Function: ruler-mode-mouse-grab-any-column

ruler-mode-mouse-grab-any-column is an interactive and byte-compiled function defined in ruler-mode.el.gz.

Signature

(ruler-mode-mouse-grab-any-column START-EVENT)

Documentation

Drag a column symbol on the ruler.

Start dragging on mouse down event START-EVENT, and update the column symbol value with the current value of the ruler graduation while dragging. See also the variable ruler-mode-dragged-symbol.

Key Bindings

Source Code

;; Defined in /usr/src/emacs/lisp/ruler-mode.el.gz
(defun ruler-mode-mouse-grab-any-column (start-event)
  "Drag a column symbol on the ruler.
Start dragging on mouse down event START-EVENT, and update the column
symbol value with the current value of the ruler graduation while
dragging.  See also the variable `ruler-mode-dragged-symbol'."
  (interactive "e")
  (setq ruler-mode-dragged-symbol nil)
  (let* ((start (event-start start-event))
         col newc oldc)
    (save-selected-window
      (select-window (posn-window start))
      (setq col  (ruler-mode-window-col (car (posn-col-row start)))
            newc (+ col (ruler-mode-text-scaled-window-hscroll)))
      (and
       (>= col 0) (< col (ruler-mode-text-scaled-window-width))
       (cond

        ;; Handle the fill column.
        ((eq newc fill-column)
         (setq oldc fill-column
               ruler-mode-dragged-symbol 'fill-column)
         t) ;; Start dragging

        ;; Handle the comment column.
        ((eq newc comment-column)
         (setq oldc comment-column
               ruler-mode-dragged-symbol 'comment-column)
         t) ;; Start dragging

        ;; Handle the goal column.
        ;; A. On mouse down on the goal column character on the ruler,
        ;;    update the `goal-column' value while dragging.
        ;; B. If `goal-column' is nil, set the goal column where the
        ;;    mouse is clicked.
        ;; C. On mouse click on the goal column character on the
        ;;    ruler, unset the goal column.
        ((eq newc goal-column)          ; A. Drag the goal column.
         (setq oldc goal-column
               ruler-mode-dragged-symbol 'goal-column)
         t) ;; Start dragging

        ((null goal-column)             ; B. Set the goal column.
         (setq oldc goal-column
               goal-column newc)
         ;; mouse-2 coming AFTER drag-mouse-2 invokes `ding'.  This
         ;; `ding' flushes the next messages about setting goal
         ;; column.  So here I force fetch the event(mouse-2) and
         ;; throw away.
         (read--potential-mouse-event)
         ;; Ding BEFORE `message' is OK.
         (when ruler-mode-set-goal-column-ding-flag
           (ding))
         (message "Goal column set to %d (click on %s again to unset it)"
                  newc
                  (propertize (char-to-string ruler-mode-goal-column-char)
                              'face 'ruler-mode-goal-column))
         nil) ;; Don't start dragging.
        )
       (if (eq 'click (ruler-mode-mouse-drag-any-column-iteration
                       (posn-window start)))
           (when (eq 'goal-column ruler-mode-dragged-symbol)
             ;; C. Unset the goal column.
             (set-goal-column t))
         ;; At end of dragging, report the updated column symbol.
         (message "%s is set to %d (was %d)"
                  ruler-mode-dragged-symbol
                  (symbol-value ruler-mode-dragged-symbol)
                  oldc))))))