From 448f1f629d8b01b48164ee0560d5596b8c5d9be0 Mon Sep 17 00:00:00 2001
From: zakk4223 <zakk@rsdio.com>
Date: Wed, 23 Jul 2025 02:33:30 -0400
Subject: [PATCH] Bumper l/r or -/+ -> prev/next letter in file picker (#1007)

---
 file_io.cpp | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 file_io.h   |  2 ++
 menu.cpp    | 10 +++++++--
 3 files changed, 69 insertions(+), 2 deletions(-)

diff --git a/file_io.cpp b/file_io.cpp
index da6f899..774a732 100644
--- a/file_io.cpp
+++ b/file_io.cpp
@@ -1838,6 +1838,65 @@ int ScanDirectory(char* path, int mode, const char *extension, int options, cons
 				if (iFirstEntry < 0) iFirstEntry = 0;
 			}
 		}
+		else if (mode == SCANF_NEXT_CHAR)
+		{
+			//DirItem is sorted, so just advance until the first character changes.
+			//if we reach the end before that don't change anything.
+			//If we change d_type also consider that 'next'. This means next
+			//advances through directories, and then advances through files
+
+			int found = -1;
+			char curChar = toupper(DirItem[iSelectedEntry].altname[0]);
+			char curdType = DirItem[iSelectedEntry].de.d_type;
+			for (int i = iSelectedEntry+1; i < flist_nDirEntries(); i++)
+			{
+				if (toupper(DirItem[i].altname[0]) != curChar || DirItem[i].de.d_type != curdType)
+				{
+					found = i;
+					break;
+				}
+			}
+
+			if (found >= 0)
+			{
+				iSelectedEntry = found;
+				if (iSelectedEntry + (OsdGetSize() / 2) >= flist_nDirEntries()) iFirstEntry = flist_nDirEntries() - OsdGetSize();
+				else iFirstEntry = iSelectedEntry - (OsdGetSize()/2) + 1;
+				if (iFirstEntry < 0) iFirstEntry = 0;
+			}
+		}
+		else if (mode == SCANF_PREV_CHAR)
+		{
+
+			//Previous seek seeks to the FIRST entry that starts with the previous letter
+			//Search backward until the first char changes, and then continue looking backward
+			//until it changes again. 
+			int found = -1;
+			bool sawChange = false;
+			char curChar = toupper(DirItem[iSelectedEntry].altname[0]);
+			char curdType = DirItem[iSelectedEntry].de.d_type;
+			for (int i = iSelectedEntry-1; i >= 0; i--)
+			{
+				if (toupper(DirItem[i].altname[0]) != curChar || DirItem[i].de.d_type != curdType)
+				{
+					if (sawChange)
+					{
+						found = i+1;
+						break;
+					}
+					sawChange = true;
+					curChar = toupper(DirItem[i].altname[0]);
+				}
+			}
+
+			if (found >= 0)
+			{
+				iSelectedEntry = found;
+				if (iSelectedEntry + (OsdGetSize() / 2) >= flist_nDirEntries()) iFirstEntry = flist_nDirEntries() - OsdGetSize();
+				else iFirstEntry = iSelectedEntry - (OsdGetSize()/2) + 1;
+				if (iFirstEntry < 0) iFirstEntry = 0;
+			}
+		}
 		else
 		{
 			//printf("dir scan for key: %x/%c\n", mode, mode);
diff --git a/file_io.h b/file_io.h
index 04a724e..e69cd61 100644
--- a/file_io.h
+++ b/file_io.h
@@ -63,6 +63,8 @@ char* flist_GetPrevNext(const char* base_path, const char* file, const char* ext
 #define SCANF_PREV_PAGE -2 // find previous 16 files in directory
 #define SCANF_SET_ITEM   3 // find exact item
 #define SCANF_END        4 // find last file in directory
+#define SCANF_NEXT_CHAR  5 // find next letter/number
+#define SCANF_PREV_CHAR -5 // find previous letter/number
 
 // options flags
 #define SCANO_DIR        0b000000001 // include subdirectories
diff --git a/menu.cpp b/menu.cpp
index ba4d739..aeeec61 100644
--- a/menu.cpp
+++ b/menu.cpp
@@ -514,7 +514,7 @@ static uint32_t menu_key_get(void)
 		else if (CheckTimer(repeat))
 		{
 			repeat = GetTimer(REPEATRATE);
-			if (GetASCIIKey(c1) || ((menustate == MENU_COMMON2) && (menusub == 17)) || ((menustate == MENU_SYSTEM2) && (menusub == 5)))
+			if (GetASCIIKey(c1) || menustate == MENU_FILE_SELECT2 || ((menustate == MENU_COMMON2) && (menusub == 17)) || ((menustate == MENU_SYSTEM2) && (menusub == 5)))
 			{
 				c = c1;
 				hold_cnt++;
@@ -1240,7 +1240,7 @@ void HandleUI(void)
 		}
 	}
 
-	if (menu || select || up || down || left || right || (helptext_idx_old != helptext_idx))
+	if (menu || select || up || down || left || right || plus || minus || (helptext_idx_old != helptext_idx))
 	{
 		helptext_idx_old = helptext_idx;
 		if (helpstate) OsdWrite(OsdGetSize()-1, STD_EXIT, (menumask - ((1 << (menusub + 1)) - 1)) <= 0, 0); // Redraw the Exit line...
@@ -5090,6 +5090,12 @@ void HandleUI(void)
 				menustate = MENU_FILE_SELECT1;
 			}
 
+			if (plus || minus) 
+			{
+				ScanDirectory(selPath, plus ? SCANF_NEXT_CHAR : SCANF_PREV_CHAR, fs_pFileExt, fs_Options);
+				menustate = MENU_FILE_SELECT1;
+			}
+
 			{
 				char i;
 				if ((i = GetASCIIKey(c)) > 1)