Re: [PATCH] emoji on TUI emacs

From cacd2fca920c8203826702ac877ad8716d9b8ed4 Mon Sep 17 00:00:00 2001
From: Kai Ma <[email protected]>
Date: Thu, 30 Jul 2026 16:24:28 +0200
Subject: [PATCH] Produce padding glyphs for composition strings.

* src/term.c (append_composite_glyphs): Produce (pixel_width - 1)
padding glyphs.  Renamed from append_composite_glyph.
(append_composite_glyph): Renamed to append_composite_glyphs.
(produce_composite_glyph): Change its comment and the number of glyphs.
(encode_terminal_code): Skip padding glyphs first.
---
 src/term.c | 105 +++++++++++++++++++++++++++++++----------------------
 1 file changed, 61 insertions(+), 44 deletions(-)

diff --git a/src/term.c b/src/term.c
index 52ae4f61814..75769a7e91c 100644
--- a/src/term.c
+++ b/src/term.c
@@ -567,6 +567,13 @@ encode_terminal_code (struct glyph *src, int src_len,
   nchars = 0;
   while (src < src_end)
     {
+      /* We must skip glyphs to be padded for a wide character.  */
+      if (CHAR_GLYPH_PADDING_P (*src))
+	{
+	  src++;
+	  continue;
+	}
+
       if (src->type == COMPOSITE_GLYPH)
 	{
 	  struct composition *cmp;
@@ -632,8 +639,7 @@ encode_terminal_code (struct glyph *src, int src_len,
 		nchars++;
 	      }
 	}
-      /* We must skip glyphs to be padded for a wide character.  */
-      else if (! CHAR_GLYPH_PADDING_P (*src))
+      else
 	{
 	  GLYPH g;
 	  int c UNINIT;
@@ -1528,7 +1534,7 @@ #define CONDITIONAL_REASSIGN(cap1, cap2, sym)				\
    available from the initial frame as in batch mode.  */
 
 static void append_glyph (struct it *);
-static void append_composite_glyph (struct it *);
+static void append_composite_glyphs (struct it *);
 static void produce_composite_glyph (struct it *);
 static void append_glyphless_glyph (struct it *, int, const char *);
 static void produce_glyphless_glyph (struct it *, Lisp_Object);
@@ -1775,9 +1781,10 @@ produce_glyphs (struct it *it)
    face.  */
 
 static void
-append_composite_glyph (struct it *it)
+append_composite_glyphs (struct it *it)
 {
-  struct glyph *glyph;
+  struct glyph *glyph, *end;
+  int i;
 
   eassert (it->glyph_row);
   glyph = it->glyph_row->glyphs[it->area] + it->glyph_row->used[it->area];
@@ -1789,62 +1796,72 @@ append_composite_glyph (struct it *it)
     && !it->glyph_row->full_width_p
     && !WINDOW_RIGHTMOST_P (it->w)
     && WINDOW_RIGHT_MARGIN_WIDTH (it->w) == 0;
-  if (glyph < it->glyph_row->glyphs[1 + it->area] - reserve_last)
+  end = it->glyph_row->glyphs[1 + it->area] - reserve_last;
+  if (glyph < end)
     {
       /* If the glyph row is reversed, we need to prepend the glyph
 	 rather than append it.  */
       if (it->glyph_row->reversed_p && it->area == TEXT_AREA)
 	{
 	  struct glyph *g;
+	  int move_by = it->pixel_width;
 
 	  /* Make room for the new glyph.  */
+	  if (move_by > end - glyph)
+	    move_by = end - glyph;
 	  for (g = glyph - 1; g >= it->glyph_row->glyphs[it->area]; g--)
-	    g[1] = *g;
+	    g[move_by] = *g;
 	  glyph = it->glyph_row->glyphs[it->area];
+	  end = glyph + move_by;
 	}
-      glyph->type = COMPOSITE_GLYPH;
-      eassert (it->pixel_width <= SHRT_MAX);
-      glyph->pixel_width = it->pixel_width;
-      glyph->u.cmp.id = it->cmp_it.id;
-      if (it->cmp_it.ch < 0)
-	{
-	  glyph->u.cmp.automatic = 0;
-	  glyph->u.cmp.id = it->cmp_it.id;
-	}
-      else
+
+      eassert(it->pixel_width <= SHRT_MAX);
+      for (i = 0;
+	   i < it->pixel_width && glyph < end;
+	   ++i)
 	{
-	  glyph->u.cmp.automatic = 1;
+	  glyph->type = COMPOSITE_GLYPH;
+	  glyph->pixel_width = 1;
 	  glyph->u.cmp.id = it->cmp_it.id;
-	  glyph->slice.cmp.from = it->cmp_it.from;
-	  glyph->slice.cmp.to = it->cmp_it.to - 1;
-	}
+	  if (it->cmp_it.ch < 0)
+	    {
+	      glyph->u.cmp.automatic = 0;
+	      glyph->u.cmp.id = it->cmp_it.id;
+	    }
+	  else
+	    {
+	      glyph->u.cmp.automatic = 1;
+	      glyph->u.cmp.id = it->cmp_it.id;
+	      glyph->slice.cmp.from = it->cmp_it.from;
+	      glyph->slice.cmp.to = it->cmp_it.to - 1;
+	    }
+	  glyph->avoid_cursor_p = it->avoid_cursor_p;
+	  glyph->multibyte_p = it->multibyte_p;
+	  glyph->frame = it->f;
+	  glyph->face_id = it->face_id;
+	  glyph->padding_p = i > 0;
+	  glyph->charpos = CHARPOS (it->position);
+	  glyph->object = it->object;
+	  if (it->bidi_p)
+	    {
+	      glyph->resolved_level = it->bidi_it.resolved_level;
+	      eassert ((it->bidi_it.type & 7) == it->bidi_it.type);
+	      glyph->bidi_type = it->bidi_it.type;
+	    }
+	  else
+	    {
+	      glyph->resolved_level = 0;
+	      glyph->bidi_type = UNKNOWN_BT;
+	    }
 
-      glyph->avoid_cursor_p = it->avoid_cursor_p;
-      glyph->multibyte_p = it->multibyte_p;
-      glyph->frame = it->f;
-      glyph->face_id = it->face_id;
-      glyph->padding_p = false;
-      glyph->charpos = CHARPOS (it->position);
-      glyph->object = it->object;
-      if (it->bidi_p)
-	{
-	  glyph->resolved_level = it->bidi_it.resolved_level;
-	  eassert ((it->bidi_it.type & 7) == it->bidi_it.type);
-	  glyph->bidi_type = it->bidi_it.type;
+	  ++it->glyph_row->used[it->area];
+	  ++glyph;
 	}
-      else
-	{
-	  glyph->resolved_level = 0;
-	  glyph->bidi_type = UNKNOWN_BT;
-	}
-
-      ++it->glyph_row->used[it->area];
-      ++glyph;
     }
 }
 
 
-/* Produce a composite glyph for iterator IT.  IT->cmp_id is the ID of
+/* Produce composite glyphs for iterator IT.  IT->cmp_id is the ID of
    the composition.  We simply produces components of the composition
    assuming that the terminal has a capability to layout/render it
    correctly.  */
@@ -1865,9 +1882,9 @@ produce_composite_glyph (struct it *it)
       it->pixel_width = composition_gstring_width (gstring, it->cmp_it.from,
 						   it->cmp_it.to, NULL);
     }
-  it->nglyphs = 1;
+  it->nglyphs = it->pixel_width;
   if (it->glyph_row)
-    append_composite_glyph (it);
+    append_composite_glyphs (it);
 }
 
 
-- 
2.53.0