(redisplay_window): If first window line is a continuation line,

recompute the new window start instead of recentering.

1 files changed, 14 insertions, 36 deletions

diff --git a/src/xdisp.c b/src/xdisp.c
index 82f24551f19..151d9980116 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -12777,7 +12777,7 @@ redisplay_window (window, just_this_one_p)
   int rc;
   int centering_position = -1;
   int last_line_misfit = 0;
-  int save_beg_unchanged, save_end_unchanged;
+  int beg_unchanged, end_unchanged;
 
   SET_TEXT_POS (lpoint, PT, PT_BYTE);
   opoint = lpoint;
@@ -12842,8 +12842,8 @@ redisplay_window (window, just_this_one_p)
   set_buffer_internal_1 (XBUFFER (w->buffer));
   SET_TEXT_POS (opoint, PT, PT_BYTE);
 
-  save_beg_unchanged = BEG_UNCHANGED;
-  save_end_unchanged = END_UNCHANGED;
+  beg_unchanged = BEG_UNCHANGED;
+  end_unchanged = END_UNCHANGED;
 
   current_matrix_up_to_date_p
     = (!NILP (w->window_end_valid)
@@ -12968,6 +12968,8 @@ redisplay_window (window, just_this_one_p)
         w->force_start = Qt;
     }
 
+ force_start:
+
   /* Handle case where place to start displaying has been specified,
      unless the specified location is outside the accessible range.  */
   if (!NILP (w->force_start)
@@ -13147,40 +13149,16 @@ redisplay_window (window, just_this_one_p)
          than a simple mouse-click.  */
       if (NILP (w->start_at_line_beg)
           && NILP (do_mouse_tracking)
-          && CHARPOS (startp) > BEGV)
+          && CHARPOS (startp) > BEGV
+          && CHARPOS (startp) > BEG + beg_unchanged
+          && CHARPOS (startp) <= Z - end_unchanged)
         {
-#if 0
-          /* The following code tried to make BEG_UNCHANGED and
-             END_UNCHANGED up to date (similar to try_window_id).
-             Is it important to do so?
-
-             The trouble is that it's a little too strict when it
-             comes to overlays: modify_overlay can call
-             BUF_COMPUTE_UNCHANGED, which alters BUF_BEG_UNCHANGED and
-             BUF_END_UNCHANGED directly without moving the gap.
-
-             This can result in spurious recentering when overlays are
-             altered in the buffer.  So unless it's proven necessary,
-             let's leave this commented out for now. -- cyd.  */
-          if (MODIFF > SAVE_MODIFF
-              || BEG_UNCHANGED + END_UNCHANGED > Z_BYTE)
-            {
-              if (GPT - BEG < BEG_UNCHANGED)
-                BEG_UNCHANGED = GPT - BEG;
-              if (Z - GPT < END_UNCHANGED)
-                END_UNCHANGED = Z - GPT;
-            }
-#endif
-
-          if (CHARPOS (startp) > BEG + save_beg_unchanged
-              && CHARPOS (startp) <= Z - save_end_unchanged)
-            {
-              /* There doesn't seems to be a simple way to find a new
-                 window start that is near the old window start, so
-                 we just recenter.  */
-              goto recenter;
-            }
-        }
+          w->force_start = Qt;
+          if (XMARKER (w->start)->buffer == current_buffer)
+            compute_window_start_on_continuation_line (w);
+          SET_TEXT_POS_FROM_MARKER (startp, w->start);
+          goto force_start;
+        }
 
 #if GLYPH_DEBUG
       debug_method_add (w, "same window start");