(Fpos_visible_in_window_p): Adapt to new pos_visible_p.

Return row height and row number for partially visible rows.
Modify return value to a 2 element list for fully visible rows
and 6 for partially visible row.
(window_scroll_pixel_based): Use pos_visible_p directly instead of
Fpos_visible_in_window_p.  Fix auto vscrolling for partially visible lines.
Only vscroll backwards if already vscrolled forwards.  Unconditionally
vscroll forwards if PT is first (and only) line.  Set new window start
instead of scrolling at start/end of tall line.

1 files changed, 65 insertions, 27 deletions

diff --git a/src/window.c b/src/window.c
index a0a8b351a02..ee2faf09ca6 100644
--- a/src/window.c
+++ b/src/window.c
@@ -336,10 +336,12 @@ If POS is only out of view because of horizontal scrolling, return non-nil.
 POS defaults to point in WINDOW; WINDOW defaults to the selected window.
 
 If POS is visible, return t if PARTIALLY is nil; if PARTIALLY is non-nil,
-return value is a list (X Y PARTIAL) where X and Y are the pixel coordinates
-relative to the top left corner of the window. PARTIAL is nil if the character
-after POS is fully visible; otherwise it is a cons (RTOP . RBOT) where RTOP
-and RBOT are the number of pixels invisible at the top and bottom of the row.  */)
+return value is a list of 2 or 6 elements (X Y [RTOP RBOT ROWH VPOS]),
+where X and Y are the pixel coordinates relative to the top left corner
+of the window.  The remaining elements are omitted if the character after
+POS is fully visible; otherwise, RTOP and RBOT are the number of pixels
+invisible at the top and bottom of the row, ROWH is the height of the display
+row, and VPOS is the row number (0-based) containing POS.  */)
      (pos, window, partially)
      Lisp_Object pos, window, partially;
 {
@@ -348,7 +350,7 @@ and RBOT are the number of pixels invisible at the top and bottom of the row.  *
   register struct buffer *buf;
   struct text_pos top;
   Lisp_Object in_window = Qnil;
-  int rtop, rbot, fully_p = 1;
+  int rtop, rbot, rowh, vpos, fully_p = 1;
   int x, y;
 
   w = decode_window (window);
@@ -371,17 +373,20 @@ and RBOT are the number of pixels invisible at the top and bottom of the row.  *
       && posint <= BUF_ZV (buf)
       && CHARPOS (top) >= BUF_BEGV (buf)
       && CHARPOS (top) <= BUF_ZV (buf)
-      && pos_visible_p (w, posint, &x, &y, &rtop, &rbot, NILP (partially))
+      && pos_visible_p (w, posint, &x, &y, &rtop, &rbot, &rowh, &vpos)
       && (fully_p = !rtop && !rbot, (!NILP (partially) || fully_p)))
     in_window = Qt;
 
   if (!NILP (in_window) && !NILP (partially))
-    in_window = Fcons (make_number (x),
-                       Fcons (make_number (y),
-                              Fcons ((fully_p ? Qnil
-                                     : Fcons (make_number (rtop),
-                                              make_number (rbot))),
-                                     Qnil)));
+    {
+      Lisp_Object part = Qnil;
+      if (!fully_p)
+        part = list4 (make_number (rtop), make_number (rbot),
+                        make_number (rowh), make_number (vpos));
+      in_window = Fcons (make_number (x),
+                         Fcons (make_number (y), part));
+    }
+
   return in_window;
 }
 
@@ -4818,10 +4823,10 @@ window_scroll_pixel_based (window, n, whole, noerror)
   struct it it;
   struct window *w = XWINDOW (window);
   struct text_pos start;
-  Lisp_Object tem;
   int this_scroll_margin;
   /* True if we fiddled the window vscroll field without really scrolling.   */
   int vscrolled = 0;
+  int x, y, rtop, rbot, rowh, vpos;
 
   SET_TEXT_POS_FROM_MARKER (start, w->start);
 
@@ -4829,8 +4834,8 @@ window_scroll_pixel_based (window, n, whole, noerror)
      the screen.  Allow PT to be partially visible, otherwise
      something like (scroll-down 1) with PT in the line before
      the partially visible one would recenter. */
-  tem = Fpos_visible_in_window_p (make_number (PT), window, Qt);
-  if (NILP (tem))
+
+  if (!pos_visible_p (w, PT, &x, &y, &rtop, &rbot, &rowh, &vpos))
     {
       /* Move backward half the height of the window.  Performance note:
          vmotion used here is about 10% faster, but would give wrong
@@ -4855,7 +4860,7 @@ window_scroll_pixel_based (window, n, whole, noerror)
     }
   else if (auto_window_vscroll_p)
     {
-      if (tem = XCAR (XCDR (XCDR (tem))), CONSP (tem))
+      if (rtop || rbot)         /* partially visible */
         {
           int px;
           int dy = WINDOW_FRAME_LINE_HEIGHT (w);
@@ -4865,19 +4870,52 @@ window_scroll_pixel_based (window, n, whole, noerror)
                       dy);
           dy *= n;
 
-          if (n < 0 && (px = XINT (XCAR (tem))) > 0)
+          if (n < 0)
             {
-              px = max (0, -w->vscroll - min (px, -dy));
-              Fset_window_vscroll (window, make_number (px), Qt);
-              return;
+              /* Only vscroll backwards if already vscrolled forwards.  */
+              if (w->vscroll < 0 && rtop > 0)
+                {
+                  px = max (0, -w->vscroll - min (rtop, -dy));
+                  Fset_window_vscroll (window, make_number (px), Qt);
+                  return;
+                }
             }
-          if (n > 0 && (px = XINT (XCDR (tem))) > 0)
+          if (n > 0)
             {
-              px = max (0, -w->vscroll + min (px, dy));
-              Fset_window_vscroll (window, make_number (px), Qt);
-              return;
+              /* Do vscroll if already vscrolled or only display line.  */
+              if (rbot > 0 && (w->vscroll < 0 || vpos == 0))
+                {
+                  px = max (0, -w->vscroll + min (rbot, dy));
+                  Fset_window_vscroll (window, make_number (px), Qt);
+                  return;
+                }
+
+              /* Maybe modify window start instead of scrolling.  */
+              if (rbot > 0 || w->vscroll < 0)
+                {
+                  int spos;
+
+                  Fset_window_vscroll (window, make_number (0), Qt);
+                  /* If there are other text lines above the current row,
+                     move window start to current row.  Else to next row. */
+                  if (rbot > 0)
+                    spos = XINT (Fline_beginning_position (Qnil));
+                  else
+                    spos = min (XINT (Fline_end_position (Qnil)) + 1, ZV);
+                  set_marker_restricted (w->start, make_number (spos),
+                                         w->buffer);
+                  w->start_at_line_beg = Qt;
+                  w->update_mode_line = Qt;
+                  XSETFASTINT (w->last_modified, 0);
+                  XSETFASTINT (w->last_overlay_modified, 0);
+                  /* Set force_start so that redisplay_window will run the
+                     window-scroll-functions.  */
+                  w->force_start = Qt;
+                  return;
+                }
             }
         }
+      /* Cancel previous vscroll.  */
       Fset_window_vscroll (window, make_number (0), Qt);
     }
 
@@ -4918,7 +4956,7 @@ window_scroll_pixel_based (window, n, whole, noerror)
       if (dy <= 0)
         {
           move_it_vertically_backward (&it, -dy);
-          /* Ensure we actually does move, e.g. in case we are currently
+          /* Ensure we actually do move, e.g. in case we are currently
              looking at an image that is taller that the window height.  */
           while (start_pos == IT_CHARPOS (it)
                  && start_pos > BEGV)
@@ -4928,7 +4966,7 @@ window_scroll_pixel_based (window, n, whole, noerror)
         {
           move_it_to (&it, ZV, -1, it.current_y + dy, -1,
                       MOVE_TO_POS | MOVE_TO_Y);
-          /* Ensure we actually does move, e.g. in case we are currently
+          /* Ensure we actually do move, e.g. in case we are currently
              looking at an image that is taller that the window height.  */
           while (start_pos == IT_CHARPOS (it)
                  && start_pos < ZV)
@@ -6656,7 +6694,7 @@ display marginal areas and the text area.  */)
     CHECK_NATNUM (left_width);
   if (!NILP (right_width))
     CHECK_NATNUM (right_width);
- 
+
   /* Do nothing on a tty.  */
   if (FRAME_WINDOW_P (WINDOW_XFRAME (w))
       && (!EQ (w->left_fringe_width, left_width)