Re: Patch to vertically center line content when using line-spacing variable

[john muhl <email@johnmuhl.me>]

On Sun, 2021-04-25 at 21:41 +0200, Lars Ingebrigtsen wrote:
> email@johnmuhl.me writes:
> 
> > I am interested in this landing and contacted (and cc'd) Jesse and
> > the
> > FSF paperwork was completed around June 2020. Is there anything else
> > holding this back now?
> > 
> > https://lists.gnu.org/archive/html/emacs-devel/2020-01/msg00721.html
> > has links to the previous discussion.
> 
> I've included the patch below.
> 
> I've never used the `line-spacing' variable myself (and my guess is
> that
> few do, which is probably why your message didn't get any responses),
> but I did a
> 
>   (setq line-spacing 20)
> 
> now, and I see that this puts more space at the bottom of the line. 
> The
> proposed patch allows centring instead, which seems eminently
> reasonable
> to me.  (Perhaps this should even be the default?)
> 
> Does anybody have any comments here before I apply the patch?
> 

Thanks for taking look. I've been using the proposed patch the last
couple of weeks and it works for me. The echo area does not handle
it perfectly but it also doesn't perfectly handle the current behavior
of non-nil line-spacing so hopefully not a blocker for landing.

I added the following line to make it settable from customize.

---
 lisp/cus-start.el | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lisp/cus-start.el b/lisp/cus-start.el
index b7afef6516..21ad616cc9 100644
--- a/lisp/cus-start.el
+++ b/lisp/cus-start.el
@@ -154,6 +154,7 @@ minibuffer-prompt-properties--setter
                                       "21.1")
             (line-spacing display (choice (const :tag "none" nil)
number)
                           "22.1")
+             (line-spacing-vertical-center display boolean "28.1")
             (cursor-in-non-selected-windows
              cursor ,cursor-type-types nil
              :tag "Cursor In Non-selected Windows"
--