> module, in which C<CGI::img> wants a URL bu
t
C<attr_imgsize> needs a file path:
# Assume $Q is an object of class CGI, $r is an Apache request obj
ect.
# $imgpath is a URL for something like "/img/redball.gif".
$r->print($Q->img({ -src => $imgpath,
attr_imgsize($r->lookup_uri($imgpath)->filenam
e) }));
The advantage here, besides not having to hard-code the server documen
t root,
is that Apache passes the sub-request through the usual request lifecy
cle,
including any stages that would re-write the URL or otherwise modify i
t.
=head1 CAVEATS
Caching of size data can only be done on inputs that are file names. O
pen
file handles and scalar references cannot be reliably transformed into
a
unique key for the table of cache data. Buffers could be cached using
the
MD5 module, and perhaps in the future I will make that an option. I do
not,
however, wish to lengthen the dependancy list by another item at this
time.
=head1 SEE ALSO
C<http://www.tardis.ed.ac.uk/~ark/wwwis/> for a description of C<wwwis
>
and how to obtain it.
=head1 AUTHORS
Perl module interface by Randy J. Ray I<([email protected])>, original
image-sizing code by Alex Knowles I<([email protected])> and Andrew Tong
I<([email protected])>, used with their joint permission.
Some bug fixes submitted by Bernd Leibing I<([email protected].
de)>.
PPM/PGM/PBM sizing code contributed by Carsten Dominik
I<([email protected])>. Tom Metro I<([email protected])> re-wrote
the JPG
and PNG code, and also provided a PNG image for the test suite. Dan Kl
ein
I<([email protected])> contributed a re-write of the GIF code. Cloyce
Spradling
I<([email protected])> contributed TIFF sizing code and test images.
Aldo
Calpini I<([email protected])> suggested support of BMP images
(which
I I<really> should have already thought of :-) and provided code to wo
rk
with. A patch to allow html_imgsize to produce valid output for XHTML,
as
well as some documentation fixes was provided by Charles Levert
I<([email protected])>.
=cut
--
※ 修改:．tanshuai 于 Nov 19 17:03:53 修改本文．[FROM: 61.137.184.229]
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