Add a sample program 'blameview' to show how to use git-blame --incremental

Signed-off-by: Junio C Hamano <junkio@cox.net>

contrib/blameview/README

@@ -0,0 +1,10 @@
+This is a sample program to use 'git-blame --incremental', based
+on this message.
+
+From: Jeff King <peff@peff.net>
+Subject: Re: More precise tag following
+To: Linus Torvalds <torvalds@linux-foundation.org>
+Cc: git@vger.kernel.org
+Date: Sat, 27 Jan 2007 18:52:38 -0500
+Message-ID: <20070127235238.GA28706@coredump.intra.peff.net>
+

contrib/blameview/blameview.perl

@@ -0,0 +1,118 @@
+#!/usr/bin/perl
+
+use Gtk2 -init;
+use Gtk2::SimpleList;
+
+my $fn = shift or die "require filename to blame";
+
+Gtk2::Rc->parse_string(<<'EOS');
+style "treeview_style"
+{
+  GtkTreeView::vertical-separator = 0
+}
+class "GtkTreeView" style "treeview_style"
+EOS
+
+my $window = Gtk2::Window->new('toplevel');
+$window->signal_connect(destroy => sub { Gtk2->main_quit });
+my $scrolled_window = Gtk2::ScrolledWindow->new;
+$window->add($scrolled_window);
+my $fileview = Gtk2::SimpleList->new(
+    'Commit' => 'text',
+    'CommitInfo' => 'text',
+    'FileLine' => 'text',
+    'Data' => 'text'
+);
+$scrolled_window->add($fileview);
+$fileview->get_column(0)->set_spacing(0);
+$fileview->set_size_request(1024, 768);
+$fileview->set_rules_hint(1);
+
+open(my $fh, '<', $fn)
+  or die "unable to open $fn: $!";
+while(<$fh>) {
+  chomp;
+  $fileview->{data}->[$.] = ['HEAD', '?', "$fn:$.", $_];
+}
+
+my $blame;
+open($blame, '-|', qw(git blame --incremental --), $fn)
+    or die "cannot start git-blame $fn";
+
+Glib::IO->add_watch(fileno($blame), 'in', \&read_blame_line);
+
+$window->show_all;
+Gtk2->main;
+exit 0;
+
+my %commitinfo = ();
+
+sub flush_blame_line {
+	my ($attr) = @_;
+
+	return unless defined $attr;
+
+	my ($commit, $s_lno, $lno, $cnt) =
+	    @{$attr}{qw(COMMIT S_LNO LNO CNT)};
+
+	my ($filename, $author, $author_time, $author_tz) =
+	    @{$commitinfo{$commit}}{qw(FILENAME AUTHOR AUTHOR-TIME AUTHOR-TZ)};
+	my $info = $author . ' ' . format_time($author_time, $author_tz);
+
+	for(my $i = 0; $i < $cnt; $i++) {
+		@{$fileview->{data}->[$lno+$i-1]}[0,1,2] =
+		    (substr($commit, 0, 8), $info,
+		     $filename . ':' . ($s_lno+$i));
+	}
+}
+
+my $buf;
+my $current;
+sub read_blame_line {
+
+	my $r = sysread($blame, $buf, 1024, length($buf));
+	die "I/O error" unless defined $r;
+
+	if ($r == 0) {
+		flush_blame_line($current);
+		$current = undef;
+		return 0;
+	}
+
+	while ($buf =~ s/([^\n]*)\n//) {
+		my $line = $1;
+
+		if (($commit, $s_lno, $lno, $cnt) =
+		    ($line =~ /^([0-9a-f]{40}) (\d+) (\d+) (\d+)$/)) {
+			flush_blame_line($current);
+			$current = +{
+				COMMIT => $1,
+				S_LNO => $2,
+				LNO => $3,
+				CNT => $4,
+			};
+			next;
+		}
+
+		# extended attribute values
+		if ($line =~ /^(author|author-mail|author-time|author-tz|committer|committer-mail|committer-time|committer-tz|summary|filename) (.*)$/) {
+			my $commit = $current->{COMMIT};
+			$commitinfo{$commit}{uc($1)} = $2;
+			next;
+		}
+	}
+	return 1;
+}
+
+sub format_time {
+  my $time = shift;
+  my $tz = shift;
+
+  my $minutes = $tz < 0 ? 0-$tz : $tz;
+  $minutes = ($minutes / 100)*60 + ($minutes % 100);
+  $minutes = $tz < 0 ? 0-$minutes : $minutes;
+  $time += $minutes * 60;
+  my @t = gmtime($time);
+  return sprintf('%04d-%02d-%02d %02d:%02d:%02d %s',
+		 $t[5] + 1900, @t[4,3,2,1,0], $tz);
+}