GNU bug report logs - #3602
23.0.94; window-line-height problems

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Message #5 received at submit <at> emacsbugs.donarmstrong.com (full text, mbox):

From: "Drew Adams" <drew.adams <at> oracle.com>
To: <emacs-pretest-bug <at> gnu.org>
Subject: 23.0.94; window-line-height problems
Date: Wed, 17 Jun 2009 22:39:55 -0700

The behavior of this function seems broken, at least for LINE =
mode-line or header-line. And the doc is not good.
 
Doc string of `window-line-height' says this:
 
"Return height of current line if LINE is omitted or nil.  Return
height of header or mode line if LINE is `header-line' and
`mode-line'."
 
That seems to say that if you have a header line, then you can get its
height in pixels this way (window-line-height 'header-line), and
similarly for mode-line. But that doesn't seem to work.
 
emacs -Q
(setq Info-use-header-line t)
C-h i
M-: (window-line-height 'header-line) returns nil
M-: (window-line-height 'mode-line) returns nil
 
This part of the doc string is incomprehensible to me:
 
"Return nil if window display is not up-to-date." What does that mean?
And then it says "In that case, use `pos-visible-in-window-p' to
obtain the information." How to do that? What args to use with
`pos-visible-in-window-p', to find out the `window-line-height' for
the header-line, for instance? This paragraph is quite unclear to me.
 
Also, the function is called *-height, and the first part of the doc
string says that it returns the "height in pixels". But later in the
doc string we learn that the value (returned, presumably) is a list
(HEIGHT VPOS YPOS OFFBOT). That's contradictory. If the height in
pixels is returned, that is presumably an integer, not a list.
 
The Elisp manual repeats all of the confusion and other defects of the
doc string. In fact, it is almost verbatim the same text.
 

In GNU Emacs 23.0.94.1 (i386-mingw-nt5.1.2600)
 of 2009-05-24 on SOFT-MJASON
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (3.4)'
 

Message #8 received at 3602 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: "Drew Adams" <drew.adams <at> oracle.com>
Cc: 3602 <at> debbugs.gnu.org
Subject: Re: bug#3602: 23.0.94; window-line-height problems
Date: Sun, 09 Feb 2014 19:33:37 -0800

"Drew Adams" <drew.adams <at> oracle.com> writes:

> The behavior of this function seems broken, at least for LINE =
> mode-line or header-line. And the doc is not good.
>
> Doc string of `window-line-height' says this:
>
> "Return height of current line if LINE is omitted or nil.  Return
> height of header or mode line if LINE is `header-line' and
> `mode-line'."
>
> That seems to say that if you have a header line, then you can get its
> height in pixels this way (window-line-height 'header-line), and
> similarly for mode-line. But that doesn't seem to work.

(window-line-height 'mode-line)
=> nil

So I can confirm this bug.

-- 
(domestic pets only, the antidote for overdose, milk.)
  bloggy blog http://lars.ingebrigtsen.no/

Message #13 received at 3602 <at> debbugs.gnu.org (full text, mbox):

From: martin rudalics <rudalics <at> gmx.at>
To: Lars Ingebrigtsen <larsi <at> gnus.org>
Cc: 3602 <at> debbugs.gnu.org, Drew Adams <drew.adams <at> oracle.com>
Subject: Re: bug#3602: 23.0.94; window-line-height problems
Date: Mon, 10 Feb 2014 09:14:43 +0100

>> That seems to say that if you have a header line, then you can get its
>> height in pixels this way (window-line-height 'header-line), and
>> similarly for mode-line. But that doesn't seem to work.
>
> (window-line-height 'mode-line)
> => nil
>
> So I can confirm this bug.

The doc-string of `window-line-height' says ...

     Return nil if window display is not up-to-date.  In that case, use
    `pos-visible-in-window-p' to obtain the information.

... and the Elisp manual says ...

     If the display is not up to date, `window-line-height' returns
     `nil'.  In that case, `pos-visible-in-window-p' may be used to
     obtain related information.

... so I wonder how you can "confirm this bug" ;-)

martin

Message #16 received at 3602 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: martin rudalics <rudalics <at> gmx.at>
Cc: 3602 <at> debbugs.gnu.org, Drew Adams <drew.adams <at> oracle.com>
Subject: Re: bug#3602: 23.0.94; window-line-height problems
Date: Mon, 10 Feb 2014 00:18:47 -0800

martin rudalics <rudalics <at> gmx.at> writes:

>> (window-line-height 'mode-line)
>> => nil
>>
>> So I can confirm this bug.
>
> The doc-string of `window-line-height' says ...
>
>      Return nil if window display is not up-to-date.  In that case, use
>     `pos-visible-in-window-p' to obtain the information.
>
> ... and the Elisp manual says ...
>
>      If the display is not up to date, `window-line-height' returns
>      `nil'.  In that case, `pos-visible-in-window-p' may be used to
>      obtain related information.
>
> ... so I wonder how you can "confirm this bug" ;-)

Is the window display not up to date when I hit `C-x C-e' after the form
up there?

Apparently not:

(progn (sit-for 1) (window-line-height 'mode-line))
=> (22 0 748 0)

So this doesn't seem to be a bug.  Closing.

-- 
(domestic pets only, the antidote for overdose, milk.)
  bloggy blog http://lars.ingebrigtsen.no/

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