This is mostly factored out from tabulated-list.el (with bugs fixed).
* doc/lispref/modes.texi (Header Lines): Document it.
* lisp/display-line-numbers.el (header-line-indent): New variable.
(header-line-indent--line-number-width)
(header-line-indent--watch-line-number-width)
(header-line-indent--window-scroll-function): New helper functions.
(header-line-indent-mode): New minor mode.
* lisp/display-line-numbers.el (header-line-indent-width): New
variable.
* lisp/emacs-lisp/tabulated-list.el (tabulated-list-line-number-width)
(tabulated-list-watch-line-number-width)
(tabulated-list-window-scroll-function): Make into obsolete aliases.
(tabulated-list-mode): Use 'header-line-indent-mode'.
* lisp/emacs-lisp/tabulated-list.el (tabulated-list-init-header):
Adjust the header line format and computation.
* src/buffer.c (syms_of_buffer): Mention header-line-indent-mode.
This variable, local in every buffer, specifies how to display the
header line, for windows displaying the buffer. The format of the value
is the same as for @code{mode-line-format} (@pxref{Mode Line Data}).
-It is normally @code{nil}, so that ordinary buffers have no header line.
+It is normally @code{nil}, so that ordinary buffers have no header
+line.
+
+@findex header-line-indent-mode
+If @code{display-line-numbers-mode} is used, and you want the header
+line to be indented by the same amount as the buffer contents, you can
+use the @code{header-line-indent-mode} minor mode. This minor mode
+keeps the @code{header-line-indent} variable updated, so that you can
+say something like:
+
+@lisp
+(setq header-line-format
+ `("" header-line-format ,my-header-line))
+@end lisp
+
+This can be useful if you're displaying columnar data, and the header
+line should align with that data in the buffer.
@end defvar
@defun window-header-line-height &optional window
\f
* Lisp Changes in Emacs 29.1
++++
+** New minor mode 'header-line-indent-mode'.
+This is meant to be used in modes that have a header line that should
+be kept aligned with the buffer contents when the user switches
+'display-line-numbers-mode' on or off.
+
+++
** New predicate 'char-uppercase-p'.
This returns non-nil if its argument its an uppercase character.
(define-globalized-minor-mode global-display-line-numbers-mode
display-line-numbers-mode display-line-numbers--turn-on)
+\f
+
+;;;###autoload
+(defvar header-line-indent ""
+ "String to indent at the start if the header line.
+This is used in `header-line-indent-mode', and buffers that have
+this switched on should have a `header-line-format' that look like:
+
+ (\"\" header-line-indent THE-REST...)
+
+Also see `header-line-indent-width'.")
+
+;;;###autoload
+(defvar header-line-indent-width 0
+ "The width of the current line numbers displayed.
+This is updated when `header-line-indent-mode' is switched on.
+
+Also see `header-line-indent'.")
+
+(defun header-line-indent--line-number-width ()
+ "Return the width taken by `display-line-numbers' in the current buffer."
+ ;; line-number-display-width returns the value for the selected
+ ;; window, which might not be the window in which the current buffer
+ ;; is displayed.
+ (if (not display-line-numbers)
+ 0
+ (let ((cbuf-window (get-buffer-window (current-buffer) t)))
+ (if (window-live-p cbuf-window)
+ (with-selected-window cbuf-window
+ (truncate (line-number-display-width 'columns)))
+ 4))))
+
+(defun header-line-indent--watch-line-number-width (_window)
+ (let ((width (header-line-indent--line-number-width)))
+ (setq header-line-indent-width width)
+ (unless (= (length header-line-indent) width)
+ (setq header-line-indent (make-string width ?\s)))))
+
+(defun header-line-indent--window-scroll-function (window _start)
+ (let ((width (with-selected-window window
+ (truncate (line-number-display-width 'columns)))))
+ (setq header-line-indent-width width)
+ (unless (= (length header-line-indent) width)
+ (setq header-line-indent (make-string width ?\s)))))
+
+;;;###autoload
+(define-minor-mode header-line-indent-mode
+ "Mode to indent the header line in `display-line-numbers-mode' buffers.
+This means that the header line will be kept indented so that it
+has blank space that's as wide as the displayed line numbers in
+the buffer.
+
+Buffers that have this switched on should have a
+`header-line-format' that look like:
+
+ (\"\" header-line-indent THE-REST...)
+
+The `header-line-indent-width' variable is also kept updated, and
+has the width of `header-line-format'. This can be used, for
+instance, in `:align-to' specs, like:
+
+ (space :align-to (+ header-line-indent-width 10))"
+ :lighter nil
+ (if header-line-indent-mode
+ (progn
+ (setq-local header-line-indent ""
+ header-line-indent-width 0)
+ (add-hook 'pre-redisplay-functions
+ #'header-line-indent--watch-line-number-width nil t)
+ (add-hook 'window-scroll-functions
+ #'header-line-indent--window-scroll-function nil t))
+ (setq-local header-line-indent ""
+ header-line-indent-width 0)
+ (remove-hook 'pre-redisplay-functions
+ #'header-line-indent--watch-line-number-width t)
+ (remove-hook 'window-scroll-functions
+ #'header-line-indent--window-scroll-function t)))
+
(provide 'display-line-numbers)
;;; display-line-numbers.el ends here
Populated by `tabulated-list-init-header'.")
(defvar tabulated-list--header-overlay nil)
-(defun tabulated-list-line-number-width ()
- "Return the width taken by `display-line-numbers' in the current buffer."
- ;; line-number-display-width returns the value for the selected
- ;; window, which might not be the window in which the current buffer
- ;; is displayed.
- (if (not display-line-numbers)
- 0
- (let ((cbuf-window (get-buffer-window (current-buffer) t)))
- (if (window-live-p cbuf-window)
- (with-selected-window cbuf-window
- (line-number-display-width 'columns))
- 4))))
+(define-obsolete-function-alias 'tabulated-list-line-number-width
+ 'header-line-indent--line-number-width "29.1")
+(define-obsolete-function-alias 'tabulated-list-watch-line-number-width
+ 'header-line-indent--watch-line-number-width "29.1")
+(define-obsolete-function-alias 'tabulated-list-watch-line-number-width
+ 'header-line-indent--watch-line-number-width "29.1")
+(define-obsolete-function-alias 'tabulated-list-window-scroll-function
+ 'header-line-indent--window-scroll-function "29.1")
(defun tabulated-list-init-header ()
"Set up header line for the Tabulated List buffer."
(hcols (mapcar #'car tabulated-list-format))
(tabulated-list--near-rows (list hcols hcols))
(cols nil))
- (if display-line-numbers
- (setq x (+ x (tabulated-list-line-number-width))))
- (push (propertize " " 'display `(space :align-to ,x)) cols)
+ (push (propertize " " 'display
+ `(space :align-to (+ header-line-indent-width ,x)))
+ cols)
(dotimes (n len)
(let* ((col (aref tabulated-list-format n))
(not-last-col (< n (1- len)))
(when (> shift 0)
(setq cols
(cons (car cols)
- (cons (propertize (make-string shift ?\s)
- 'display
- `(space :align-to ,(+ x shift)))
- (cdr cols))))
+ (cons
+ (propertize
+ (make-string shift ?\s)
+ 'display
+ `(space :align-to
+ (+ header-line-indent-width ,(+ x shift))))
+ (cdr cols))))
(setq x (+ x shift)))))
(if (>= pad-right 0)
- (push (propertize " "
- 'display `(space :align-to ,next-x)
- 'face 'fixed-pitch)
+ (push (propertize
+ " "
+ 'display `(space :align-to
+ (+ header-line-indent-width ,next-x))
+ 'face 'fixed-pitch)
cols))
(setq x next-x)))
(setq cols (apply 'concat (nreverse cols)))
(if tabulated-list-use-header-line
- (setq header-line-format cols)
+ (setq header-line-format (list "" 'header-line-indent cols))
(setq-local tabulated-list--header-string cols))))
(defun tabulated-list-print-fake-header ()
(interactive "p")
(tabulated-list-widen-current-column (- n)))
-(defvar tabulated-list--current-lnum-width nil)
-(defun tabulated-list-watch-line-number-width (_window)
- (if display-line-numbers
- (let ((lnum-width (tabulated-list-line-number-width)))
- (when (not (= tabulated-list--current-lnum-width lnum-width))
- (setq-local tabulated-list--current-lnum-width lnum-width)
- (tabulated-list-init-header)))))
-
-(defun tabulated-list-window-scroll-function (window _start)
- (if display-line-numbers
- (let ((lnum-width
- (with-selected-window window
- (line-number-display-width 'columns))))
- (when (not (= tabulated-list--current-lnum-width lnum-width))
- (setq-local tabulated-list--current-lnum-width lnum-width)
- (tabulated-list-init-header)))))
-
(defun tabulated-list-next-column (&optional arg)
"Go to the start of the next column after point on the current line.
If ARG is provided, move that many columns."
;; Avoid messing up the entries' display just because the first
;; column of the first entry happens to begin with a R2L letter.
(setq bidi-paragraph-direction 'left-to-right)
- ;; This is for if/when they turn on display-line-numbers
- (add-hook 'display-line-numbers-mode-hook #'tabulated-list-revert nil t)
- ;; This is for if/when they customize the line-number face or when
- ;; the line-number width needs to change due to scrolling.
- (setq-local tabulated-list--current-lnum-width 0)
- (add-hook 'pre-redisplay-functions
- #'tabulated-list-watch-line-number-width nil t)
- (add-hook 'window-scroll-functions
- #'tabulated-list-window-scroll-function nil t))
+ (header-line-indent-mode))
(put 'tabulated-list-mode 'mode-class 'special)
&BVAR (current_buffer, header_line_format),
Qnil,
doc: /* Analogous to `mode-line-format', but controls the header line.
-The header line appears, optionally, at the top of a window;
-the mode line appears at the bottom. */);
+The header line appears, optionally, at the top of a window; the mode
+line appears at the bottom.
+
+Also see `header-line-indent-mode' if `display-line-number-mode' is
+used. */);
DEFVAR_PER_BUFFER ("mode-line-format", &BVAR (current_buffer, mode_line_format),
Qnil,
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