Re: line-pixel-height beyond eol

[Tak Kunihiro <tkk@misasa.okayama-u.ac.jp>]

Thank you for the response.

>> Thus I have to know height of pixel on the top window line.
> 
> Can you use vertical-motion for that?

After try and error, I learned how to get height of pixel on
visual-line using `vertical-motion' and `posn-x-y' as shown below.

However, when (window-hscroll) is large, I cannot get y location of
cursor using `posn-x-y'.  Can you give me suggestion how to get y
location of cursor even when when (window-hscroll) is large?


(defun pixel-visual-line-height ()
  "Return height in pixels of text line in the selected window.

Value is the height of pixels in the line visually shown by
current screen.  Note that `line-pixel-height' returns the
maximum height of a line."
  (let ((pos-save (window-start)) ; save window configuration
        (vs-save (window-vscroll nil t))
        (height (frame-char-height)) ; (line-pixel-height)
        pos-a pos-b y-a y-b
        height-meas)
    (save-excursion ; measure actual height
      (beginning-of-visual-line)
      (set-window-vscroll nil 0 t)
      (set-window-start nil (point) t)
      (and (setq pos-a (posn-at-point))
           (vertical-motion 1)
           (setq pos-b (posn-at-point))
           (integerp (setq y-a (cdr (posn-x-y pos-a))))
           (integerp (setq y-b (cdr (posn-x-y pos-b))))
           (integerp (setq height-meas (- y-b y-a)))
           (setq height height-meas))
      (set-window-start nil pos-save t) ; restore window configuration
      (set-window-vscroll nil vs-save t))
    height))