Re: Add a function that returns pixel distance between points?

[Ihor Radchenko <yantar92@gmail.com>]

Yuan Fu <casouri@gmail.com> writes:

> When the text is displayed in variable-pitch font, the bars aren’t aligned. I’m using display property (space :align-to) to align those bars. To know with pixel position to align to, I need to calculate each column’s pixel width, and met the difficulties mentioned earlier.

You can do it in temp buffer with line numbers and wrap prefix disabled.
Something like

(defun string-display-pixel-width (string &optional mode)
  "Calculate pixel width of STRING.
Optional MODE specifies major mode used for display."
  (with-temp-buffer
    (with-silent-modifications
      (setf (buffer-string) string))
    (when (fboundp mode)
      (funcall mode)
      (font-lock-fontify-buffer))
    (let (wrap-prefix display-line-numbers)
      (if (get-buffer-window (current-buffer))
	  (car (window-text-pixel-size nil (line-beginning-position) (point)))
        (set-window-buffer nil (current-buffer))
        (car (window-text-pixel-size nil (line-beginning-position) (point)))))))

Best,
Ihor