From 5c7c1498d0f9560dda7fad6bda93d3c1d373c11f Mon Sep 17 00:00:00 2001
From: Holger Schemel <holger.schemel@virtion.de>
Date: Sun, 27 Mar 2022 14:54:40 +0200
Subject: [PATCH] added cursor key navigation to music info screens

---
 src/files.c   | 12 ++++++++++++
 src/main.h    |  2 +-
 src/screens.c | 12 ++++++------
 3 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/src/files.c b/src/files.c
index a2efae2a..307b7889 100644
--- a/src/files.c
+++ b/src/files.c
@@ -13430,6 +13430,18 @@ void LoadMusicInfo(void)
 	new = &(*new)->next;
     }
   }
+
+  // add pointers to previous list nodes
+
+  struct MusicFileInfo *node = music_file_info;
+
+  while (node != NULL)
+  {
+    if (node->next)
+      node->next->prev = node;
+
+    node = node->next;
+  }
 }
 
 static void add_helpanim_entry(int element, int action, int direction,
diff --git a/src/main.h b/src/main.h
index 3d6055a8..b4a57291 100644
--- a/src/main.h
+++ b/src/main.h
@@ -3715,7 +3715,7 @@ struct MusicFileInfo
 
   boolean is_sound;
 
-  struct MusicFileInfo *next;
+  struct MusicFileInfo *prev, *next;
 };
 
 struct ElementActionInfo
diff --git a/src/screens.c b/src/screens.c
index 816f01ed..c3c87f24 100644
--- a/src/screens.c
+++ b/src/screens.c
@@ -279,7 +279,7 @@ static void DrawInfoScreen_HelpText(int, int, int, int);
 static void HandleInfoScreen_Main(int, int, int, int, int);
 static void HandleInfoScreen_TitleScreen(int);
 static void HandleInfoScreen_Elements(int);
-static void HandleInfoScreen_Music(int);
+static void HandleInfoScreen_Music(int, int, int);
 static void HandleInfoScreen_Credits(int, int, int);
 static void HandleInfoScreen_Program(int);
 static void HandleInfoScreen_Version(int);
@@ -3199,12 +3199,12 @@ static void DrawInfoScreen_Music(void)
 
   LoadMusicInfo();
 
-  HandleInfoScreen_Music(MB_MENU_INITIALIZE);
+  HandleInfoScreen_Music(0, 0, MB_MENU_INITIALIZE);
 
   FadeIn(REDRAW_FIELD);
 }
 
-void HandleInfoScreen_Music(int button)
+void HandleInfoScreen_Music(int dx, int dy, int button)
 {
   static struct MusicFileInfo *list = NULL;
   int font_title = MENU_INFO_FONT_TITLE;
@@ -3250,14 +3250,14 @@ void HandleInfoScreen_Music(int button)
 
     return;
   }
-  else if (button == MB_MENU_CHOICE || button == MB_MENU_INITIALIZE)
+  else if (button == MB_MENU_CHOICE || button == MB_MENU_INITIALIZE || dx)
   {
     if (button != MB_MENU_INITIALIZE)
     {
       PlaySound(SND_MENU_ITEM_SELECTING);
 
       if (list != NULL)
-	list = list->next;
+	list = (dx < 0 ? list->prev : list->next);
     }
 
     if (list == NULL)
@@ -4064,7 +4064,7 @@ void HandleInfoScreen(int mx, int my, int dx, int dy, int button)
   else if (info_mode == INFO_MODE_ELEMENTS)
     HandleInfoScreen_Elements(button);
   else if (info_mode == INFO_MODE_MUSIC)
-    HandleInfoScreen_Music(button);
+    HandleInfoScreen_Music(dx, dy, button);
   else if (info_mode == INFO_MODE_CREDITS)
     HandleInfoScreen_Credits(dx, dy, button);
   else if (info_mode == INFO_MODE_PROGRAM)
-- 
2.34.1