(redisplay_window): Update STARTP_BYTE alongside with

STARTP.  New variable scroll_margin_bytepos, to parallel
scroll_margin_pos.  Fix arguments of pos_tab_offset to agree with
the first argument of compute_motion.

diff --git a/src/xdisp.c b/src/xdisp.c
index 2ac8e7d45b497e715ae69615323491c11d3cfe0f..6df80a40560f9327985dc6c7e30fd41860945ba4 100644 (file)
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -1952,6 +1952,7 @@ redisplay_window (window, just_this_one, preserve_echo_area)
              run_hook_with_args_2 (Qwindow_scroll_functions, window,
                                    make_number (startp));
              startp = marker_position (w->start);
+             startp_byte = marker_byte_position (w->start);
            }
        }
       XSETFASTINT (w->last_modified, 0);
@@ -2203,7 +2204,7 @@ redisplay_window (window, just_this_one, preserve_echo_area)
       && startp >= BEGV && startp <= ZV)
     {
       int this_scroll_margin = scroll_margin;
-      int scroll_margin_pos;
+      int scroll_margin_pos, scroll_margin_bytepos;
 
       /* Don't use a scroll margin that is negative or too large.  */
       if (this_scroll_margin < 0)
@@ -2217,14 +2218,19 @@ redisplay_window (window, just_this_one, preserve_echo_area)
        {
          pos = *vmotion (scroll_margin_pos, -this_scroll_margin, w);
          scroll_margin_pos = pos.bufpos;
+         scroll_margin_bytepos = pos.bytepos;
        }
+      else
+       scroll_margin_bytepos = CHAR_TO_BYTE (scroll_margin_pos);
+
       if (PT >= scroll_margin_pos)
        {
          struct position pos;
          pos = *compute_motion (scroll_margin_pos, 0, 0, 0,
                                 PT, XFASTINT (w->height), 0,
                                 XFASTINT (w->width), XFASTINT (w->hscroll),
-                                pos_tab_offset (w, startp, startp_byte),
+                                pos_tab_offset (w, scroll_margin_pos,
+                                                scroll_margin_bytepos),
                                 w);
          if (pos.vpos > scroll_conservatively)
            goto scroll_fail_1;
@@ -2263,7 +2269,7 @@ redisplay_window (window, just_this_one, preserve_echo_area)
          pos = *compute_motion (PT, 0, 0, 0,
                                 scroll_margin_pos, XFASTINT (w->height), 0,
                                 XFASTINT (w->width), XFASTINT (w->hscroll),
-                                pos_tab_offset (w, startp, startp_byte),
+                                pos_tab_offset (w, PT, PT_BYTE),
                                 w);
          if (pos.vpos > scroll_conservatively)
            goto scroll_fail_1;