From: Eli Zaretskii <eliz@gnu.org>
Date: Sat, 6 Aug 2022 13:24:34 +0000 (+0300)
Subject: Fix C-n/C-p inside bidirectional text
X-Git-Tag: emacs-29.0.90~1447^2~372
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=55c25e73d46685e4b4423b13b0d3287fee170386;p=emacs.git

Fix C-n/C-p inside bidirectional text

* src/xdisp.c (move_it_by_lines, try_cursor_movement): Handle
glyph rows whose direction of increasing buffer positions is
reverse of the normal: going down in the window makes buffer
positions higher.
* src/indent.c (Fvertical_motion): When looking for the last glyph
row occupied by point, take into account the bidi iteration
direction.
---

diff --git a/src/indent.c b/src/indent.c
index fd2e7636656..d2dfaee254e 100644
--- a/src/indent.c
+++ b/src/indent.c
@@ -2345,7 +2345,15 @@ whether or not it is currently displayed in some window.  */)
 	     last line that it occupies.  */
 	  if (it_start < ZV)
 	    {
-	      while (IT_CHARPOS (it) <= it_start)
+	      if ((it.bidi_it.scan_dir > 0)
+		  ? IT_CHARPOS (it) < it_start
+		  : IT_CHARPOS (it) > it_start)
+		{
+		  it.vpos = 0;
+		  it.current_y = 0;
+		  move_it_by_lines (&it, 1);
+		}
+	      while (IT_CHARPOS (it) == it_start)
 		{
 		  it.vpos = 0;
 		  it.current_y = 0;
diff --git a/src/xdisp.c b/src/xdisp.c
index 3ca0022a6d3..c756e7f04f6 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -10956,15 +10956,21 @@ move_it_by_lines (struct it *it, ptrdiff_t dvpos)
       int nchars_per_row
 	= (it->last_visible_x - it->first_visible_x) / FRAME_COLUMN_WIDTH (it->f);
       bool hit_pos_limit = false;
+      bool reverse_rows = false;
       ptrdiff_t pos_limit;
 
       /* Start at the beginning of the screen line containing IT's
 	 position.  This may actually move vertically backwards,
          in case of overlays, so adjust dvpos accordingly.  */
       dvpos += it->vpos;
+      start_charpos = IT_CHARPOS (*it);
       move_it_vertically_backward (it, 0);
       dvpos -= it->vpos;
 
+      /* Do we have glyph rows whose positions _increase_ as we go up?  */
+      if (IT_CHARPOS (*it) > start_charpos)
+	reverse_rows = true;
+
       /* Go back -DVPOS buffer lines, but no farther than -DVPOS full
 	 screen lines, and reseat the iterator there.  */
       start_charpos = IT_CHARPOS (*it);
@@ -11015,7 +11021,8 @@ move_it_by_lines (struct it *it, ptrdiff_t dvpos)
 	  SAVE_IT (it2, *it, it2data);
 	  move_it_to (it, -1, -1, -1, it->vpos + delta, MOVE_TO_VPOS);
 	  /* Move back again if we got too far ahead.  */
-	  if (IT_CHARPOS (*it) >= start_charpos)
+	  if ((IT_CHARPOS (*it) >= start_charpos && !reverse_rows)
+	      || (IT_CHARPOS (*it) <= start_charpos && reverse_rows))
 	    RESTORE_IT (it, &it2, it2data);
 	  else
 	    bidi_unshelve_cache (it2data, true);
@@ -18837,6 +18844,8 @@ try_cursor_movement (Lisp_Object window, struct text_pos startp,
 	    {
 	      /* Cursor has to be moved backward.  Note that PT >=
 		 CHARPOS (startp) because of the outer if-statement.  */
+	      struct glyph_row *row0 = row;
+
 	      while (!row->mode_line_p
 		     && (MATRIX_ROW_START_CHARPOS (row) > PT
 			 || (MATRIX_ROW_START_CHARPOS (row) == PT
@@ -18851,6 +18860,23 @@ try_cursor_movement (Lisp_Object window, struct text_pos startp,
 		  --row;
 		}
 
+	      /* With bidi-reordered rows we can have buffer positions
+		 _decrease_ when going down by rows.  If we haven't
+		 found our row in the loop above, give it another try
+		 now going in the other direction from the original row.  */
+	      if (!(MATRIX_ROW_START_CHARPOS (row) <= PT
+		    && PT <= MATRIX_ROW_END_CHARPOS (row))
+		  && row0->continued_p)
+		{
+		  row = row0;
+		  while (MATRIX_ROW_START_CHARPOS (row) > PT
+			 && MATRIX_ROW_BOTTOM_Y (row) < last_y)
+		    {
+		      eassert (row->enabled_p);
+		      ++row;
+		    }
+		}
+
 	      /* Consider the following case: Window starts at BEGV,
 		 there is invisible, intangible text at BEGV, so that
 		 display starts at some point START > BEGV.  It can
@@ -18874,9 +18900,16 @@ try_cursor_movement (Lisp_Object window, struct text_pos startp,
 		     && !cursor_row_p (row))
 		++row;
 
-	      /* If within the scroll margin, scroll.  */
-	      if (row->y < top_scroll_margin
-		  && CHARPOS (startp) != BEGV)
+	      /* If within the scroll margin, either the top one or
+		 the bottom one, scroll.  */
+	      if ((row->y < top_scroll_margin
+		   && CHARPOS (startp) != BEGV)
+		  || MATRIX_ROW_BOTTOM_Y (row) > last_y
+		  || PT > MATRIX_ROW_END_CHARPOS (row)
+		  || (MATRIX_ROW_BOTTOM_Y (row) == last_y
+		      && PT == MATRIX_ROW_END_CHARPOS (row)
+		      && !row->ends_at_zv_p
+		      && !MATRIX_ROW_ENDS_IN_MIDDLE_OF_CHAR_P (row)))
 		scroll_p = true;
 	    }
 	  else