> Begin forwarded message:
> 
> From: Yuan Fu <casouri@gmail.com>
> Subject: Re: bug#43469: 28.0.50; window-text-pixel-size returns incorrect value when line-prefix is set
> Date: September 19, 2020 at 2:33:03 PM GMT-4
> To: Eli Zaretskii <eliz@gnu.org>
> Cc: 43469@debbugs.gnu.org
> 
> 
> 
>> On Sep 18, 2020, at 3:22 PM, Eli Zaretskii <eliz@gnu.org> wrote:
>> 
>>> From: Yuan Fu <casouri@gmail.com>
>>> Date: Fri, 18 Sep 2020 13:05:15 -0400
>>> Cc: 43469@debbugs.gnu.org
>>> 
>>>>> (progn (insert "xxxxxxxxxxxxxx")
>>>>>     (print (car (window-text-pixel-size
>>>>>                  nil (line-beginning-position) (line-end-position))))
>>>>>     (put-text-property (line-beginning-position) (line-end-position)
>>>>>                        'line-prefix "   ")
>>>>>     (print (car (window-text-pixel-size
>>>>>                  nil (line-beginning-position) (line-end-position)))))
>>>>> 
>>>>> Prints first 98, then 119
>>>> 
>>>> Why do you think this is a bug?
>>> 
>>> I thought the pixel width shouldn’t include the line-prefix?
>> 
>> It should.  From the function's doc string:
>> 
>> This function exists to allow Lisp programs to adjust the dimensions
>> of WINDOW to the buffer text it needs to display.
>> 
>> When you want to know how wide a window you need for displaying some
>> text, you do want the line-prefix part accounted for.
> 
> I see. I managed to use (window-text-pixel-size nil (point) (point)) to calculate the prefix width and subtract it out. Thanks.
> 
> Yuan
>