From: Po Lu <luangruo@yahoo.com>
Date: Fri, 10 Dec 2021 03:30:07 +0000 (+0800)
Subject: Fix bob detection when pixel scrolling upwards
X-Git-Tag: emacs-29.0.90~3606^2~3
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=59db96d83ae837b3a3d82a979cd97a271bcd86bf;p=emacs.git

Fix bob detection when pixel scrolling upwards

* lisp/pixel-scroll.el (pixel-point-and-height-at-unseen-line):
Don't go to the beginning-of-visual-line if bobp.
---

diff --git a/lisp/pixel-scroll.el b/lisp/pixel-scroll.el
index 432a5dc52cf..29d8e7e0255 100644
--- a/lisp/pixel-scroll.el
+++ b/lisp/pixel-scroll.el
@@ -399,7 +399,8 @@ character on the unseen line just above the scope of current
 window, and the pixel height of that line."
   (let* ((pos0 (save-excursion
                  (goto-char (window-start))
-                 (beginning-of-visual-line)
+                 (unless (bobp)
+                   (beginning-of-visual-line))
                  (point)))
          (vscroll0 (window-vscroll nil t))
          (line-height nil)