Make ID3v2 output take less vertical space

From: Petr Baudis <pasky@ucw.cz>

The tags are collapsed to two-column output where possible, and blank
lines and tabs indentation is removed.
---

 src/id3.c |   46 +++++++++++++++++++++++++++++++++++++---------
 1 files changed, 37 insertions(+), 9 deletions(-)

diff --git a/src/id3.c b/src/id3.c
index b7f2bc6..13cbc22 100644
--- a/src/id3.c
+++ b/src/id3.c
@@ -649,16 +649,44 @@ void print_id3_tag(unsigned char *id3v1b
 
 	if(id3.version > 1)
 	{
-		fprintf(stderr,"\n");
 		/* print id3v2 */
-		/* dammed, I use pointers as bool again! It's so convenient... */
-		fprintf(stderr,"\tTitle:   %s\n", id3.title.fill ? id3.title.p : "");
-		fprintf(stderr,"\tArtist:  %s\n", id3.artist.fill ? id3.artist.p : "");
-		fprintf(stderr,"\tAlbum:   %s\n", id3.album.fill ? id3.album.p : "");
-		fprintf(stderr,"\tYear:    %s\n", id3.year.fill ? id3.year.p : "");
-		fprintf(stderr,"\tGenre:   %s\n", id3.genre.fill ? id3.genre.p : "");
-		fprintf(stderr,"\tComment: %s\n", id3.comment.fill ? id3.comment.p : "");
-		fprintf(stderr,"\n");
+		/* We are trying to be smart here and conserve vertical space.
+		 * So we will skip tags not set, and try to show them in two
+		 * parallel columns if they are short, which is by far the
+		 * most common case. */
+		if (id3.title.fill && id3.artist.fill && strlen(id3.title.p) <= 30 && strlen(id3.title.p) <= 30)
+		{
+			fprintf(stderr,"Title  : %-30s  Artist: %s\n",id3.title.p,id3.artist.p);
+		}
+		else
+		{
+			if (id3.title.fill)
+				fprintf(stderr,"Title  : %s\n", id3.title.p);
+			if (id3.artist.fill)
+				fprintf(stderr,"Artist : %s\n", id3.artist.p);
+		}
+		if (id3.comment.fill && id3.album.fill && strlen(id3.comment.p) <= 30 && strlen(id3.album.p) <= 30)
+		{
+			fprintf(stderr,"Comment: %-30s  Album : %s\n",id3.comment.p,id3.album.p);
+		}
+		else
+		{
+			if (id3.comment.fill)
+				fprintf(stderr,"Comment: %s\n", id3.comment.p);
+			if (id3.album.fill)
+				fprintf(stderr,"Album  : %s\n", id3.album.p);
+		}
+		if (id3.year.fill && id3.genre.fill && strlen(id3.year.p) <= 30 && strlen(id3.genre.p) <= 30)
+		{
+			fprintf(stderr,"Year   : %-30s  Genre : %s\n",id3.year.p,id3.genre.p);
+		}
+		else
+		{
+			if (id3.year.fill)
+				fprintf(stderr,"Year   : %s\n", id3.year.p);
+			if (id3.genre.fill)
+				fprintf(stderr,"Genre  : %s\n", id3.genre.p);
+		}
 	}
 	else if(id3v1buf != NULL)
 	{