Fix display of truncated R2L lines on a TTY.

 xdisp.c (display_line): Fix prepending of truncation glyphs to R2L rows.
 (insert_left_trunc_glyphs): Support addition of left truncation glyphs
 to R2L rows.

2 files changed, 59 insertions, 15 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index a5548ff16fc..7becf77dde9 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -4,6 +4,9 @@
         (display_line): Use it.
         (extend_face_to_end_of_line): In almost-filled rows, extend only
         if the row is R2L and not continued.
+        (display_line): Fix prepending of truncation glyphs to R2L rows.
+        (insert_left_trunc_glyphs): Support addition of left truncation
+        glyphs to R2L rows.
 
 2010-04-27  Eli Zaretskii  <eliz@gnu.org>
 
diff --git a/src/xdisp.c b/src/xdisp.c
index 45e6b83ec29..6d0683ba566 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -16739,24 +16739,61 @@ insert_left_trunc_glyphs (it)
   produce_special_glyphs (&truncate_it, IT_TRUNCATION);
 
   /* Overwrite glyphs from IT with truncation glyphs.  */
-  from = truncate_it.glyph_row->glyphs[TEXT_AREA];
-  end = from + truncate_it.glyph_row->used[TEXT_AREA];
-  to = it->glyph_row->glyphs[TEXT_AREA];
-  toend = to + it->glyph_row->used[TEXT_AREA];
-
-  while (from < end)
-    *to++ = *from++;
-
-  /* There may be padding glyphs left over.  Overwrite them too.  */
-  while (to < toend && CHAR_GLYPH_PADDING_P (*to))
+  if (!it->glyph_row->reversed_p)
     {
       from = truncate_it.glyph_row->glyphs[TEXT_AREA];
+      end = from + truncate_it.glyph_row->used[TEXT_AREA];
+      to = it->glyph_row->glyphs[TEXT_AREA];
+      toend = to + it->glyph_row->used[TEXT_AREA];
+
       while (from < end)
         *to++ = *from++;
+
+      /* There may be padding glyphs left over.  Overwrite them too.  */
+      while (to < toend && CHAR_GLYPH_PADDING_P (*to))
+        {
+          from = truncate_it.glyph_row->glyphs[TEXT_AREA];
+          while (from < end)
+            *to++ = *from++;
+        }
+
+      if (to > toend)
+        it->glyph_row->used[TEXT_AREA] = to - it->glyph_row->glyphs[TEXT_AREA];
     }
+  else
+    {
+      /* In R2L rows, overwrite the last (rightmost) glyphs, and do
+         that back to front.  */
+      end = truncate_it.glyph_row->glyphs[TEXT_AREA];
+      from = end + truncate_it.glyph_row->used[TEXT_AREA] - 1;
+      toend = it->glyph_row->glyphs[TEXT_AREA];
+      to = toend + it->glyph_row->used[TEXT_AREA] - 1;
+
+      while (from >= end && to >= toend)
+        *to-- = *from--;
+      while (to >= toend && CHAR_GLYPH_PADDING_P (*to))
+        {
+          from =
+            truncate_it.glyph_row->glyphs[TEXT_AREA]
+            + truncate_it.glyph_row->used[TEXT_AREA] - 1;
+          while (from >= end && to >= toend)
+            *to-- = *from--;
+        }
+      if (from >= end)
+        {
+          /* Need to free some room before prepending additional
+             glyphs.  */
+          int move_by = from - end + 1;
+          struct glyph *g0 = it->glyph_row->glyphs[TEXT_AREA];
+          struct glyph *g = g0 + it->glyph_row->used[TEXT_AREA] - 1;
 
-  if (to > toend)
-    it->glyph_row->used[TEXT_AREA] = to - it->glyph_row->glyphs[TEXT_AREA];
+          for ( ; g >= g0; g--)
+            g[move_by] = *g;
+          while (from >= end)
+            *to-- = *from--;
+          it->glyph_row->used[TEXT_AREA] += move_by;
+        }
+    }
 }
 
 
@@ -17938,10 +17975,14 @@ display_line (it)
                   for (i = 0; i < row->used[TEXT_AREA]; i++)
                     if (!CHAR_GLYPH_PADDING_P (row->glyphs[TEXT_AREA][i]))
                       break;
-                  /* Remove padding glyphs at the front of ROW, to
+                  /* Remove any padding glyphs at the front of ROW, to
                      make room for the truncation glyphs we will be
-                     adding below.  */
-                  unproduce_glyphs (it, i);
+                     adding below.  The loop below always inserts at
+                     least one truncation glyph, so also remove the
+                     last glyph added to ROW.  */
+                  unproduce_glyphs (it, i + 1);
+                  /* Adjust i for the loop below.  */
+                  i = row->used[TEXT_AREA] - (i + 1);
                 }
 
               for (n = row->used[TEXT_AREA]; i < n; ++i)