#! /usr/bin/perl -w
#
# Render SVG files containing one or more images into an ICO or BMP.
#
# Copyright (C) 2010 Joel Holdsworth
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA

use strict;
use warnings;
use XML::LibXML;
use MIME::Base64;
use File::Copy;

# Parse the parameters
my $svgFileName = $ARGV[0];
my $outFileName = $ARGV[1];

die "Cannot open SVG file" unless defined($svgFileName);
die "Cannot open output file" unless defined($outFileName);

$outFileName =~ m/(.*)\.(.*)/;
my $outName = $1;
my $ext = lc($2);
die "Only BMP, ICO and CUR outputs are supported" unless $ext eq "bmp" or $ext eq "ico" or $ext eq "cur";

my $renderedSVGFileName = "$svgFileName.png";
my @pngFiles;
my @hotspot;

# Get the programs from the environment variables
my $convert = $ENV{"CONVERT"} || "convert";
my $rsvg = $ENV{"RSVG"} || "rsvg-convert";
my @icotool_args = ($ENV{"ICOTOOL"} || "icotool", "--create",
                    $ext eq "cur" ? "--cursor" : "--icon", "-o", $outFileName);

# Be ready to abort
sub cleanup()
{
    unlink $renderedSVGFileName;
    unlink $_ foreach(@pngFiles);
}

$SIG{"INT"} = "cleanup";
$SIG{"HUP"} = "cleanup";
$SIG{"TERM"} = "cleanup";
$SIG{"__DIE__"} = "cleanup";

my %label =
(
 'ico' => 'icon:(\d*)-(\d*)',
 'cur' => 'cursor:(\d*)-(\d*)',
 'bmp' => 'bitmap:(\d*)-(\d*)',
);

# run a shell command and die on error
sub shell(@)
{
    my @args = @_;
    system(@args) == 0 or die "@args failed: $?";
}

# add an image to the icon/cursor
sub add_image($$)
{
    my ($file, $size) = @_;
    
    if (defined $hotspot[$size])
    {
        my @coords = @{$hotspot[$size]};
        push @icotool_args, "--hotspot-x=$coords[0]", "--hotspot-y=$coords[1]";
    }
    push @icotool_args, $size >= 128 ? "--raw=$file" : $file;
    push @pngFiles, $file;
}

# Render the SVG image
my @rsvgCmd;
push(@rsvgCmd, $rsvg);
push(@rsvgCmd, $svgFileName);
push(@rsvgCmd, "-o") if ($rsvg eq "rsvg-convert");
push(@rsvgCmd, $renderedSVGFileName);
shell @rsvgCmd;

# Render the images in the SVG
my $xml = XML::LibXML->load_xml( location => $svgFileName );
my $xc = XML::LibXML::XPathContext->new($xml);
$xc->registerNs('x', 'http://www.w3.org/2000/svg');

if ($ext eq "bmp")
{
    foreach my $element ($xc->findnodes("/x:svg"))
    {
        next unless $element->{id} =~ /bitmap:(\d*)-(\d*)/;
        my $size = $1;
        my $depth = $2;
        if ($depth == 24) {
            shell $convert, $renderedSVGFileName, "+matte", $outFileName;
        } else {
            shell $convert, $renderedSVGFileName, $outFileName;
        }
        cleanup();
        exit(0);
    }
}

# fetch hotspot rectangles for the various sizes

if ($ext eq "cur")
{
    foreach my $element ($xc->findnodes("/x:svg/x:rect"))
    {
        next unless $element->{id} =~ /hotspot:(\d*)/;
        $hotspot[$1] = [ $element->{x}, $element->{y} ];
    }
}

# extract rectangles from the rendered svg

foreach my $element ($xc->findnodes("/x:svg/*[\@id]"))
{
    next unless $element->{id} =~ /$label{$ext}/;
    my $size = $1;
    my $depth = $2;
    warn "Unexpected depth" unless
        $depth == 1 or $depth == 4 or $depth == 8 or $depth == 24 or $depth == 32;
    my $file = "$outName-$size-$depth.png";

    my $x = $element->{x};
    my $y = $element->{y};
    my $width = $element->{width};
    my $height = $element->{height};
    if ($element->{'xlink:href'})
    {
        # extract base64-encoded png image
        (my $data = $element->{'xlink:href'}) =~ s/data:image\/png;base64//;
        open FILE, ">$file" or die "$!";
        print FILE decode_base64($data);
        close FILE;
    }
    else
    {
        shell $convert, $renderedSVGFileName, "-crop", "${width}x${height}+$x+$y", "-depth", $depth, $file;
    }
    add_image( $file, $size );
}

die "no render directive found in $svgFileName" unless @pngFiles;

shell @icotool_args;

# Delete the intermediate images
cleanup();