Fix picture-mode wrt double-width characters

* lisp/textmodes/picture.el (picture-insert): Check the width of
the character being replaced, not just that of the replacement.
(Bug#1808)

Copyright-paperwork-exempt: yes

1 files changed, 5 insertions, 1 deletions

diff --git a/lisp/textmodes/picture.el b/lisp/textmodes/picture.el
index 4aee2734158..b77f8e9717c 100644
--- a/lisp/textmodes/picture.el
+++ b/lisp/textmodes/picture.el
@@ -272,7 +272,11 @@ Use \"\\[command-apropos] picture-movement\" to see commands which control motio
         (or (eolp)
             (let ((pos (point)))
               (move-to-column col t)
-              (delete-region pos (point)))))
+              (let ((old-width (string-width (buffer-substring pos (point)))))
+                (delete-region pos (point))
+                (when (> old-width width)
+                  (insert-char ?  (- old-width width))
+                  (goto-char pos))))))
       (insert ch)
       (forward-char -1)
       (picture-move))))