All platforms use same code to remove context-dependent codepoints from text input.

This commit introduces function fl_utf8_remove_context_dependent() that removes
from an UTF-8 string its context-dependent codepoints. Platforms macOS, Wayland
and X11 call this function to process UTF-8 text received from a character palette
as input to FLTK text. This makes sure FLTK text-editing widgets process textual input
equally and consistently across platforms, especially emojis entered via a palette.

Platform Windows creates a series of separate system events to input an emoji
via the character palette. For this reason, function fl_utf8_remove_context_dependent()
is not used by this platform which does internally the same filtering of context-
dependent codepoints.

1 files changed, 3 insertions, 1 deletions

diff --git a/src/Fl_x.cxx b/src/Fl_x.cxx
index fa58c8076..150438755 100644
--- a/src/Fl_x.cxx
+++ b/src/Fl_x.cxx
@@ -1,7 +1,7 @@
 //
 // X specific code for the Fast Light Tool Kit (FLTK).
 //
-// Copyright 1998-2025 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
@@ -101,6 +101,7 @@ extern Fl_Window *fl_xmousewin;
 
 static void open_display_i(Display *d); // open display (internal)
 extern int fl_send_system_handlers(void *e);
+extern int fl_utf8_remove_context_dependent(char *text, int len);
 
 #if FLTK_CONSOLIDATE_MOTION
 static Fl_Window *send_motion;
@@ -1833,6 +1834,7 @@ int fl_handle(const XEvent& thisevent)
         Status status;
         len = XUtf8LookupString(Fl_X11_Screen_Driver::xim_ic, (XKeyPressedEvent *)&xevent.xkey,
                              kp_buffer, kp_buffer_len, &keysym, &status);
+        len = fl_utf8_remove_context_dependent(kp_buffer, len);
 
         while (status == XBufferOverflow && kp_buffer_len < 50000) {
           kp_buffer_len = kp_buffer_len * 5 + 1;