+package Shiar_Sheet::ImagePrep;
+
+use 5.014;
+use warnings;
+
+our $VERSION = '1.00';
+
+sub new {
+ my ($class, $target) = @_;
+ bless \$target, $class;
+}
+
+sub download {
+ # copy changed remote url to local file
+ my $target = shift;
+ unlink $$target if -e $$target;
+ my $download = shift or return 1;
+ require LWP::UserAgent;
+ my $ua = LWP::UserAgent->new;
+ $ua->agent('/');
+ my $status = $ua->mirror($download, $$target);
+ $status->is_success
+ or die "Download from <q>$download</q> failed: ".$status->status_line."\n";
+}
+
+sub convert {
+ my ($imgpath, $thumbpath, $cmds) = @_;
+ if (not -e $$imgpath) {
+ return unlink $thumbpath;
+ }
+
+ my $xyres = 0 ? '600x400' : '300x200'; # cover
+ my @cmds = @{ $cmds // [] };
+ if (my ($cmdarg) = grep { $cmds[$_] eq '-area' } 0 .. $#cmds) {
+ # replace option by permillage crop
+ my @dim = map { $_ / 1000 } split /\D/, $cmds[$cmdarg + 1];
+ splice @cmds, $cmdarg, 2, (
+ -set => 'option:distort:viewport' => sprintf(
+ '%%[fx:w*%s]x%%[fx:h*%s]+%%[fx:w*%s]+%%[fx:h*%s]',
+ ($dim[2] || 1) - $dim[0], # width = x2 - x1
+ ($dim[3] || 1) - $dim[1], # height = y2 - y1
+ @dim[0, 1] # offset = x1,y1
+ ),
+ -distort => SRT => 0, # noop transform to apply viewport
+ );
+ }
+ @cmds = (
+ 'convert',
+ $$imgpath,
+ -delete => '1--1', -background => 'white',
+ -gravity => defined $cmds ? 'northwest' : 'center',
+ @cmds,
+ -resize => "$xyres^", -extent => $xyres,
+ '-strip', -quality => '60%', -interlace => 'plane',
+ $thumbpath
+ );
+
+ require IPC::Run;
+ my $output;
+ IPC::Run::run(\@cmds, '<' => \undef, '>&' => \$output) or die [
+ "Failed to convert source image.",
+ "@cmds\n" .
+ ($output || ($? & 127 ? "signal $?" : "error code ".($? >> 8))),
+ ];
+}
+
+1;