[easytag] Add album artist support to APE tags

[David King <davidk src gnome org>]

commit 00f216188543d5460d4d10218e304f5fa70a418b
Author: David King <amigadave amigadave com>
Date:   Wed Dec 24 09:37:09 2014 +0000

    Add album artist support to APE tags

 src/tags/ape_tag.c             |   19 +++++++++++++++++++
 src/tags/libapetag/apetaglib.h |    1 +
 2 files changed, 20 insertions(+), 0 deletions(-)
---
diff --git a/src/tags/ape_tag.c b/src/tags/ape_tag.c
index 7e377a6..d808217 100644
--- a/src/tags/ape_tag.c
+++ b/src/tags/ape_tag.c
@@ -86,6 +86,14 @@ ape_tag_read_file_tag (GFile *file,
     if (FileTag->artist == NULL)
         FileTag->artist = Try_To_Validate_Utf8_String(string);
 
+    /* Album artist. */
+    string = apefrm_getstr (ape_cnt, APE_TAG_FIELD_ALBUMARTIST);
+
+    if (FileTag->album_artist == NULL)
+    {
+        FileTag->album_artist = Try_To_Validate_Utf8_String (string);
+    }
+
     /*********
      * Album *
      *********/
@@ -249,6 +257,17 @@ ape_tag_write_file_tag (const ET_File *ETFile,
     else
         apefrm_remove(ape_mem,APE_TAG_FIELD_ARTIST);
 
+    /* Album artist. */
+    if (FileTag->album_artist && g_utf8_strlen (FileTag->album_artist, -1) > 0)
+    {
+        apefrm_add (ape_mem, 0, APE_TAG_FIELD_ALBUMARTIST,
+                    FileTag->album_artist);
+    }
+    else
+    {
+        apefrm_remove (ape_mem, APE_TAG_FIELD_ALBUMARTIST);
+    }
+
     /*********
      * Album *
      *********/
diff --git a/src/tags/libapetag/apetaglib.h b/src/tags/libapetag/apetaglib.h
index 57f08bf..15ab8f2 100644
--- a/src/tags/libapetag/apetaglib.h
+++ b/src/tags/libapetag/apetaglib.h
@@ -80,6 +80,7 @@
 #define APE_TAG_FIELD_TITLE             "Title"
 #define APE_TAG_FIELD_SUBTITLE          "Subtitle"
 #define APE_TAG_FIELD_ARTIST            "Artist"
+#define APE_TAG_FIELD_ALBUMARTIST "Album Artist"
 #define APE_TAG_FIELD_ALBUM             "Album"
 #define APE_TAG_FIELD_PART "Part"
 #define APE_TAG_FIELD_DEBUTALBUM        "Debut Album"