#!/usr/bin/perl
######################################################################
#  A Perl::Fu plugin for converting TeX strings to floating layers.
#
#  Author: Dov Grobgeld
#  Version: 0.12
######################################################################

use Gimp;
use Gimp::Fu;

my $fn_base = "/tmp/ttf$$";
my %tmpfiles = (
		"$fn_base.pgm"=>1,
		"$fn_base.tex"=>1,
		"$fn_base.log"=>1,
		"$fn_base.ps"=>1,
		"$fn_base.dvi"=>1);

# Cleanup
sub cleanup {
    foreach my $fn (keys %tmpfiles) {
	unlink $fn;
    }
}

sub xec {
    my $cmd = shift;
    print STDERR "$cmd\n";
    return `$cmd`;
}

sub exist_in_tex_path {
    my $file = shift;

    return 0 unless length($file);
    return 1 if -e $file;
    foreach my $p (split(/:/, $ENV{TEXINPUTS} . ":/tmp")) {
	return 1 if -e "$p/$file";
    }
    return 0;
}

sub tex_string_to_pgm {
    my($text, $input_file, $string, $ppi, $magstep, $anti_aliasing,
       $output_file) = @_;

    my $scale = sprintf("%.5f", 1/$anti_aliasing);
    my $r = $ppi * $anti_aliasing;
    my $device = "pgmraw";

    chdir "/tmp";
    if (exist_in_tex_path($input_file)) {
	$input .= "\\input $input_file\n";
    }

    open(TEX, ">$fn_base.tex");
    print TEX "\\nopagenumbers\n"
	    . "\\magnification\\magstep$magstep\n"
	    . "\\tolerance=8000\n"
	    . "$input\n"
	    . "$string\n"
            . "\\bye";
    close(TEX);

    my $res = xec("tex $fn_base.tex < /dev/null");
    # Deal with errors...

    # Make dvips output bounding box
    my $psoutput = xec("dvips -r$r -E -f $fn_base");
    # Deal with errors

    # Shift postscript file to origin
    my @bbox = $psoutput=~ /^%%BoundingBox:\s*(\d+)\s+(\d+)\s+(\d+)\s+(\d+)/m;
    print STDERR "bbox = @bbox\n";
    my $w = $bbox[2]-$bbox[0];
    my $h = $bbox[3]-$bbox[1];
    $psoutput=~ s/^%%BoundingBox:.*$/%%BoundingBox: 0 0 $w $h/m;
    $psoutput=~ s/^1 0 bop/-$bbox[0] -$bbox[1] translate\n$&/m;

    # Output to file in order not to have to use Open2.
    open(PS, ">$fn_base.ps");
    print PS $psoutput;
    close(PS);
    $w= int($w*$r/72+0.5);
    $h= int($h*$r/72+0.5);

    # Use gs to produce a pgmfile
    my $cmd = "gs -g${w}x${h} -r${r} -dNOPAUSE -q -sDEVICE=$device -sOutputFile=- $fn_base.ps quit.ps |";
    $cmd .= "pnmscale $scale |" if $scale != 1;
    chop($cmd);
    $cmd .= "> $output_file";
    xec("$cmd");
}

sub grey_file_to_float {
    my($img1, $drw1, $fn) = @_;

    # Setup
    my $save_bg = gimp_palette_get_background();
    gimp_undo_push_group_start($img1);

    # Load the new img
    my $grey_img = gimp_file_load(RUN_NONINTERACTIVE, $fn, $fn);

    # Get name of new layer
    my $grey_layer = gimp_image_get_active_layer($grey_img);

    # Create an alpha layer and copy image to alpha layer
    gimp_layer_add_alpha($grey_layer);
    $grey_img->selection_all();
    gimp_edit_copy($grey_layer);
    $mask = gimp_layer_create_mask($grey_layer, 0);
    gimp_image_add_layer_mask($grey_img, $grey_layer, $mask);
    my $floating_layer = gimp_edit_paste($mask, 0);
    gimp_floating_sel_anchor($floating_layer);
    gimp_invert($mask);
    gimp_palette_set_background(gimp_palette_get_foreground());
    gimp_edit_fill($grey_layer);
    gimp_image_remove_layer_mask($grey_img, $grey_layer, 0);

    # Now copy this layer to $img 1
    gimp_edit_copy($grey_layer);
    $floating_layer = gimp_edit_paste($drw1, 0);
    gimp_edit_fill($floating_layer);

    print STDERR "Yohoo!\n";
    cleanup();

    # Get rid of $grey_img
    gimp_image_delete($grey_img);


    # Restore
    gimp_palette_set_background($save_bg);
    gimp_undo_push_group_end($img1);

    # Update the display
    gimp_displays_flush();

    return undef;
}


sub tex_string_to_float {
    my($img1, $drw1,
       $input_file,
       $text,
       $ppi,
       $magstep,
       $anti_aliasing) = @_;


    tex_string_to_pgm($text, $input_file, $text, $ppi, $magstep, $anti_aliasing,
		      "$fn_base.pgm");

    grey_file_to_float($img1, $drw1, "$fn_base.pgm");

    return undef;
}

# register the script
register "tex_string_to_float", "Turn a TeX-string into floating layer", "Takes a TeX string as input and creates a floating layer of the rendered string in the current layer in the foreground color.",
    "Dov Grobgeld <dov\@imagic.weizmann.ac.il>", "Dov Grobgeld",
    "1999-03-16",
    "<Image>/Filters/Render/TeX String",
    "*",
    [
     [PF_STRING,  "input_file",     "TeX macro file to input"],
     [PF_STRING,  "tex_string",     "Enter TeX String"],
     [PF_VALUE,   "dpi",     "Resolution to render the text in",   "72"],
     [PF_VALUE,   "magstep",     "TeX magstep",   "2"],
     [PF_VALUE,   "anti_aliasing",     "Anti-aliasing factor",   "4"],
    ],
    \&tex_string_to_float;

# Handle over control to gimp
exit main();