Re: 26.1: calc-mode header line [PATCH]

[Lars Ingebrigtsen]

Boruch Baum <boruch_baum@gmx.com> writes:

> +The *Calc* and *Calc Trail* buffers now use 'header-line-format' to
> +present a persistent buffer header line, and they are sized based upon
> +the window width upon launch. The header-line for the *Calc Trail*
> +buffer is no longer part of the buffer's text and no longer scrolls
> +off the visible display, unless on sets 'calc-show-banner' to NIL.

The patch doesn't apply to Emacs 28, so I've respun it (included below).

The result looks nice, but one comment:

+    (setq header-line-format
+          (let* ((fract  (/ (* (window-width) 2) 3))
+                 (factor (if (> fract 22) 21 10))
+                 (size   (/ (- fract factor) 2))
+                 (fill (make-string size ?-))
+                 (pre  (replace-regexp-in-string ".$" " " fill))
+                 (post (replace-regexp-in-string "^." " " fill)))
+            (concat pre
+                    (if (= factor 21) "Emacs Calculator Mode" "Emacs Calc")
+                    post))))

This is somewhat inscrutable, and is repeated twice (once for the calc
buffer and once for the trail buffer).

It just centres whatever the string like "--- this ---", so it seems
like it should land in a single function for reuse.

diff --git a/lisp/calc/calc.el b/lisp/calc/calc.el
index fb1287baaa..2688ca14a4 100644
--- a/lisp/calc/calc.el
+++ b/lisp/calc/calc.el
@@ -1396,15 +1396,37 @@ calc-trail-mode
   (setq buffer-read-only t)
   (make-local-variable 'overlay-arrow-position)
   (make-local-variable 'overlay-arrow-string)
-  (when (= (buffer-size) 0)
-    (let ((inhibit-read-only t))
-      (insert (propertize "Emacs Calculator Trail\n" 'face 'italic)))))
+  (if (and (not calc-show-banner)
+           (= (buffer-size) 0))
+      (let ((inhibit-read-only t))
+        (insert (propertize "Emacs Calculator Trail\n" 'face 'italic)))
+    (setq header-line-format
+          (let* ((fract  (/ (window-width) 3))
+                 (factor (if (> fract 19) 22 10))
+                 (size   (/ (- fract factor) 2))
+                 (fill (make-string size ?-))
+                 (pre  (replace-regexp-in-string ".$" " " fill))
+                 (post (replace-regexp-in-string "^." " " fill)))
+            (concat pre
+                    (if (= factor 22) "Emacs Calculator Trail" "Calc Trail")
+                    post)))))
 
 (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
+    (setq header-line-format
+          (let* ((fract  (/ (* (window-width) 2) 3))
+                 (factor (if (> fract 22) 21 10))
+                 (size   (/ (- fract factor) 2))
+                 (fill (make-string size ?-))
+                 (pre  (replace-regexp-in-string ".$" " " fill))
+                 (post (replace-regexp-in-string "^." " " fill)))
+            (concat pre
+                    (if (= factor 21) "Emacs Calculator Mode" "Emacs Calc")
+                    post))))
   (setq max-lisp-eval-depth (max max-lisp-eval-depth 1000))
   (when calc-always-load-extensions
     (require 'calc-ext))
@@ -1451,7 +1473,6 @@ calc
                 (pop-to-buffer (current-buffer)))))))
       (with-current-buffer (calc-trail-buffer)
         (and calc-display-trail
-             (= (window-width) (frame-width))
              (calc-trail-display 1 t)))
       (message "Welcome to the GNU Emacs Calculator!  Press `?' or `h' for 
help, `q' to quit")
       (run-hooks 'calc-start-hook)
@@ -1986,13 +2007,8 @@ calc-refresh
              (calc-any-evaltos nil))
         (setq calc-any-selections nil)
         (erase-buffer)
-        (when calc-show-banner
-          (insert (propertize "--- Emacs Calculator Mode ---\n"
-                              'face 'italic)))
         (while thing
           (goto-char (point-min))
-          (when calc-show-banner
-            (forward-line 1))
           (insert (math-format-stack-value (car thing)) "\n")
           (setq thing (cdr thing)))
         (calc-renumber-stack)
@@ -2076,7 +2092,6 @@ calc-trail-buffer
           (eq (marker-buffer calc-trail-pointer) calc-trail-buffer))
       (with-current-buffer calc-trail-buffer
        (goto-char (point-min))
-       (forward-line 1)
        (setq calc-trail-pointer (point-marker))))
   calc-trail-buffer)
 
@@ -2144,10 +2159,8 @@ calc-trail-here
   (if (derived-mode-p 'calc-trail-mode)
       (progn
        (beginning-of-line)
-       (if (bobp)
-           (forward-line 1)
          (if (eobp)
-             (forward-line -1)))
+          (forward-line -1))
        (if (or (bobp) (eobp))
            (setq overlay-arrow-position nil)   ; trail is empty
          (set-marker calc-trail-pointer (point) (current-buffer))
@@ -2161,7 +2174,7 @@ calc-trail-here
            (if win
                (save-excursion
                  (forward-line (/ (window-height win) 2))
-                 (forward-line (- 1 (window-height win)))
+                 (forward-line (- 2 (window-height win)))
                  (set-window-start win (point))
                  (set-window-point win (+ calc-trail-pointer 4))
                  (set-buffer calc-main-buffer)


-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no