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Commit 3d16ffb3 authored by Alan Mackenzie's avatar Alan Mackenzie
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Fix follow-scroll-up/down, making them replacements for scroll-up/down. 

1. Allow point to move between follow windows in scroll operations.
2. Fix bug where `right-char' just before EOB caused spurious scrolling,
when EOB was isolated in the last follow window.

lisp/follow.el (follow-fixed-window): New variable.
(follow-get-scrolled-point): New function.
(follow-scrol-up, follow-scroll-down): Add autoload cookies.
Reformulate
the code.  Put `scroll-command' properties on the functions.  Correct
minor errors in ...-down's doc string and code.
(follow-calc-win-end): Amend incomplete doc string.  Use
`pos-visible-in-window-p' to check whether EOB is in the window.
(follow-estimate-first-window-start): Correct an off-by-1 error.
(follow-adjust-window): Add handling for explicit scrolling operations.
parent 2e775b43
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Showing with 224 additions and 168 deletions
lisp/follow.el
View file @ 3d16ffb3
......@@ -347,6 +347,9 @@ Used by `follow-window-size-change'.")
(defvar follow-windows-start-end-cache nil
"Cache used by `follow-window-start-end'.")
(defvar follow-fixed-window nil
"If non-nil, the current window must not be scrolled.
This is typically set by explicit scrolling commands.")
;;; Debug messages
;; This inline function must be as small as possible!
......@@ -439,6 +442,54 @@ Keys specific to Follow mode:
;;; Scroll
(defun follow-get-scrolled-point (dest windows)
"Calculate the correct value for point after a scrolling operation.
DEST is our default position, typically where point was before the scroll.
If `scroll-preserve-screen-position' is non-nil and active, DEST will be
in the same screen position as before the scroll. WINDOWS is the list of
windows in the follow chain.
This function attempts to duplicate the point placing from
`window_scroll_line_based' in the Emacs core source window.c.
Return the new position."
(if (and scroll-preserve-screen-position
(get this-command 'scroll-command))
dest
(let ((dest-column
(save-excursion
(goto-char dest)
(- (current-column)
(progn (vertical-motion 0) (current-column)))))
(limit0
(with-selected-window (car windows)
(save-excursion
(goto-char (window-start))
(vertical-motion 0)
(point))))
(limitn
(with-selected-window (car (reverse windows))
(save-excursion
(goto-char (window-end nil t))
(if (pos-visible-in-window-p)
(point) ; i.e. (point-max)
(1- (point)))))))
(cond
((< dest limit0)
(with-selected-window (car windows)
(save-excursion
(goto-char limit0)
(vertical-motion (cons dest-column 0))
(point))))
((> dest limitn)
(with-selected-window (car (reverse windows))
(save-excursion
(goto-char limitn)
(vertical-motion (cons dest-column 0))
(point))))
(t dest)))))
;; `scroll-up' and `-down', but for windows in Follow mode.
;;
;; Almost like the real thing, except when the cursor ends up outside
......@@ -454,6 +505,7 @@ Keys specific to Follow mode:
;; position... (This would also be corrected if we would have had a
;; good redisplay abstraction.)
;;;###autoload
(defun follow-scroll-up (&optional arg)
"Scroll text in a Follow mode window chain up.
......@@ -467,22 +519,26 @@ Works like `scroll-up' when not in Follow mode."
(interactive "P")
(cond ((not follow-mode)
(scroll-up arg))
(arg
(save-excursion (scroll-up arg))
(setq follow-internal-force-redisplay t))
((eq arg '-)
(follow-scroll-down))
(t
(let* ((windows (follow-all-followers))
(end (window-end (car (reverse windows)))))
(if (eq end (point-max))
(signal 'end-of-buffer nil)
(select-window (car windows))
;; `window-end' might return nil.
(if end
(goto-char end))
(vertical-motion (- next-screen-context-lines))
(set-window-start (car windows) (point)))))))
(let ((opoint (point)) (owin (selected-window)))
(while
;; If we are too near EOB, try scrolling the previous window.
(condition-case nil (progn (scroll-up arg) nil)
(end-of-buffer
(condition-case nil (progn (follow-previous-window) t)
(error
(select-window owin)
(goto-char opoint)
(signal 'end-of-buffer nil))))))
(unless (and scroll-preserve-screen-position
(get this-command 'scroll-command))
(goto-char opoint))
(setq follow-fixed-window t)))))
(put 'follow-scroll-up 'scroll-command t)
;;;###autoload
(defun follow-scroll-down (&optional arg)
"Scroll text in a Follow mode window chain down.
......@@ -492,27 +548,20 @@ the top window in the chain will be visible in the bottom window.
If called with an argument, scroll ARG lines down.
Negative ARG means scroll upward.
Works like `scroll-up' when not in Follow mode."
Works like `scroll-down' when not in Follow mode."
(interactive "P")
(cond ((not follow-mode)
(scroll-up arg))
(arg
(save-excursion (scroll-down arg)))
(scroll-down arg))
((eq arg '-)
(follow-scroll-up))
(t
(let* ((windows (follow-all-followers))
(win (car (reverse windows)))
(start (window-start (car windows))))
(if (eq start (point-min))
(signal 'beginning-of-buffer nil)
(select-window win)
(goto-char start)
(vertical-motion (- (- (window-height win)
(if header-line-format 2 1)
next-screen-context-lines)))
(set-window-start win (point))
(goto-char start)
(vertical-motion (- next-screen-context-lines 1))
(setq follow-internal-force-redisplay t))))))
(let ((opoint (point)))
(scroll-down arg)
(unless (and scroll-preserve-screen-position
(get this-command 'scroll-command))
(goto-char opoint))
(setq follow-fixed-window t)))))
(put 'follow-scroll-down 'scroll-command t)
(declare-function comint-adjust-point "comint" (window))
(defvar comint-scroll-show-maximum-output)
......@@ -766,15 +815,16 @@ from the selected window."
Return (END-POS END-OF-BUFFER).
Actually, the position returned is the start of the line after
the last fully-visible line in WIN. If WIN is nil, the selected
window is used."
the last fully-visible line in WIN. END-OF-BUFFER is t when EOB
is fully-visible in WIN. If WIN is nil, the selected window is
used."
(let* ((win (or win (selected-window)))
(edges (window-inside-pixel-edges win))
(ht (- (nth 3 edges) (nth 1 edges)))
(last-line-pos (posn-point (posn-at-x-y 0 (1- ht) win))))
(if (pos-visible-in-window-p last-line-pos win)
(let ((end (window-end win t)))
(list end (= end (point-max))))
(list end (pos-visible-in-window-p (point-max) win)))
(list last-line-pos nil))))
(defun follow-calc-win-start (windows pos win)
......@@ -1008,7 +1058,7 @@ should be a member of WINDOWS, starts at position START."
(goto-char start)
(vertical-motion 0 win)
(dolist (w windows-before)
(vertical-motion (- 1 (window-text-height w)) w))
(vertical-motion (- (window-text-height w)) w))
(point))))
......@@ -1130,138 +1180,144 @@ non-first windows in Follow mode."
(cl-assert (eq (window-buffer win) (current-buffer)))
(when (and follow-mode
(not (window-minibuffer-p win)))
(let* ((dest (point))
(windows (follow-all-followers win))
(win-start-end (progn
(follow-update-window-start (car windows))
(follow-windows-start-end windows)))
(aligned (follow-windows-aligned-p win-start-end))
(visible (follow-pos-visible dest win win-start-end))
selected-window-up-to-date)
(unless (and aligned visible)
(setq follow-windows-start-end-cache nil))
;; Select a window to display point.
(unless follow-internal-force-redisplay
(if (eq dest (point-max))
;; Be careful at point-max: the display can be aligned
;; while DEST can be visible in several windows.
(cond
;; Select the current window, but only when the display
;; is correct. (When inserting characters in a tail
;; window, the display is not correct, as they are
;; shown twice.)
;;
;; Never stick to the current window after a deletion.
;; Otherwise, when typing `DEL' in a window showing
;; only the end of the file, a character would be
;; removed from the window above, which is very
;; unintuitive.
((and visible
aligned
(not (memq this-command
'(backward-delete-char
delete-backward-char
backward-delete-char-untabify
kill-region))))
(follow-debug-message "Max: same"))
;; If the end is visible, and the window doesn't
;; seems like it just has been moved, select it.
((follow-select-if-end-visible win-start-end)
(follow-debug-message "Max: end visible")
(setq visible t aligned nil)
(goto-char dest))
;; Just show the end...
(t
(follow-debug-message "Max: default")
(select-window (car (last windows)))
(goto-char dest)
(setq visible nil aligned nil)))
;; We're not at the end, here life is much simpler.
(cond
;; This is the normal case!
;; It should be optimized for speed.
((and visible aligned)
(follow-debug-message "same"))
;; Pick a position in any window. If the display is ok,
;; this picks the `correct' window.
((follow-select-if-visible dest win-start-end)
(follow-debug-message "visible")
(goto-char dest)
;; Perform redisplay, in case line is partially visible.
(setq visible nil))
;; Not visible anywhere else, lets pick this one.
(visible
(follow-debug-message "visible in selected."))
;; If DEST is before the first window start, select the
;; first window.
((< dest (nth 1 (car win-start-end)))
(follow-debug-message "before first")
(select-window (car windows))
(goto-char dest)
(setq visible nil aligned nil))
;; If we can position the cursor without moving the first
;; window, do it. This is the case that catches `RET' at
;; the bottom of a window.
((follow-select-if-visible-from-first dest windows)
(follow-debug-message "Below first")
(setq visible t aligned t))
;; None of the above. Stick to the selected window.
(t
(follow-debug-message "None")
(setq visible nil aligned nil))))
;; If a new window was selected, make sure that the old is
;; not scrolled when point is outside the window.
(unless (eq win (selected-window))
(let ((p (window-point win)))
(set-window-start win (window-start win) nil)
(set-window-point win p))))
(unless visible
;; If point may not be visible in the selected window,
;; perform a redisplay; this ensures scrolling.
(let ((opoint (point)))
(redisplay)
;; If this `redisplay' moved point, we got clobbered by a
;; previous call to `set-window-start'. Try again.
(when (/= (point) opoint)
(goto-char opoint)
(redisplay)))
(setq selected-window-up-to-date t)
(follow-avoid-tail-recenter)
(setq win-start-end (follow-windows-start-end windows)
follow-windows-start-end-cache nil
aligned nil))
;; Now redraw the windows around the selected window.
(unless (and (not follow-internal-force-redisplay)
(or aligned
(follow-windows-aligned-p win-start-end))
(follow-point-visible-all-windows-p win-start-end))
(setq follow-internal-force-redisplay nil)
(follow-redisplay windows (selected-window)
selected-window-up-to-date)
(setq win-start-end (follow-windows-start-end windows)
follow-windows-start-end-cache nil)
;; Point can end up in another window when DEST is at
;; the beginning of the buffer and the selected window is
;; not the first. It can also happen when long lines are
;; used and there is a big difference between the width of
;; the windows. (When scrolling one line in a wide window
;; which will cause a move larger that an entire small
;; window.)
(unless (follow-pos-visible dest win win-start-end)
(follow-select-if-visible dest win-start-end)
(goto-char dest)))
;; If the region is visible, make it look good when spanning
;; multiple windows.
(when (region-active-p)
(follow-maximize-region
(selected-window) windows win-start-end)))
(let ((windows (follow-all-followers win)))
;; If we've explicitly scrolled, align the windows first.
(when follow-fixed-window
(follow-debug-message "fixed")
(follow-redisplay windows win)
(goto-char (follow-get-scrolled-point (point) windows))
(setq follow-fixed-window nil))
(let* ((dest (point))
(win-start-end (progn
(follow-update-window-start (car windows))
(follow-windows-start-end windows)))
(aligned (follow-windows-aligned-p win-start-end))
(visible (follow-pos-visible dest win win-start-end))
selected-window-up-to-date)
(unless (and aligned visible)
(setq follow-windows-start-end-cache nil))
;; Select a window to display point.
(unless follow-internal-force-redisplay
(if (eq dest (point-max))
;; Be careful at point-max: the display can be aligned
;; while DEST can be visible in several windows.
(cond
;; Select the current window, but only when the display
;; is correct. (When inserting characters in a tail
;; window, the display is not correct, as they are
;; shown twice.)
;;
;; Never stick to the current window after a deletion.
;; Otherwise, when typing `DEL' in a window showing
;; only the end of the file, a character would be
;; removed from the window above, which is very
;; unintuitive.
((and visible
aligned
(not (memq this-command
'(backward-delete-char
delete-backward-char
backward-delete-char-untabify
kill-region))))
(follow-debug-message "Max: same"))
;; If the end is visible, and the window doesn't
;; seems like it just has been moved, select it.
((follow-select-if-end-visible win-start-end)
(follow-debug-message "Max: end visible")
(setq visible t aligned nil)
(goto-char dest))
;; Just show the end...
(t
(follow-debug-message "Max: default")
(select-window (car (last windows)))
(goto-char dest)
(setq visible nil aligned nil)))
;; We're not at the end, here life is much simpler.
(cond
;; This is the normal case!
;; It should be optimized for speed.
((and visible aligned)
(follow-debug-message "same"))
;; Pick a position in any window. If the display is ok,
;; this picks the `correct' window.
((follow-select-if-visible dest win-start-end)
(follow-debug-message "visible")
(goto-char dest)
;; Perform redisplay, in case line is partially visible.
(setq visible nil))
;; Not visible anywhere else, lets pick this one.
(visible
(follow-debug-message "visible in selected."))
;; If DEST is before the first window start, select the
;; first window.
((< dest (nth 1 (car win-start-end)))
(follow-debug-message "before first")
(select-window (car windows))
(goto-char dest)
(setq visible nil aligned nil))
;; If we can position the cursor without moving the first
;; window, do it. This is the case that catches `RET' at
;; the bottom of a window.
((follow-select-if-visible-from-first dest windows)
(follow-debug-message "Below first")
(setq visible t aligned t))
;; None of the above. Stick to the selected window.
(t
(follow-debug-message "None")
(setq visible nil aligned nil))))
;; If a new window was selected, make sure that the old is
;; not scrolled when point is outside the window.
(unless (eq win (selected-window))
(let ((p (window-point win)))
(set-window-start win (window-start win) nil)
(set-window-point win p))))
(unless visible
;; If point may not be visible in the selected window,
;; perform a redisplay; this ensures scrolling.
(let ((opoint (point)))
(redisplay)
;; If this `redisplay' moved point, we got clobbered by a
;; previous call to `set-window-start'. Try again.
(when (/= (point) opoint)
(goto-char opoint)
(redisplay)))
(setq selected-window-up-to-date t)
(follow-avoid-tail-recenter)
(setq win-start-end (follow-windows-start-end windows)
follow-windows-start-end-cache nil
aligned nil))
;; Now redraw the windows around the selected window.
(unless (and (not follow-internal-force-redisplay)
(or aligned
(follow-windows-aligned-p win-start-end))
(follow-point-visible-all-windows-p win-start-end))
(setq follow-internal-force-redisplay nil)
(follow-redisplay windows (selected-window)
selected-window-up-to-date)
(setq win-start-end (follow-windows-start-end windows)
follow-windows-start-end-cache nil)
;; Point can end up in another window when DEST is at
;; the beginning of the buffer and the selected window is
;; not the first. It can also happen when long lines are
;; used and there is a big difference between the width of
;; the windows. (When scrolling one line in a wide window
;; which will cause a move larger that an entire small
;; window.)
(unless (follow-pos-visible dest win win-start-end)
(follow-select-if-visible dest win-start-end)
(goto-char dest)))
;; If the region is visible, make it look good when spanning
;; multiple windows.
(when (region-active-p)
(follow-maximize-region
(selected-window) windows win-start-end))))
;; Whether or not the buffer was in follow mode, update windows
;; displaying the tail so that Emacs won't recenter them.
......
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