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(redisplay_window) <force-start case>:

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If point is on semi-visible last line, reposition
it at previous line.
This commit is contained in:
Richard M. Stallman 2002-09-01 13:43:38 +00:00
parent dfe15ea33e
commit b60c965364
1 changed files with 32 additions and 44 deletions
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76
src/xdisp.c
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@ -8963,6 +8963,8 @@ redisplay_internal (preserve_echo_area)
judge_scroll_bars_hook (f);
/* If fonts changed, display again. */
/* ??? rms: I suspect it is a mistake to jump all the way
back to retry here. It should just retry this frame. */
if (fonts_changed_p)
goto retry;
@ -10098,7 +10100,11 @@ try_cursor_movement (window, startp, scroll_step)
/* Redisplay leaf window WINDOW. JUST_THIS_ONE_P non-zero means only
selected_window is redisplayed. */
selected_window is redisplayed.
We can return without actually redisplaying the window if
fonts_changed_p is nonzero. In that case, redisplay_internal will
retry. */
static void
redisplay_window (window, just_this_one_p)
@ -10305,6 +10311,9 @@ redisplay_window (window, just_this_one_p)
if (!NILP (w->force_start)
|| w->frozen_window_start_p)
{
/* We set this later on if we have to adjust point. */
int new_vpos = -1;
w->force_start = Qnil;
w->vscroll = 0;
w->window_end_valid = Qnil;
@ -10341,7 +10350,7 @@ redisplay_window (window, just_this_one_p)
{
w->force_start = Qt;
clear_glyph_matrix (w->desired_matrix);
goto finish_scroll_bars;
goto need_larger_matrices;
}
if (w->cursor.vpos < 0 && !w->frozen_window_start_p)
@ -10349,12 +10358,24 @@ redisplay_window (window, just_this_one_p)
/* If point does not appear, try to move point so it does
appear. The desired matrix has been built above, so we
can use it here. */
int window_height;
new_vpos = window_box_height (w) / 2;
}
if (!make_cursor_line_fully_visible (w))
{
/* Point does appear, but on a line partly visible at end of window.
Move it back to a fully-visible line. */
new_vpos = window_box_height (w);
}
/* If we need to move point for either of the above reasons,
now actually do it. */
if (new_vpos >= 0)
{
struct glyph_row *row;
window_height = window_box_height (w) / 2;
row = MATRIX_FIRST_TEXT_ROW (w->desired_matrix);
while (MATRIX_ROW_BOTTOM_Y (row) < window_height)
while (MATRIX_ROW_BOTTOM_Y (row) < new_vpos)
++row;
TEMP_SET_PT_BOTH (MATRIX_ROW_START_CHARPOS (row),
@ -10378,45 +10399,6 @@ redisplay_window (window, just_this_one_p)
}
}
if (!make_cursor_line_fully_visible (w))
{
/* CVS rev. 1.761 had changed this to ``goto try_to_scroll''.
The intention of the fix -- AFAIU -- was to ensure that
the cursor didn't end up on a partially visible last (or
first?) line when scrolling.
But that change causes havoc when scrolling backwards and
a partially visible first (or last?) line is present when
we reach the top of the buffer. In effect, the text
already in the window is repeated (each line is appended
to the same or another lines in the window)...
I changed it back to ``goto need_larger_matrices'' which
in effect mean that we don't go through `try_scrolling'
when the cursor is already at the first line of the buffer,
and there is really only a few pixels [rather than lines]
to scroll backwards. I guess move_it_by_lines etc. really
isn't the right device for doing that, ref. the code in
make_cursor_line_fully_visible which was also disabled by
CVS rev. 1.761.
But how do we know that we are already on the top line of
the window showing the first line in the buffer, so that
scrolling really wont help here?
I cannot find a simple fix for this (I tried various
approaches), but I prefer to an occasional partial line
rather than the visual messup, so I reverted this part of
the fix.
Someone will need to look into this when time allows.
-- 2002-08-22, Kim F. Storm */
goto need_larger_matrices;
}
#if GLYPH_DEBUG
debug_method_add (w, "forced window start");
#endif
@ -10435,8 +10417,10 @@ redisplay_window (window, just_this_one_p)
case CURSOR_MOVEMENT_SUCCESS:
goto done;
#if 0 /* try_cursor_movement never returns this value. */
case CURSOR_MOVEMENT_NEED_LARGER_MATRICES:
goto need_larger_matrices;
#endif
case CURSOR_MOVEMENT_MUST_SCROLL:
goto try_to_scroll;
@ -10765,6 +10749,10 @@ redisplay_window (window, just_this_one_p)
#endif
}
/* We go to this label, with fonts_changed_p nonzero,
if it is necessary to try again using larger glyph matrices.
We have to redeem the scroll bar even in this case,
because the loop in redisplay_internal expects that. */
need_larger_matrices:
;
finish_scroll_bars: