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

[Yuan Fu]

> On Jan 31, 2021, at 12:52 AM, Ihor Radchenko <yantar92@gmail.com> wrote:
> 
> 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

Thanks, I’ll try that and see if it is fast enough for my use :-)

Yuan