Commit 9317a85d authored by Richard M. Stallman's avatar Richard M. Stallman

(scroll_preserve_screen_position): New variable.

(keys_of_window): Set up Lisp var.
(window_scroll): If scroll_preserve_screen_position is 0,
behave the old way (advancing point the minimum distance).
parent 50b3531c
......@@ -111,8 +111,14 @@ static int sequence_number;
/* Nonzero after init_window_once has finished. */
static int window_initialized;
/* Nonzero means scroll commands try to put point
at the same screen height as previously. */
static int scroll_preserve_screen_position;
#define min(a, b) ((a) < (b) ? (a) : (b))
extern int scroll_margin;
extern Lisp_Object Qwindow_scroll_functions, Vwindow_scroll_functions;
DEFUN ("windowp", Fwindowp, Swindowp, 1, 1, 0,
......@@ -2638,8 +2644,7 @@ window_internal_width (w)
/* Scroll contents of window WINDOW up N lines.
If WHOLE is nonzero, it means we wanted to scroll
by entire screenfuls. */
If WHOLE is nonzero, it means scroll N screenfuls instead. */
static void
window_scroll (window, n, whole, noerror)
......@@ -2693,8 +2698,6 @@ window_scroll (window, n, whole, noerror)
if (pos < ZV)
{
extern int scroll_margin;
int this_scroll_margin = scroll_margin;
/* Don't use a scroll margin that is negative or too large. */
......@@ -2713,7 +2716,7 @@ window_scroll (window, n, whole, noerror)
the window-scroll-functions. */
w->force_start = Qt;
if (whole)
if (whole && scroll_preserve_screen_position)
{
SET_PT (pos);
Fvertical_motion (make_number (original_vpos), window);
......@@ -2735,11 +2738,13 @@ window_scroll (window, n, whole, noerror)
if (top_margin <= opoint)
SET_PT (opoint);
else
else if (scroll_preserve_screen_position)
{
SET_PT (pos);
Fvertical_motion (make_number (original_vpos), window);
}
else
SET_PT (pos);
}
else if (n < 0)
{
......@@ -2758,8 +2763,13 @@ window_scroll (window, n, whole, noerror)
SET_PT (opoint);
else
{
SET_PT (pos);
Fvertical_motion (make_number (original_vpos), window);
if (scroll_preserve_screen_position)
{
SET_PT (pos);
Fvertical_motion (make_number (original_vpos), window);
}
else
Fvertical_motion (make_number (-1), window);
}
}
}
......@@ -3644,6 +3654,11 @@ If there is only one window, it is split regardless of this value.");
"*Delete any window less than this wide.");
window_min_width = 10;
DEFVAR_BOOL ("scroll-preserve-screen-position",
&scroll_preserve_screen_position,
"*Nonzero means scroll commands move point to keep its screen line unchanged.");
scroll_preserve_screen_position = 0;
defsubr (&Sselected_window);
defsubr (&Sminibuffer_window);
defsubr (&Swindow_minibuffer_p);
......
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