Let Fl_Text_Editor and Fl_Input handle gracefully composed unicode characters.

1 files changed, 13 insertions, 5 deletions

diff --git a/src/Fl_Input.cxx b/src/Fl_Input.cxx
index fd66d8f24..bd317ad09 100644
--- a/src/Fl_Input.cxx
+++ b/src/Fl_Input.cxx
@@ -1,7 +1,7 @@
 //
 // Input widget for the Fast Light Tool Kit (FLTK).
 //
-// Copyright 1998-2024 by Bill Spitzak and others.
+// Copyright 1998-2026 by Bill Spitzak and others.
 //
 // This library is free software. Distribution and use rights are outlined in
 // the file "COPYING" which should have been included with this file.  If this
@@ -190,14 +190,20 @@ int Fl_Input::kf_delete_eol() {
 int Fl_Input::kf_delete_char_right() {
   if (readonly()) { fl_beep(); return 1; }
   if (mark() != insert_position()) cut();
-  else cut(1);
+  else {
+    const char *next = fl_utf8_next_composed_char(value() + insert_position(), value() + size());
+    replace(insert_position(), next - value(), 0);
+  }
   return 1;
 }
 
 int Fl_Input::kf_delete_char_left() {
   if (readonly()) { fl_beep(); return 1; }
   if (mark() != insert_position()) cut();
-  else cut(-1);
+  else {
+    const char *before = fl_utf8_previous_composed_char(value() + insert_position(), value());
+    replace(insert_position(), before - value(), 0);
+  }
   return 1;
 }
 
@@ -225,7 +231,8 @@ int Fl_Input::kf_clear_eol() {
 //    If OPTION_ARROW_FOCUS is disabled, return 1 to prevent focus navigation.
 //
 int Fl_Input::kf_move_char_left() {
-  int i = shift_position(insert_position()-1) + NORMAL_INPUT_MOVE;
+  const char *before = fl_utf8_previous_composed_char(value() + insert_position(), value());
+  int i = shift_position(before - value()) + NORMAL_INPUT_MOVE;
   return Fl::option(Fl::OPTION_ARROW_FOCUS) ? i : 1;
 }
 
@@ -233,7 +240,8 @@ int Fl_Input::kf_move_char_left() {
 //    If OPTION_ARROW_FOCUS is disabled, return 1 to prevent focus navigation.
 //
 int Fl_Input::kf_move_char_right() {
-  int i = shift_position(insert_position()+1) + NORMAL_INPUT_MOVE;
+  const char *next = fl_utf8_next_composed_char(value() + insert_position(), value() + size());
+  int i = shift_position(next - value()) + NORMAL_INPUT_MOVE;
   return Fl::option(Fl::OPTION_ARROW_FOCUS) ? i : 1;
 }