Emoji input: remove context-dependent unicode points from output of emoji palette.

The character palette allowing to input emojis in text generates in some cases a series
of unicode points to represent a single emoji. These series contain various kinds of
unicode points with context-dependent meaning. This commit prevents such context-
dependent unicodepoints from being inserted in FLTK text because FLTK text edition
mechanism is not ready to handle properly context dependency in edited UTF-8 text.

1 files changed, 16 insertions, 1 deletions

diff --git a/src/Fl_cocoa.mm b/src/Fl_cocoa.mm
index 51eeced51..eeeedf425 100644
--- a/src/Fl_cocoa.mm
+++ b/src/Fl_cocoa.mm
@@ -2954,8 +2954,23 @@ static FLTextInputContext* fltextinputcontext_instance = nil;
   BOOL has_text_key = Fl::e_keysym <= '~' || Fl::e_keysym == FL_Iso_Key ||
                       (Fl::e_keysym >= FL_KP && Fl::e_keysym <= FL_KP_Last && Fl::e_keysym != FL_KP_Enter);
   // insertText sent during handleEvent of a key without text cannot be processed in a single FL_KEYBOARD event.
-  // Occurs with deadkey followed by non-text key
+  // Occurs with deadkey followed by non-text key. Occurs also with emoji palette.
   if (!in_key_event || !has_text_key) {
+    if (fl_utf_nb_char((const uchar*)Fl::e_text, Fl::e_length) > 1) {
+      // Some emojis are expressed by a series of Unicode points
+      const char *p = Fl::e_text, *end = Fl::e_text + Fl::e_length;
+      int len;
+      while (p < end) { // loop over all unicode points of the series
+        unsigned u = fl_utf8decode(p, end, &len); // extract one such unicode point
+        if ((u >= 0xFE00 && u <= 0xFE0F)      // variation selectors
+            || u == 0x200D   // zero-width joiner
+            || (u >= 0x1F3FB && u <= 0x1F3FF) // EMOJI MODIFIERS FITZPATRICK TYPE
+            ) { // remove context-dependent unicode points
+          memmove((void*)p, p + len, (end - (p+len)) + 1);
+          Fl::e_length -= len; end -= len;
+        } else p += len; // keep other unicode points
+      }
+    }
     Fl::handle(FL_KEYBOARD, target);
     Fl::e_length = 0;
     }