#!/bin/sh

##############################################################################
# This is essentially a Perl program.  We exec the Perl interpreter specifying
# this same file as the Perl program and use the -x option to cause the Perl
# interpreter to skip down to the Perl code.  The reason we do this instead of
# just making /usr/bin/perl the script interpreter (instead of /bin/sh) is
# that the user may have multiple Perl interpreters and the one he wants to
# use is properly located in the PATH.  The user's choice of Perl interpreter
# may be crucial, such as when the user also has a PERL5LIB environment
# variable and it selects modules that work with only a certain main
# interpreter program.
#
# An alternative some people use is to have /usr/bin/env as the script
# interpreter.  We don't do that because we think the existence and
# compatibility of /bin/sh is more reliable.
#
# Note that we aren't concerned about efficiency because the user who needs
# high efficiency can use directly the programs that this program invokes.
#
##############################################################################

exec perl -w -x -S -- "$0" "$@"

#!/usr/bin/perl
##############################################################################
#                              ppmshadow
##############################################################################
#
#            by John Walker  --  http://www.fourmilab.ch/
#                          version = 1.2;
#   --> with minor changes by Bryan Henderson to adapt to Netbpm.  
#   See above web site for the real John Walker work, named pnmshadow.
#
#   Bryan Henderson later made some major style changes (use strict, etc) and
#   eliminated most use of shells.  See Netbpm HISTORY file.
#
#   Pnmshadow is a brutal sledgehammer implemented in Perl which
#   adds attractive shadows to images, as often seen in titles
#   of World-Wide Web pages.  This program does not actually
#   *do* any image processing--it simply invokes components of
#   Jef Poskanzer's PBMplus package (which must be present on
#   the path when this script is run) to bludgeon the source
#   image into a plausible result.
#
#               This program is in the public domain.
#
##############################################################################

use strict;
use File::Temp;
require 5.0;
#  The good open() syntax, with the mode separate from the file name,
#  came after 5.0.  So did mkdir() with default mode.

my $true=1; my $false=0;



sub doVersionHack($) {
    my ($argvR) = @_;

    my $arg1 = $argvR->[0];

    if (defined($arg1) && (($arg1 eq "--version") || ($arg1 eq "-version"))) {
        my $termStatus = system('pamarith', '--version');
        exit($termStatus == 0 ? 0 : 1);
    }
}



sub imageDimensions($) {
    my ($fileName) = @_;
#-----------------------------------------------------------------------------
#  Return the dimensions of the Netpbm image in the file named $fileName.
#-----------------------------------------------------------------------------
    my ($width, $height, $depth);
    my $pamfileOutput = `pamfile $fileName`;
    if ($pamfileOutput =~
            m/.*\sP[BGP]M\s.*,\s*(\d*)\sby\s(\d*)\s*maxval\s(\d*)/) {
        ($width, $height, $depth) = ($1, $2, $3);
    } else {
        die("Unrecognized output from 'pamfile' shell command");
    }
    return ($width, $height, $depth);
}    

sub backgroundColor($) {
    my ($fileName) = @_;
#-----------------------------------------------------------------------------
#  Return the color of the background of the image in the file named $fileName.
#-----------------------------------------------------------------------------
    # We call the color of the top left pixel the background color.

    my $ppmhistOut = qx{pamcut 0 0 1 1 $fileName | ppmhist -noheader -float};

    my ($ired, $igrn, $iblu, $lum, $count);

    if ($ppmhistOut =~
        m{\s*([01].\d+)\s*([01].\d+)\s*([01].\d+)\s*([01].\d+)\s*(\d+)}) {
        ($ired, $igrn, $iblu, $lum, $count) = ($1, $2, $3, $4, $5);
    } else {
        die("Unrecognized format of output from 'ppmhist' shell command");
    }
    my $irgb = sprintf("rgbi:%f/%f/%f", $ired, $igrn, $iblu);

    return $irgb;
}    



sub makeConvolutionKernel($$) {
    my ($convkernelfile, $ckern) = @_;

    #   Create convolution kernel file to generate shadow
    
    open(OF, ">$convkernelfile") or die();
    printf(OF "P2\n$ckern $ckern\n%d\n", $ckern * $ckern * 2);
    my $a = ($ckern * $ckern) + 1;
    my $i;
    for ($i = 0; $i < $ckern; $i++) {
        my $j;
        for ($j = 0; $j < $ckern; $j++) {
            printf(OF "%d%s", $a, ($j < ($ckern - 1)) ? " " : "\n");
        }
    }
    close(OF);
}



##############################################################################
#                           MAINLINE
##############################################################################

doVersionHack(\@ARGV);

#   Process command line options

my $ifile; # Input file name
my ($xoffset, $yoffset);

my $convolve = 11;                   # Default blur convolution kernel size
my $keeptemp = $false;               # Don't preserve intermediate files
my $translucent = $false;            # Default not translucent

while (@ARGV) {
    my $arg = shift;

    if ((substr($arg, 0, 1) eq '-') && (length($arg) > 1)) {
        my $opt;
        $opt = substr($arg, 1, 1);
        $opt =~ tr/A-Z/a-z/;
        if ($opt eq 'b') {        # -B n  --  Blur size
            if (!defined($convolve = shift)) {
                die("Argument missing after -b option\n");
            }
            if (($convolve < 11) && (($convolve & 1) == 0)) {
                $convolve++;      # Round up even kernel specification
            }
        } elsif ($opt eq 'k') {   # -K  --  Keep temporary files
            $keeptemp = $true;
        } elsif ($opt eq 't') {   # -T  --  Translucent image
            $translucent = $true;
        } elsif ($opt eq 'x') {   # -X n  --  X offset
            if (!defined($xoffset = shift)) {
                die("Argument missing after -x option\n");
            }
            if ($xoffset < 0) {
                $xoffset = -$xoffset;
            }
        } elsif ($opt eq 'y') {   # -Y n  --  Y offset
            if (!defined($yoffset = shift)) {
                die("Argument missing after -x option\n");
            }
            if ($yoffset < 0) {
                $yoffset = -$xoffset;
            }
        } else {
            die("Unknown option '$opt'\n");
        }
    } else {
        if (defined $ifile) {
            die("Duplicate input file specification.");
        }
        $ifile = $arg;   
    }
}

# Create temporary directory

my $tmpdir = $ENV{TMPDIR} || "/tmp";
my $ourtmp;

if ($keeptemp) {
    $ourtmp = "$tmpdir/ppmshadow$$";
    mkdir($ourtmp, 0777) or
        die("Unable to create directory for temporary files '$ourtmp");
} else {
    $ourtmp = File::Temp::tempdir("$tmpdir/ppmshadowXXXX", UNLINK=>1);
}

#   Apply defaults for arguments not specified

if (!(defined $xoffset)) {
    #   Xoffset defaults to half the blur distance
    $xoffset = int($convolve / 2);
}

if (!(defined $yoffset)) {
    #   Yoffset defaults to Xoffset, however specified
    $yoffset = $xoffset;
}

# Save the Standard Output open instance so we can use the STDOUT
# file descriptor to pass files to our children.
open(OLDOUT, ">&STDOUT");
select(OLDOUT);  # avoids Perl bug where it says we never use STDOUT 

my $infile = "$ourtmp/infile.ppm";

if (defined($ifile) && $ifile ne "-") {
    open(STDIN, "<$ifile") or die();
}
open(STDOUT, ">$infile") or die("Unable to open '$infile' as STDOUT");
system("ppmtoppm");

# You would think we could and should close stdin and stdout now, but if
# we do that, system() pipelines later on fail mysteriously.  They don't
# seem to be able to open stdin and stdout pipes properly if stdin and 
# stdout didn't already exist.  2002.09.07 BJH

my ($sourceImageWidth, $sourceImageHeight, $sourceImageDepth) =
    imageDimensions($infile);

my $bgColorIrgb = backgroundColor($infile);

# Create an all-background-color image (same size as original image),
# named $backgroundfile. 

my $backgroundfile = "$ourtmp/background.ppm";
system("ppmmake $bgColorIrgb $sourceImageWidth $sourceImageHeight " .
    "-maxval $sourceImageDepth " .
    ">$backgroundfile");

# Create mask file for background, named $bgmaskfile.  It is a PBM, white
# wherever there is background image in the input.

my $bgmaskfile = "$ourtmp/bgmask.pbm";
system("ppmchange -remainder=black $bgColorIrgb white $infile | " .
       "ppmtopgm | pgmtopbm -threshold -value=0.5 >$bgmaskfile"); 

my $ckern = $convolve <= 11 ? $convolve : 11;

my $convkernelfile = "$ourtmp/convkernel.pgm";

makeConvolutionKernel($convkernelfile, $ckern);

if ($translucent) {

    #   Convolve the input color image with the kernel
    #   to create a translucent shadow image.

    system("pnmconvol -quiet $convkernelfile $infile >$ourtmp/blurred.ppm");
    unlink("$convkernelfile") unless $keeptemp;
    while ($ckern < $convolve) {
        system("pnmsmooth $ourtmp/blurred.ppm >$ourtmp/convolvedx.ppm");
        rename("$ourtmp/convolvedx.ppm", "$ourtmp/blurred.ppm");
        ++$ckern;
    }
} else {

    #   Convolve the positive mask with the kernel to create shadow
 
    my $blurredblackshadfile = "$ourtmp/blurredblackshad.pgm";
    system("pamdepth -quiet $sourceImageDepth $bgmaskfile | " .
           "pnmconvol -quiet $convkernelfile >$blurredblackshadfile");
    unlink($convkernelfile) unless $keeptemp;

    while ($ckern < $convolve) {
        my $smoothedfile = "$ourtmp/smoothed.pgm";
        system("pnmsmooth $blurredblackshadfile >$smoothedfile");
        rename($smoothedfile, $blurredblackshadfile);
        ++$ckern;
    }

    #   Multiply the shadow by the background color

    system("pamarith -multiply $blurredblackshadfile $backgroundfile " .
           ">$ourtmp/blurred.ppm");
    unlink($blurredblackshadfile) unless $keeptemp;
}

#   Cut shadow image down to size of our frame.

my $shadowfile = "$ourtmp/shadow.ppm";
{
    my $width = $sourceImageWidth - $xoffset;
    my $height = $sourceImageHeight - $yoffset;
    open(STDIN, "<$ourtmp/blurred.ppm") or die();
    open(STDOUT, ">$shadowfile") or die();
    system("pamcut", "-left=0", "-top=0", 
           "-width=$width", "-height=$height");
}
unlink("$ourtmp/blurred.ppm") unless $keeptemp;


#   Paste shadow onto background.

my $shadbackfile = "$ourtmp/shadback.ppm";
open(STDOUT, ">$shadbackfile") or die();
system("pnmpaste", "-replace", $shadowfile, $xoffset, $yoffset,
       $backgroundfile);
unlink($shadowfile) unless $keeptemp;
unlink($backgroundfile) unless $keeptemp;


#   Create composite file, send to original Standard Output.

open(STDOUT, ">&OLDOUT");

system("pamcomp -invert -alpha $bgmaskfile $infile $shadbackfile");
unlink($bgmaskfile) unless $keeptemp;
unlink($infile) unless $keeptemp;
unlink($shadbackfile) unless $keeptemp;

if (!$keeptemp) {
    rmdir($ourtmp) or die ("Unable to remove temporary directory '$ourtmp'");
}
