repobrowse: italicize removed lines in diffs

This doesn't look too horrible on displays which render italics
and even degrades gracefully in text-only displays to underline
or colors in other terminals (lynx).  Do not italicize leading
whitespace, since the fallback to underlines looks too noisy.

diff --git a/lib/PublicInbox/RepobrowseGitCommit.pm b/lib/PublicInbox/RepobrowseGitCommit.pm
index 64d0b607352002d33d47d7b616116994b5d1f494..b5ffb2bf3eff1ba981fa8398db48aefa45dcc673 100644 (file)
--- a/lib/PublicInbox/RepobrowseGitCommit.pm
+++ b/lib/PublicInbox/RepobrowseGitCommit.pm
@@ -82,7 +82,7 @@ sub git_commit_stream {
        local $/ = "\n";
        my $cmt = '[a-f0-9]+';
        my $diff = { h => $h, p => \@p, rel => $rel };
-       my $cc_add;
+       my ($cc_ins, $cc_del);
        while (defined($l = <$log>)) {
                if ($help) {
                        $fh->write($help);
@@ -96,11 +96,16 @@ sub git_commit_stream {
                        $l = git_diff_ab_index($diff, $1, $2, $3) . "\n";
                } elsif ($l =~ /^@@ (\S+) (\S+) @@(.*)$/) { # regular
                        $l = git_diff_ab_hunk($diff, $1, $2, $3) . "\n";
-               } elsif ($l =~ /^\+/ || ($cc_add && $l =~ $cc_add)) {
-                       $l = git_diff_add($l) . "\n";
+
+               } elsif ($l =~ /^\+{1,3}\s*/ || ($cc_ins && $l =~ $cc_ins)) {
+                       $l = git_diff_ins($l) . "\n";
+               } elsif ($l =~ s/^(\-{1,3}\s*)// ||
+                                       ($cc_del && $l =~ s/$cc_del//)) {
+                       $l = git_diff_del($1, $l) . "\n";
                } elsif ($l =~ /^index ($cmt,[^\.]+)\.\.($cmt)(.*)$/o) { # --cc
                        $l = git_diff_cc_index($diff, $1, $2, $3) . "\n";
-                       $cc_add ||= $diff->{cc_add};
+                       $cc_ins ||= $diff->{cc_ins};
+                       $cc_del ||= $diff->{cc_del};
                } elsif ($l =~ /^(@@@+) (\S+.*\S+) @@@+(.*)$/) { # --cc
                        $l = git_diff_cc_hunk($diff, $1, $2, $3) . "\n";
                } else {
@@ -278,10 +283,11 @@ sub git_diff_cc_index {
        $end = utf8_html($end);
        my @before = split(',', $before);
        $diff->{pobj_cc} = \@before;
-       $diff->{cc_add} ||= eval {
+       unless ($diff->{cc_ins}) {
                my $n = scalar(@before) - 1;
-               qr/^ {0,$n}[\+]/;
-       };
+               $diff->{cc_ins} = qr/^ {0,$n}[\+]\s*/;
+               $diff->{cc_del} = qr/^( {0,$n}[\-]\s*)/;
+       }
 
        # not wasting bandwidth on links here, yet
        # links in hunk headers are far more useful with line offsets
@@ -346,12 +352,32 @@ sub git_diffstat_rename {
        @base ? "$base/{$from =&gt; $to}" : "$from =&gt; $to";
 }
 
-sub git_diff_add {
+# It would be nice to be able to use colors for showing diff hunks.
+# Unfortunately, the default green+red colors in common web viewers
+# (gitweb, cgit, etc) are difficult to read for some people, myself
+# included.
+#
+# We cannot rely on CSS styling since it is unsafe and incompatible with
+# some browsers.
+#
+# Tried using semantic tags (ins and del).  Unfortunately, alignment
+# gets completely screwed in text-only browsers.  On common GUI browsers,
+# <del> renders unreadably by default (strike-throughs) and <ins> is
+# visually too noisy (with underlines).  So we'll bold added lines and
+# leave deleted lines alone (prefixed with '-')
+sub git_diff_ins {
        my ($l) = @_;
        chomp $l;
        '<b>'.utf8_html($l).'</b>';
 }
 
+sub git_diff_del {
+       my ($pfx, $l) = @_;
+       chomp $l;
+       # underline fallbacks look ugly with leading whitespace
+       $pfx. '<i>'.utf8_html($l).'</i>';
+}
+
 sub git_parent_line {
        my ($pfx, $p, $q, $git, $rel, $path) = @_;
        my $qs = $q->qs(id => $p);