>From a3f75f63fed67e4a63eb1412d910c9e66c4cc2b8 Mon Sep 17 00:00:00 2001
From: Alan Third <alan@idiocy.org>
Date: Sun, 17 Apr 2022 21:15:05 +0100
Subject: [PATCH] Fix glyphless glyph display on NS (bug#54970)

* src/nsterm.m (ns_draw_glyphless_glyph_string_foreground): New
function.
(ns_draw_glyph_string): Use the new function.
---
 src/nsterm.m | 79 ++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 76 insertions(+), 3 deletions(-)

diff --git a/src/nsterm.m b/src/nsterm.m
index 550f29212e..18e219949b 100644
--- a/src/nsterm.m
+++ b/src/nsterm.m
@@ -3945,6 +3945,81 @@ Function modeled after x_draw_glyph_string_box ().
     }
 }
 
+/* Draw the foreground of glyph string S for glyphless characters.  */
+static void
+ns_draw_glyphless_glyph_string_foreground (struct glyph_string *s)
+{
+  struct glyph *glyph = s->first_glyph;
+  unsigned char2b[8];
+  int x, i, j;
+
+  /* If first glyph of S has a left box line, start drawing the text
+     of S to the right of that box line.  */
+  if (s->face && s->face->box != FACE_NO_BOX
+      && s->first_glyph->left_box_line_p)
+    x = s->x + max (s->face->box_vertical_line_width, 0);
+  else
+    x = s->x;
+
+  s->char2b = char2b;
+
+  for (i = 0; i < s->nchars; i++, glyph++)
+    {
+      char buf[7];
+      char *str = NULL;
+      int len = glyph->u.glyphless.len;
+
+      if (glyph->u.glyphless.method == GLYPHLESS_DISPLAY_ACRONYM)
+	{
+	  if (len > 0
+	      && CHAR_TABLE_P (Vglyphless_char_display)
+	      && (CHAR_TABLE_EXTRA_SLOTS (XCHAR_TABLE (Vglyphless_char_display))
+		  >= 1))
+	    {
+	      Lisp_Object acronym
+		= (! glyph->u.glyphless.for_no_font
+		   ? CHAR_TABLE_REF (Vglyphless_char_display,
+				     glyph->u.glyphless.ch)
+		   : XCHAR_TABLE (Vglyphless_char_display)->extras[0]);
+	      if (STRINGP (acronym))
+		str = SSDATA (acronym);
+	    }
+	}
+      else if (glyph->u.glyphless.method == GLYPHLESS_DISPLAY_HEX_CODE)
+	{
+	  unsigned int ch = glyph->u.glyphless.ch;
+	  eassume (ch <= MAX_CHAR);
+	  sprintf (buf, "%0*X", ch < 0x10000 ? 4 : 6, ch);
+	  str = buf;
+	}
+
+      if (str)
+	{
+	  int upper_len = (len + 1) / 2;
+
+	  /* It is assured that all LEN characters in STR is ASCII.  */
+	  for (j = 0; j < len; j++)
+            char2b[j] = s->font->driver->encode_char (s->font, str[j]) & 0xFFFF;
+	  s->font->driver->draw (s, 0, upper_len,
+				 x + glyph->slice.glyphless.upper_xoff,
+				 s->ybase + glyph->slice.glyphless.upper_yoff,
+				 false);
+	  s->font->driver->draw (s, upper_len, len,
+				 x + glyph->slice.glyphless.lower_xoff,
+				 s->ybase + glyph->slice.glyphless.lower_yoff,
+				 false);
+	}
+      if (glyph->u.glyphless.method != GLYPHLESS_DISPLAY_THIN_SPACE)
+        ns_draw_box (NSMakeRect (x, s->ybase - glyph->ascent,
+                                 glyph->pixel_width - 1,
+                                 glyph->ascent + glyph->descent - 1),
+                     1, 1,
+                     [NSColor colorWithUnsignedLong:NS_FACE_FOREGROUND (s->face)],
+                     YES, YES);
+      x += glyph->pixel_width;
+   }
+}
+
 static void
 ns_draw_glyph_string (struct glyph_string *s)
 /* --------------------------------------------------------------------------
@@ -4058,9 +4133,7 @@ Function modeled after x_draw_glyph_string_box ().
       else
         ns_maybe_dumpglyphs_background
           (s, s->first_glyph->type == COMPOSITE_GLYPH);
-      /* ... */
-      /* Not yet implemented.  */
-      /* ... */
+      ns_draw_glyphless_glyph_string_foreground (s);
       break;
 
     default:
-- 
2.35.1