Subject: bug#43295: 26.1: calc-mode header line [UPDATED PATCH]

From: Boruch Baum <[email-masked]>
Date: Sat, 12 Sep 2020 20:43:24 -0400

On 2020-09-11 14:15, Lars Ingebrigtsen wrote:
> Could you send a new patch that has all the changes that you want that I
> can just apply?  Adding discussion into the patch itself isn't very
> helpful.  :-)

In the attached patch:

1) the hunk @1421 restores the behavior that Eli wants

2) the hunk @2010 corrects the width calculation in that case

3) the hunk @2133 better handles the header line for the trail display
--
hkp://keys.gnupg.net
CA45 09B5 5351 7C11 A9D1  7286 0036 9E45 1595 8BC0
--- /home/optimum/calc.el	2020-09-11 15:58:55.263774535 -0400
+++ ./calc.el	2020-09-11 13:21:07.485259155 -0400
@@ -1396,8 +1396,6 @@
         (let* ((len-long (length long))
                (len-short (length short))
                (fudge (or fudge 0))
-               ;; fudge for trail is: -3 (added to len-long)
-               ;; (width  ) for trail
                (factor (if (> width (+ len-long fudge)) len-long len-short))
                (size   (/ (- width factor) 2))
                (fill (make-string size ?-))
@@ -1421,13 +1419,22 @@
   (make-local-variable 'overlay-arrow-string)
   (when calc-show-banner
     (calc--header-line "Emacs Calculator Trail" "Calc Trail"
-                       (/ (window-width) 3) -3)))
+                       (/ (window-width) 3) -3))
+  (when (zerop (buffer-size))
+    (let ((buffer-read-only nil))
+      (insert (propertize "Emacs Calculator Trail\n" 'face 'italic)))))

 (defun calc-create-buffer ()
   "Create and initialize a buffer for the Calculator."
   (set-buffer (get-buffer-create "*Calculator*"))
   (or (derived-mode-p 'calc-mode)
       (calc-mode))
+  (when calc-show-banner
+    (calc--header-line "Emacs Calculator Mode" "Emacs Calc"
+                       (if calc-display-trail
+                         (/ (* (window-width) 2) 3)
+                        (window-width))
+                       1))
   (setq max-lisp-eval-depth (max max-lisp-eval-depth 1000))
   (when calc-always-load-extensions
     (require 'calc-ext))
@@ -2010,7 +2017,7 @@
 	 (erase-buffer)
          (when calc-show-banner
            (calc--header-line  "Emacs Calculator Mode" "Emacs Calc"
-                       (* 2 (/ (window-width) 3)) -3))
+                             (window-width) 1))
 	 (while thing
 	   (goto-char (point-min))
 	   (insert (math-format-stack-value (car thing)) "\n")
@@ -2133,29 +2140,32 @@
 (defun calc-trail-display (flag &optional no-refresh interactive)
   (interactive "P\ni\np")
   (let ((win (get-buffer-window (calc-trail-buffer))))
-    (if (setq calc-display-trail
+    (cond
+     ((setq calc-display-trail
 	      (not (if flag (memq flag '(nil 0)) win)))
-	(if (null win)
-	    (progn
+	(when (null win)
               (if calc-trail-window-hook
                   (run-hooks 'calc-trail-window-hook)
-                (let ((w (split-window nil (/ (* (window-width) 2) 3) t)))
-                  (set-window-buffer w calc-trail-buffer)))
+            (setq win (split-window nil (/ (* (window-width) 2) 3) t))
+            (set-window-buffer win calc-trail-buffer))
               (calc-wrapper
                (setq overlay-arrow-string calc-trail-overlay
                      overlay-arrow-position calc-trail-pointer)
                (or no-refresh
                    (if interactive
                        (calc-do-refresh)
-                     (calc-refresh))))))
-      (if win
-	  (progn
+                 (calc-refresh)))))
+        (with-current-buffer calc-trail-buffer
+          (when calc-show-banner
+              (calc--header-line "Emacs Calculator Trail" "Calc Trail"
+                                  (window-width win) -3))))
+     (win ; not calc-display-trail
 	    (delete-window win)
 	    (calc-wrapper
 	     (or no-refresh
 		 (if interactive
 		     (calc-do-refresh)
-		   (calc-refresh))))))))
+              (calc-refresh)))))))
   calc-trail-buffer)

 (defun calc-trail-here ()