(try_cursor_movement): Exclude header line from scroll

margin at top of window.
(try_window_reusing_current_matrix): Calculate proper cursor position
after scrolling up with non-zero scroll margin, as the old cursor
position corresponds to value of PT before executing this command.
(try_window_id): Consider scroll margin at bottom of window too;
otherwise we fail to scroll when hl-line-mode is enabled.

1 files changed, 35 insertions, 9 deletions

diff --git a/src/xdisp.c b/src/xdisp.c
index 447f4dfbf79..cd712ac7485 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -11267,7 +11267,7 @@ try_cursor_movement (window, startp, scroll_step)
       && (FRAME_WINDOW_P (f)
           || !overlay_arrow_in_current_buffer_p ()))
     {
-      int this_scroll_margin;
+      int this_scroll_margin, top_scroll_margin;
       struct glyph_row *row = NULL;
 
 #if GLYPH_DEBUG
@@ -11280,6 +11280,10 @@ try_cursor_movement (window, startp, scroll_step)
       this_scroll_margin = min (this_scroll_margin, WINDOW_TOTAL_LINES (w) / 4);
       this_scroll_margin *= FRAME_LINE_HEIGHT (f);
 
+      top_scroll_margin = this_scroll_margin;
+      if (WINDOW_WANTS_HEADER_LINE_P (w))
+        top_scroll_margin += CURRENT_HEADER_LINE_HEIGHT (w);
+
       /* Start with the row the cursor was displayed during the last
          not paused redisplay.  Give up if that row is not valid.  */
       if (w->last_cursor.vpos < 0
@@ -11340,7 +11344,7 @@ try_cursor_movement (window, startp, scroll_step)
                      && (MATRIX_ROW_START_CHARPOS (row) > PT
                          || (MATRIX_ROW_START_CHARPOS (row) == PT
                              && MATRIX_ROW_STARTS_IN_MIDDLE_OF_CHAR_P (row)))
-                     && (row->y > this_scroll_margin
+                     && (row->y > top_scroll_margin
                          || CHARPOS (startp) == BEGV))
                 {
                   xassert (row->enabled_p);
@@ -11368,7 +11372,7 @@ try_cursor_movement (window, startp, scroll_step)
                 ++row;
 
               /* If within the scroll margin, scroll.  */
-              if (row->y < this_scroll_margin
+              if (row->y < top_scroll_margin
                   && CHARPOS (startp) != BEGV)
                 scroll_p = 1;
             }
@@ -12538,9 +12542,8 @@ try_window_reusing_current_matrix (w)
          position.  */
       if (pt_row)
         {
-          w->cursor.vpos -= MATRIX_ROW_VPOS (first_reusable_row,
-                                             w->current_matrix);
-          w->cursor.y -= first_reusable_row->y;
+          w->cursor.vpos -= nrows_scrolled;
+          w->cursor.y -= first_reusable_row->y - start_row->y;
         }
 
       /* Scroll the display.  */
@@ -12585,6 +12588,29 @@ try_window_reusing_current_matrix (w)
       for (row -= nrows_scrolled; row < bottom_row; ++row)
         row->enabled_p = 0;
 
+      /* Point may have moved to a different line, so we cannot assume that
+         the previous cursor position is valid; locate the correct row.  */
+      if (pt_row)
+        {
+          for (row = MATRIX_ROW (w->current_matrix, w->cursor.vpos);
+               row < bottom_row && PT >= MATRIX_ROW_END_CHARPOS (row);
+               row++)
+            {
+              w->cursor.vpos++;
+              w->cursor.y = row->y;
+            }
+          if (row < bottom_row)
+            {
+              struct glyph *glyph = row->glyphs[TEXT_AREA] + w->cursor.hpos;
+              while (glyph->charpos < PT)
+                {
+                  w->cursor.hpos++;
+                  w->cursor.x += glyph->pixel_width;
+                  glyph++;
+                }
+            }
+        }
+
       /* Adjust window end.  A null value of last_text_row means that
          the window end is in reused rows which in turn means that
          only its vpos can have changed.  */
@@ -13368,9 +13394,9 @@ try_window_id (w)
 
     if ((w->cursor.y < this_scroll_margin
          && CHARPOS (start) > BEGV)
-        /* Don't take scroll margin into account at the bottom because
-           old redisplay didn't do it either.  */
-        || w->cursor.y + cursor_height > it.last_visible_y)
+        /* Old redisplay didn't take scroll margin into account at the bottom,
+           but then global-hl-line-mode doesn't scroll.  KFS 2004-06-14 */
+        || w->cursor.y + cursor_height + this_scroll_margin > it.last_visible_y)
       {
         w->cursor.vpos = -1;
         clear_glyph_matrix (w->desired_matrix);