bug#59122: 29.0.50; global-text-scale-adjust not working

[Gregory Heytings <gregory@heytings.org>]

[-- Attachment #1: Type: text/plain, Size: 88 bytes --]


Stefan, Rudolf, can you try the attached patch and see if it fixes the 
issue?

Thanks.

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: Fix-global-face-scaling-bug-due-to-rounding.patch --]
[-- Type: text/x-diff; name=Fix-global-face-scaling-bug-due-to-rounding.patch, Size: 2347 bytes --]

From 288401146162e67efa8f4a23c790fadeb1b92d6a Mon Sep 17 00:00:00 2001
From: Gregory Heytings <gregory@heytings.org>
Date: Wed, 9 Nov 2022 16:16:22 +0000
Subject: [PATCH] Fix global face scaling bug due to rounding.

* lisp/face-remap.el (global-text-scale-adjust): Try again if the face
height did not actually change.
(global-text-scale-adjust--increment-factor): New internal variable.
Fixes bug#59122.
---
 lisp/face-remap.el | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/lisp/face-remap.el b/lisp/face-remap.el
index 432385587b..2d83d804c6 100644
--- a/lisp/face-remap.el
+++ b/lisp/face-remap.el
@@ -461,6 +461,8 @@ global-text-scale-adjust-limits
 
 (defvar global-text-scale-adjust--default-height nil)
 
+(defvar global-text-scale-adjust--increment-factor 5)
+
 ;;;###autoload (define-key ctl-x-map [(control meta ?+)] 'global-text-scale-adjust)
 ;;;###autoload (define-key ctl-x-map [(control meta ?=)] 'global-text-scale-adjust)
 ;;;###autoload (define-key ctl-x-map [(control meta ?-)] 'global-text-scale-adjust)
@@ -499,16 +501,22 @@ global-text-scale-adjust
            (cur (face-attribute 'default :height))
            (inc
             (pcase key
-              (?- (* (- increment) 5))
+              (?- (* (- increment)
+                     global-text-scale-adjust--increment-factor))
               (?0 (- global-text-scale-adjust--default-height cur))
-              (_ (* increment 5))))
+              (_ (* increment
+                    global-text-scale-adjust--increment-factor))))
            (new (+ cur inc)))
       (when (< (car global-text-scale-adjust-limits)
                new
                (cdr global-text-scale-adjust-limits))
         (let ((frame-inhibit-implied-resize
                (not global-text-scale-adjust-resizes-frames)))
-          (set-face-attribute 'default nil :height new)))
+          (set-face-attribute 'default nil :height new)
+          (when (= cur (face-attribute 'default :height))
+            (setq global-text-scale-adjust--increment-factor
+                  (1+ global-text-scale-adjust--increment-factor))
+            (global-text-scale-adjust increment))))
       (when (characterp key)
         (set-transient-map
          (let ((map (make-sparse-keymap)))
-- 
2.35.1